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General => General Forum => Topic started by: hnash53 on January 17, 2007, 07:15:25 PM

Title: battery bank charging
Post by: hnash53 on January 17, 2007, 07:15:25 PM
I have purchased sixteen 12-volt deep cycle batteries, each with 134 amp-hours @ 20 hr rate.  I plan to wire two sets of 8 batteries each in parallel to increase my amp-hour capacity, and then to wire these sets together in series to increase the voltage to 24 volts.

My question:  Can I still charge this bank of batteries with my 12-volt windturbine, my 12-volt solar panels, and my 12-volt battery charger?

Many thanks for your comments.

Hal Nash
Wyoming
Title: Re: battery bank charging
Post by: MountainDon on January 18, 2007, 12:02:09 AM
QuoteI plan to wire two sets of 8 batteries each in parallel to increase my amp-hour capacity, and then to wire these sets together in series to increase the voltage to 24 volts.  Can I still charge this bank of batteries with my 12-volt windturbine, my 12-volt solar panels, and my 12-volt battery charger?
 

The simple answer is, NO.  :( A more complete answer will follow.
Title: Re: battery bank charging
Post by: MountainDon on January 18, 2007, 12:46:43 AM
Quote
QuoteI plan to wire two sets of 8 batteries each in parallel to increase my amp-hour capacity, and then to wire these sets together in series to increase the voltage to 24 volts.  Can I still charge this bank of batteries with my 12-volt windturbine, my 12-volt solar panels, and my 12-volt battery charger?
 

The simple answer is, NO.  :( A more complete answer will follow.

First it doesn't matter one iota where the charging power is coming from as far as the battery/batteries is/are concerned. In charging a nominal 12 VDC battery the voltage during different charging phases can run as high as 15 volts, typically from 13.6 to 14.2 or so. So a 24 VDC battery system would require from about 27.2 volts up to 30 volts. So trying to charge a 24 VDC system with 12 volts will not work.

However, your 12 VDC (nominal) solar panels can be connected in series instead of parallel to provide higher voltages (2 = 24, 3 = 36, etc.) You didn't state how your panels are wired, but I assume they are in parallel because you called them 12 volt. However (there's always a catch), if you run them in series or series and parallel to provide the 24 VDC output you may need a new charge controller. Some controllers are adjustable or prongramable. Some are not.

Using the battery charger faces the same problem, good for charging a 12 volt battery but not 24 volts.  :(

As for the wind turbine I'm not very familiar wind wind generators, I do know their regulation system differs from that used in solar systems. However, unless the manufacturer has allowed for converting the output from 12 to 24 volts by rewiring something in the unit, you face the same problems as above.

Not to belabor the problems you face, there's another point, which may be moot since you already have the sixteen 12 volt batteries. Some alternative energy "experts" are of the opinion that layering more than three parallel sets of battery strings is not advisable. Some don't even advise going or two layers, and others don't seem to have an opinion. I think those guys (without a strong opinion) just want to sell batteries and don't really care what happenes a few years down the road.  :o

For what it's worth, and this is just my opinion, formed after using a multitude of batteries, different types, voltages, etc. over more than  30 years in RV applications, I would not go over two parallel layers. Just my opinion.

Here's a link explaining the potential problem...    http://www.thesolar.biz/Keeping_batteries_alive.htm

I have experienced the "lazy string" problem in large RV battery banks. (my RV's have always had more batteries than most as I tend to like to really get away from it all in a big way, for days at a time, and are loath to run my genset, yet I love my conveniences, microwave, furnace, etc. Kinda schizo, but that's me. See there I go off topic again....   ::))

To those recommendations on that link, I would add another thing or two to do to help achieve maximum battery life.
1. use highest quality cabling using mechanically crimped connectors. A properly made mechancial (crimped by machine or proper crimping tool) is superior to a soldered connection because (A.) solder has higher resistance than copper wire and (B.) high temperatures required to solder large cables invariably burns the insulation on the cables. Use the largest diameter cable, like 4/0

2. Instead of connecting the parallel strings with more 4/0 cable connect each parallel string to a solid copper bus bar of sufficient ampacity. A good copper bus bar will have way lower resistance than the series connecting string of cables. This will help eliminate that potential problem area. A good source for copper connecting products is Storm Copper    http://www.stormcopper.com/    They have all sorts of copper connection products and the bus bar material can be obtained blank for a drill it yourself approach to save a little money.

Title: Re: battery bank charging
Post by: glenn-k on January 18, 2007, 03:49:41 AM
I don't know how much power you are going for, Hal, but there are some decent 12 volt to 110 inverters out there.  You could just run it all 12 volt using the buss like Mountain Don mentioned.

It requires heavy cable on the low voltage side as Mountain Don mentioned.

There may be some step up regulators now too.  

Low voltage is not very efficient so cable sizes get large and expensive.

You can charge the groups of 12v separate, but its a real hassle keeping things even close to balanced and batteries will give you a lot of trouble.  I played that game when I first started.
Title: Re: battery bank charging
Post by: hnash53 on January 18, 2007, 10:55:33 AM
Glenn and MountainDon,

Thanks for your input.  I'm new to this game, and it seems that everyone has their own rules of the game that they play by.  I've gotten different answers from different sources.

Maybe it would be easier to string all 16 batteries in parallel @ 12volts and a shit-load of amp-hours.  Then all my charging sources would be fine...solar, wind, dc generator.

Glenn, you said you started out with batteries but sounds like it became a headache.  What are you getting at?  In a totally offgrid location, what other solutions are there?

Thanks, guys...appreciate the info.  Don...schizo is OK.  Everyone is schizo...just some of us are honest enough to admit it!!
Title: Re: battery bank charging
Post by: glenn-k on January 18, 2007, 12:14:21 PM
I didn't make that real clear did I.  I started out with a group of mixed batteries - car batteries -deep cycle- some charged too much - some not enough -  I'd try to charge the low ones by them selves to even them out with the rest, but some of them may have had other problems anyway.  I was constantly fooling with them.

I finally went to 12 L16's - 6v 375 ah and series'd 4 then paralleled the 3 groups for my 24v system.

I think you are right in your case - you have the stuff for a 12 v system - use it.  I have no question that the bus bar Mountain Don is talking about is the best way to go.  I'm not doing that but have always thought it would be easier than the cables and jumpers and stuff I'm using.

You will find that terminal ends are expensive if making your own cables.  I buy heavy entrance cable then smash copper tubing of the appropriate size over it then drill a hole through it to bolt it.  

You could get the buss bars then run all the batteries to the buss bars as probably the best way of doing it.  Paralleling 2,4,8 etc. then paralleling them on the bus has a bit more risk of losing a battery here and there through connections and if they all go to the bus it is easier to work on a problem one than to pull one out of a group to clean terminals etc.  Smaller cables can be used to the buss - if you stack a bunch then cables have to vary or use oversize throughout - things get more complicated.  24v systems can use smaller cables than 12 but you need to work with what you have.  I also started out 12v but switched to 24v when I got my 24v wind generator.

All in all, they still require checking every so often for problems.
Title: Re: battery bank charging
Post by: MountainDon on January 18, 2007, 04:07:58 PM
Quote

You will find that terminal ends are expensive if making your own cables.  I buy heavy entrance cable then smash copper tubing of the appropriate size over it then drill a hole through it to bolt it.  
I must admit to having a couple connector ends like those Glenn. I went the slightly more elegant route and squished the bejeebers outa the copper tubing with a 20 ton hydraulic press.   :o   They might not meet NEC code, whaddaya think?   :-/  Not too worried about that myself, but it's something one should keep in mind if one is trying to jump thru all the hoops.  :P

Here's a link of interest for some of the more reasonably priced UL listed connectors I've found.    http://www.solarseller.com/quick_cable_copper_cable_lugs.htm    that's direct to their copper lug connector page. Lots of other interesting stuff as well.

I also use a red spray coating on the connections, it seals the connections so they don't corrode as easily. Marketed with the Exide name on the can I have. Smells like lacquer.
Title: Re: battery bank charging
Post by: glenn-k on January 18, 2007, 04:23:27 PM
In the sprays, they have a cleaner also but baking soda and water does quite well on most of it.  I use the Red spray too when I've done an especially nice job and want to reward myself by making it look pretty. :)

I usually smash the copper tubing with a hammer - I squish it together pretty tightly.  For special effects I sometimes use the ball peen end. :)
Title: Re: battery bank charging
Post by: MountainDon on January 18, 2007, 09:44:17 PM
QuoteI don't know how much power you are going for, Hal, but there are some decent 12 volt to 110 inverters out there.

There are many good brands, one that I like (I have one of their units in the RV) is Exeltech     www.exeltech.com    Their MX series is expandable in 1000 watt increments up to darn near anything. That is as long as your battery cables are up to the power demands. Not cheap but then none of the good pure sine wave units are. Unless they're Chinese and in my view a lot of them are suspect.  

One source for them is   http://www.nwpwr.com/products/inverters/mx_series.htm
Title: line losses through long cables from wind turbines
Post by: hnash53 on January 19, 2007, 07:43:56 PM
[size=14]You guys seem to know a bit about all this Alt Energy stuff.

How about this:  What kinds of energy losses occur if my wind turbine is about 80 yards from my batteries?

Give me some good news, eh?

Thanks.

Hal[/size]
Title: Re: line losses through long cables from wind turb
Post by: MountainDon on January 19, 2007, 08:19:09 PM
Ok. You can sort this all out yourself; go here  
http://www.countryplans.com/cgi-bin/yabb2/YaBB.pl?num=1168907350

There you will find several different links to voltage drop calculators. All except the last one are web based utilities. They vary a little in how they are used but basically you fill in the blanks and it gives an answer.  The variables involved include:
1.  system voltage
2.  maximum amperage through the conductor
3.  length of cable (some use a one way distance (ie from turbine to where the controller / batteries are), and some use the two way distance (ie 80 yards from turbine to batteries = two way distance of 160 yards))
4. size or gauge of cable (AWG = american wire gauge)
5. voltage drop or loss expressed as a percentage or as a finite number.
6. some of the calculators also allow for a choice between copper or aluminum cable. copper is best for havimg lower resistance, aluminum may be cheaper even if you have to use a larger size cable. Check the $$. Also I believe if you bury the cable you must use copper... even if in a conduit in the ground, conduit is considered wet and moisture results in a corrosion problem with aluminum)

You would want to keep the voltage drop to a maximum of 2% if at all possible; 3% is not too bad. Just a sec...  :-/that's correct when we're talking about power from solar (photovoltaic) panels. They are not too efficient to begin with so we want to keep as much power as possible. For a wind turbine system in a well producing area I imagine you could go to 5% or so loss. Like I said, I'm not well versed in the wind power area. ....if I could harness my farts, tha'd be a really powerful energy source....   ::)

I'm not sure how well versed you are in electrical "nuts and bolts", so I'll mention a few things. There is resistance to current flow in any wire/cable. The thicker the cable the less resistance. If you raise the voltage for a given number of watts the amps decrease... 12 VDC at 10 amps = 120 watts    AND  24 VDC at 5 amps = 120 watts (amp-hours) So for a given length of cable you would need a larger cable size to push the 120 watts at 12 VDC as compared to 24 VDC. Wire/cable size is measured in AWG, and the [highlight]smaller the number, the larger the cable[/highlight]. When you get down to 1 AWG the numbering changes and you go to  1/0 awg, then 2/0, 3/0, 4/0 etc.

So if your turbine is 80 yards from the batteries, that's 80x3 = 240 feet. You have 12 VDC. What is the max amperage output of the turbine? Let's use 10 amps as an example. What's the size of your cable? Let's use #4 AWG for an example.

Using the calculator at   http://www.nooutage.com/vdrop.htm    let's see the results...   Uh-oh that comes out with a 12.4% drop. Too much wasted energy.  If we go up one wire gauge size to #2 AWG.... then it's a drop of 8%, still high.  You can play around with different wire gauges, amps, volts and distances to see how it all relates.   This voltage drop thing is one reason I previously mentioned wiring the solar panels in series  play with the calculators and if you have further questions, I'll try to answer them.

I hope I helped lift the fog a little. G/L



Title: Re: battery bank charging
Post by: glenn-k on January 19, 2007, 08:31:05 PM
What he said.

Low voltage  losses are heavy in small cable.  

Do you know the model of your wind generator or maximum output?  We could tell you more from there if we know that.

As Mountain Don said, if you lose it all in your cable, it does nothing to charge your battery.  It helps to think of it like water.  A short small hose will put out quite a bit of water, but as it gets longer and longer you come to a point where water will no longer flow.  Your batteries are your bucket.  If the hose is long it must be large to still carry the same amount of water as the small short one and be able to fill the bucket.
Title: Re: battery bank charging
Post by: MountainDon on January 19, 2007, 08:38:06 PM
QuoteDo you know the model of your wind generator or maximum output?  We could tell you more from there if we know that.
I'd be happy to run the numbers for you.  ;D I assume the wind turbine is already in place and you have used it with a smaller, older battery?? If so do you know the cable size you have as well?

And ya'll can call me Don, instead of the longer MountainDon.... I don't own much of that mountain anyways   :(
Title: Wind generator specs
Post by: hnash53 on January 20, 2007, 03:18:31 PM
I am building a "home brewed" wind generator as shown at the following link:

http://www.lookout2000.com/windpower/

It is using a 12V car alternator with pulley system to generate 60amps for a total (theoretical) of 720 watts.

This is the unit I am describing in all of my questions to you.

I'll check out the links to try and understand line losses.

Thanks, Don and Glenn.
Title: Re: Wind generator specs
Post by: MountainDon on January 20, 2007, 04:08:01 PM
QuoteI am building a "home brewed"
Hal, I am a big fan of home brewed stuff myself. I have 4 gallons that'll be ready in a few days....  ;D Ooops, that's the other forum    :-[   I'll post some numbers for you later today some time  
Title: Re: battery bank charging
Post by: benevolance on January 20, 2007, 05:32:24 PM
I just wonder why not try to utilize the high amp altenators that are 90 amps instead of merely 60....

I junked out a firetruck one time and it had a 200 amp altenator on it....Wouldn't this be a better base to build the wind generator on?
Title: Re: battery bank charging
Post by: MountainDon on January 20, 2007, 05:48:35 PM
Okay here goes my 2 cents worth.  The CHART below has amps and watts at 12 VDC in the left hand column, wire size (AWG) across the top. The values inside the chart represent the calculated voltage drop in percent. The chart is assuming a transmission distance of 240 feet one way direction.

I've included the AWG 10 column only for comparison purposes, that is the largest size wire you normally would find in the house wiring AC circuits, like for a range or dryer, NOT an incoming supply line.  All your other house AC circuits would be either 12 or 14 gauge, even smaller size wire.

How often the generator will get up into the upper ranges is something I don't know. But you can see that even with the 4/0 cable, that's about the largest cable you'll find, the losses get kind of high. That percentage number is how much of the produced energy is going to waste heating your cables. Sizing the cable down around to #4 or #2 cables sizes has a tremendous amount of  power going to waste. Those larger cables, 2/0 and 4/0 get to be rather pricey when you're looking at two 240 foot lengths, one positive and one negative. I had a quick look at a local supplier of battery cable in bulk; 500 feet of 4/0 is $2873.00 and 500 feet of 2/0 is $1053

More to come.....




Title: Re: battery bank charging
Post by: MountainDon on January 20, 2007, 06:06:39 PM
More...

Note that was for battery cable and does not meet NEC code. I couldn't check for NEC approved 4/0 and 2/0 cable but they're probably more money.

ALL may NOT be lost though. [highlight] ANOTHER IDEA:[/highlight] If you are going to attempt to build a wind generator yourself using that one in the link as a guide why not subsitute a 24 VDC alternator from some vehicle or machine with a 24 VDC electrical system? I have an old Toyota Land Cruiser (Canadian issue) diesel with a 24 VDC electrical system, including alternator and stater. Yes, that would be more expensive than the GM style alternator shown in those plans.  The GM are as common as mouse turds and cheaper as a result. At 24 VDC you would have one-half the amps for the same watts. [12 VDC @ 40 amps = 480 watts. At 24 VDC the 480 watts is achieved with a current of only 20 amps] That will cut the required conductor size down by about 2 wire sizes. Run one of those calculators to see. Here's one example tho'...
12 VDC suppling 480 watts for 240 feet over 4/0 cable gives a 12.8% drop in voltage, but changing to 24 VDC equals a drop of only 6.4%.... double the voltage = half the voltage drop.... OR with 24 VDC, 480 watts, 240 feet and smaller (cheaper) 1/0 cable a drop of 10.4%.   That's a little less drop for much cheaper cable.

On the downside, using 24 VDC for the wind gen and the batteries gets you back to the incompatibility between your other 12 VDC charging systems, solar and generator.  

Title: Re: battery bank charging
Post by: MountainDon on January 20, 2007, 06:19:29 PM
[highlight]YET ANOTHER IDEA![/highlight]  If the batteries were located right there at the wind generator your cabling needs for a 12 VDC system would be minimized. What you would have to do though is install your dc to ac (pure sine wave) Inverter(s) up there as well. Then you'd run 120 VAC (240VAC?) to the cabin. The higher voltage power would require less in cable size and cable cost. Of course as with nearly every upside change there's a downside. The 120 VAC power cables are more dangerous if in the air overhead and they fall.

An off topic aside, but a safety thing..... 12 Volts is generally not as dangerous as 120 Volts as fas as electrocution goes. You still have to be careful with 12 and 24 VDC battery systems but you are less likely to be elctrocuted. The danger point is reached at about 48 VDC. Oh, but of course a mistake can blow up a battery and that is an experience we can all do without.

Back to topic... Another downside to the remote batteries is that batteries don't like the cold anymore than I do. If they were up on that windy ridge and the cabin is NOT, I guess the batteries would be sitting there in an unheated box assuming whatever the ambient air temp is. You can easliy loose half you rated battery capacity from cold.  They don't like too much heat either. Batteries like the same temperature range as people.

I've worn out my two fingers, that's all for now   :)
Title: Re: battery bank charging
Post by: MountainDon on January 20, 2007, 06:24:33 PM
QuoteI just wonder why not try to utilize the high amp altenators that are 90 amps instead of merely 60....

I junked out a firetruck one time and it had a 200 amp altenator on it....Wouldn't this be a better base to build the wind generator on?

IF the gen and batteries were closer together, that could be advatageous.

My Jeep and RV have 175 amp and 160 amp alternator/welders respectively supplying the juice, but that's another topic.
http://www.premierpowerwelder.com/specs/ppwspecs.html
Their showers are pretty nifty too
http://www.premierpowerwelder.com/underhood/underhood.html
Title: Re: battery bank charging
Post by: hnash53 on January 20, 2007, 07:40:39 PM
Below is a quote from http://www.hydrogenappliances.com/powerpmas.html  :

[size=12]"...standard automotive alternators are usually putting out 40 to 50 volts into the 12 volt battery in your car. That's right! It won't harm the battery AS long as the battery is not FULL. It can take high levels of charging voltage no problem. A lead acid battery will easily buffer high input voltages.  It is normal to charge batteries with much more power than their output ratings. Only start worrying when the battery is fully charged and THEN any additional power must stop coming into it or must be dumped to keep the battery cool and from producing explosive hydrogen gas.
 
To make a long story short a 12 volt battery that is being charged with a wind turbine putting out 50 volts will still only read "12 volts" to a volt meter proving that the high voltage power is easily being swallowed up by the big lead plates of your battery." [/size]

[size=14][/size]So according to this, if I have an alternator that does not have a regulator on it (i.e. an externally regulated one but without an external regulator attached) I can put out more voltage than 12 volts and therefore I could experience some line loss but still have enough valuble wattage arriving at my battery bank.  

I could regulate my battery bank with a device seen here:  http://www.hydrogenappliances.com/batteryregulator.html

It dumps any excess charging that arrives at my battery bank to some kind of heat sink, such as a 12 volt water heater inside the cabin.

Benevolence, your comment sort of goes along with what I am proposing above.  Your thoughts welcome.

Thanks, all.
 
A battery is basically a BIG capacitor in electronic terms. Once your batteries are fully charged you must THEN stop putting any additional power into it!
Title: Re: battery bank charging
Post by: MountainDon on January 20, 2007, 08:01:16 PM
QuoteI could regulate my battery bank with a device seen here:  http://www.hydrogenappliances.com/batteryregulator.html
It dumps any excess charging that arrives at my battery bank to some kind of heat sink, such as a 12 volt water heater inside the cabin.

Right. Wind and hyro power systems use that sort of diversion device for the power not needed to charge the batteries. Cab be used to heat water or air.
Title: Re: battery bank charging
Post by: MountainDon on January 20, 2007, 08:01:39 PM
Quoteif I have an alternator that does not have a regulator on it (i.e. an externally regulated one but without an external regulator attached) I can put out more voltage than 12 volts and therefore I could experience some line loss but still have enough valuble wattage arriving at my battery bank.  
No argument there, but I believe that if you move the regulator down to where the batteries are there are then 4 wires involved between the alt and the reg. Not sure if they all have to be whatever max size is indicated by the max current flow.  :-?
Title: Re: battery bank charging
Post by: Amanda_931 on January 20, 2007, 09:23:36 PM
I gather that the first rule of off grid with batteries is:

[size=16]Everybody screws up their first set of batteries.[/size]

(I only have one in the trailer, and supposed to have an inverter.  But if the I leave it on all the time it will overcharge the battery--might have worked better with two--but that first--"deep cycle boat type" really didn't last very long--and I'm not all the way off grid--part of the problem, actually)

Now, with the inverter broken, I hook up a battery charger every couple of days,, or when my meter says I'm at the 75% level.

Don't know if I've really learned my lesson yet, though.

I've had a little experience driving (and charging) electric forklifts though.
Title: Re: battery bank charging
Post by: MountainDon on January 20, 2007, 09:44:17 PM
Amanda, if that trailer is a standard RV type of trailer and you are using the equipment that came with it, then that is the problem. Most RV's, except for newer and upscale models come with a combination charger / converter that is supposed to keep the battery full from the "shore" power AC you plug in to. Those invariably don't put out enough power to charge a really low battery, nor do they shut off so as to not overcook the battery. More than one battery might slow doen the overcharging, but in the end toasted batteries are the result. I killed a couple batteries when I got my first RV. I now use a separate charger from Iota. It does throttle right down to just enough to keep the batteries at full but not overcooked.

The 75% figure you mentioned... do you mean you recharge when the battery is still 75% full, or that it's 75% empty.  If you aren't letting the battery go below 75% of a full charge that's Great. If you're going down to 75% discharged that's not nearly so good. A 50-50 deal; 50% deal is much better with respect to battery longevity. But I know from experience it's difficult at times to keep the charge above 50% without it seeming like you are always putting the battery on and off charge. That's why I went to four six volt batteries when I toasted my second battery within the first two years. That was a long time ago. Batteries have been better to me since then because I was better to them.

I've never driven a fork lift before, but would think you need one to move one of those giant batteries around. From what I've heard in an AE situation they can easily be completely function after a quarter century of use.


Best thing for any battery, deep cycle or not, is to never go below 50%. And the shallower your discharge the longer the life. Going down to
Title: Re: battery bank charging
Post by: Amanda_931 on January 20, 2007, 10:28:03 PM
25% down, 75% full.

Electric forklifts have very little in the way of weight penalty.  Probably nothing.  When compared to the propane or whatever powered ones.

Consider the amount of weight needed to put up to two tons 18 feet in the air--and a couple of feet in front of your front wheels.  I never turned one over, but I have come close a time or two, generally when trying that and getting in a hurry.

I'm thinking  a chain hoist plus a ladder into my lofts.  Probably in the battery house too.  But I gues I'd get the less expensive golf cart batteries first--just in case I haven't learned my lessons.
Title: Re: battery bank charging
Post by: MountainDon on January 20, 2007, 10:42:39 PM
Quote25% down, 75% full.
That's the way to treat them.

I think golf cart batteries are a good place to begin. Mistakes don't cost so much. The other good thing is that once a set of batteries get about a year old you should not try increasing their numbers; adding another parallel string. That's because the batteries will soon act only as good as the poorest, generally oldest battery. I made that mistake early on as well when I tried going from one deep cycle RV battery to two in parallel.

My first set of four golf cart batteries (a series/parallel setup for 12 VDC) lasted three years in the RV before I noticed any significant decrease in capacity. I also wanted more power reserve. Bought six new ones and they went four years. I saw some at Sam's Club the other day for $64 each.
Title: Re: battery bank charging
Post by: glenn-k on January 20, 2007, 11:02:15 PM
I use a decent sized welder for a backup generator part of the time.  It has an 8000 watt generator but is a DC welder also.  When I was working in the diesel shop in '70 an old friend here showed me how to jump start trucks etc. with a welder.

A DC welder - I set it electrode positive, is one heck of a battery charger -- yes -- you can toast your batteries if you don't watch it, but it sure takes care of a lot of the bulk charging quickly - so I plug in the inverter charger and let it do its thing the hook up the welding leads and watch the voltmeter.  I make all connections away from the battery as there is bound to be some hydrogen around them.  Proper polarity must be observed and it needs t be set for constant current as in stick welding - then the voltage will pull down to battery level if not turned too high.  Don't put it on constant voltage as in wire welding - that doesn't work well and will fry them quickly.  I use an extra cable and connect several feet away.  It will soon mess up light duty batteries but the larger batteries such as L16's in a big bank can take quite a bit.  Note that this is for people who are not afraid of sparks and who will remember remember to keep them away from the batteries.  When was your last acid and plastic shrapnel bath? :-?

My batteries thank all of you.  All this talk about batteries made me go out and pay attention to them.  I used about 4 gallons of distilled or rainwater to top them all off.  They were still at the safe level but 12 L16's can get pretty thirsty even if not excessively low.   :)  Note that older batteries will want water more often than new ones.

Note that I have blown up a few batteries in my day. :-/
Title: Re: battery bank charging
Post by: desdawg on January 21, 2007, 01:15:54 AM
(http://img284.imageshack.us/img284/1646/nuclearexplosionbl4.gif)
(http://img175.imageshack.us/img175/3135/guywithpipecs5.gif)
Title: Re: battery bank charging
Post by: glenn-k on January 21, 2007, 01:31:26 AM
You ought to try it some time desdawg - lots of fun -- and works if you do it right.
Title: Re: battery bank charging
Post by: desdawg on January 21, 2007, 01:36:56 AM
My batteries suffer since I am not there enough to properly maintain them. I think Amanda is right. It takes one full set to realize the importance and get the right mindset.
Title: Re: battery bank charging
Post by: glenn-k on January 21, 2007, 01:41:40 AM
Solar panels on a charge regulator should keep them happy while you are away- they like to be well charged but not overcharged all the time.  Low charge batteries freeze easier I read - I guess because gravity is lower.  Worse than that is that they sulfate easily and may never take a good charge again without a long time on a rejuvenator to break up the sulfate crystals.
Title: Re: battery bank charging
Post by: MountainDon on January 21, 2007, 02:29:17 AM
Hey Desdawg, Glenn's right. If you are going to leave the batteries to look after themselves, you [1] give them an equalization charge (makes feel good) and [2] that leaves them in a fully charged state and [3] make sure they are fully watered (always water after they're fully charged) , they'll be fine. The solar panels and regulators have tremendously good MTBF rates, there's generally no problem. Fate could always raise it's igly fickle finger, but then that's life and you just have to roll with it.  :)  

A fully charged lead-acid battery won't freeze until about -90 degrees F. I hope it doesn't get that cold where you are.  When in veeeeery cold temperatures the effective capacity of the battery falls drastically. (When I still lived in Canada and had a gas station I used to love winter.... loved it for the distress calls... "my battery's dead, please come jump start me" ...$$$)  
...
Sulphation results when the batteries are left in a discharged state for a while. It's always bad news, though some treatments can help ressurect the dead. I think the desulphators do work but the battery is never like new. (personal bad experience  :'(  )  
Title: Re: battery bank charging
Post by: desdawg on January 21, 2007, 08:23:58 AM
The solar panels and charge controller keep them up and I have them ventilated so that isn't a problem. They get low on water and after 4 months of winter. And I have to try to remember distilled water. I have a good memory but it is incredibly short. So sometimes they get whatever water I have available.
Title: Re: battery bank charging
Post by: glenn-k on January 21, 2007, 10:55:19 AM
How about a rainwater barrel - it will be there for the batteries -- and the mosquitoes. :-/
Title: Re: battery bank charging
Post by: hnash53 on January 21, 2007, 11:58:51 AM
Amanda,

You mention your "meter" which tells you the state your batteries are in.  Exactly what kind of meter are you talking about?

Thanks.
Title: Re: battery bank charging
Post by: glenn-k on January 21, 2007, 02:29:25 PM
One of the best indicators you can get of battery health is a simple hydrometer.  One with the squeeze bulb that samples the acid from each cell.  All cells should show a good charge (usually green) and be very close to each other in readings.  If one cell drops a lot from the rest then that battery is probably not good.  Another thing is a load tester.  Usually a meter with a heater or carbon pile attached.  If the battery shows good the suddenly drops off it also has problems.
Title: Re: battery bank charging
Post by: MountainDon on January 21, 2007, 04:05:35 PM
We'll have to wait to hear from Amanda but since she's living in a trailer I suspect she may have one of the simple voltmeters with a colored scale that are found in most RV's. Some use an array of LED's but it's the same thing wearing a different coat. They give you a general idea of the battery system voltage. But when there's more than one battery involved they become less useful as a bad battery or cell will hide in the crowd.

One more thing about meters that monitor battery voltage. They will give a false high reading if the battery has been on charge within the past couple hours, as well as a false low reading if they've been subjected to a significant load recently. Just FYI.

Glenn is correct in stating a battery hydrometer is the very best tool to use. I used to have one with a built in thermometer so you just had the one instrument. But I broke it. Temps not too important if the batteries are around 65 - 80 degrees, but if very cold or hot a correction should be applied. Also note, that a "real" hydrometer with the calibrated float is vastly superior to those ones with 4 or 5 floating balls.

There is a meter that's kinda cool, works like a fuel level gauge in that it measures the current flow in and out of the battery system. Tri-metric is one.   http://www.bogartengineering.com/    But, because a battery is not a perfect storage medium they have to be programmed and re-programmed as your batteries mature. (polite way of saying get old and worn out). You never get as much power out of the battery as you put in. It's an interesting device, but just one more thing to have to deal with so although I've coveted one, for it's tech value, I don't own one.
Title: Re: battery bank charging
Post by: Amanda_931 on January 22, 2007, 11:16:22 AM
Don's right, the colored light one one built into the trailer--only four different lights.  I can run the 36 LED (dim for all that) bulb for hours without going to the next lower light.  But two days worth of the exhaust fan on when making coffee, and I recharge.

Is that bit from hydrogen appliances right?

Quotestandard automotive alternators are usually putting out 40 to 50 volts into the 12 volt battery in your car. That's right!

Or are they confusing amps with volts?  With a stout battery charger--the kind the service station uses to jump-start you--or Glenn's DC welder--there will be 40+ amps going in probably at 16-18 volts.  And as the battery charges the amps go down.
Title: Re: battery bank charging
Post by: Amanda_931 on January 22, 2007, 11:19:52 AM
Oh, yes, I do put those BT granules in my water tubs and tanks to keep the mosquitoes at bay.  So far they seem to work.  Although crops with BT genes added may make even mosquitoes resistant soon.

(the alternative is to welcome tadpoles--a lot more fun)
Title: Re: battery bank charging
Post by: glenn-k on January 22, 2007, 10:41:39 PM
A couple good points there Amanda.  We have the spring peepers in out pond on top the house.  They keep the mosquitoes out of that one but there are plenty more.

The other is the welder.  As you mentioned - more than about 40 to 60 amps on a big set of batteries could do some damage.  If I run it up to 100 or so I am there watching the voltage.  Welders are not regulated so they will just do as you order them to and fry your batteries. I keep my voltage 29 or less when the welder is on - I have an automatic over charge protection to a point - the overvoltage relay -dump load kicks in and turns on my water pump to lower the excess voltage.  If the welder is too high it will overpower this too.  Do only with extreme caution if you don't want to fry your batteries. :)
Title: Re: battery bank charging
Post by: MountainDon on January 22, 2007, 11:40:18 PM
QuoteThey get low on water and after 4 months of winter.
Whenever the time comes for new batteries you might want to consider AGM sealed batteries. More money but no watering.  :) Around here the tap/pump water leans towards the alkaline, (more and more every year it seems... noticed big changes over the past 22 years. It's good way to neutraize some of that battery acid.  :'(  :(
Title: Re: battery bank charging
Post by: glenn-k on January 24, 2007, 03:11:51 PM
Don, you mentioned a lazy string in a group of paralleled batteries.  I find I can bring them up in 12v groups out of the 24 by individually attaching a standard battery charger to 2 of them (12v) at the center tapped point and charging each half set at a time until they improve.  This is in addition to the normal group charging - I figure if they can get lazy on their own they can be charged on their own also.  Make sense? Ever try that?
Title: Re: battery bank charging
Post by: MountainDon on January 24, 2007, 05:13:19 PM
QuoteDon, you mentioned a lazy string in a group of paralleled batteries.  
Yes, that makes sense. I've done that. That's another nice thing about running a bus instead of a mess of cables; makes it easier. It's just that it's a hassle I'd rather not have to deal with, (already have enough) and the more parallel strings the harder it is to find. For me it's seldom the first one I try, more like the last. Of course, I can rationalize working thru them all by telling myself it's a good thing to do.

The nice thing I like about beiing able to get the amp-hour capacity you want in one series string of bigger (more expensive for sure) cells is [a.] easier to find the problem cell, [b.] fewer cells to water  ;D  [c.] the larger cells will normally, given care, last a veeeery long time.
Title: Re: battery bank charging
Post by: hnash53 on January 26, 2007, 06:52:43 PM
I have built a DC generator using a 60amp Chrysler alternator (externally regulated but I have no regulator attached).  I am measuring 13.2 volts, but shouldn't I be getting more than that since it is unregulated?  An earlier quote in this thread said that car alternators routinely put out 40-50 volts when charging a battery.  Can you explain?

Also, I want to measure the amperage while this generator is running to see how much wattage I am getting out of the generator.  Seems I need some kind of amp meter different than the ones sold at auto parts stores.

Finally, when I hook up this generator to my parallel 12V bank of batteries, do I just connect to any + post and - post to get them charging?

Thanks for all your help.

Hal
Title: Re: battery bank charging
Post by: MountainDon on January 26, 2007, 07:58:00 PM
Quote..........I am measuring 13.2 volts, but shouldn't I be getting more than that since it is unregulated?  An earlier quote in this thread said that car alternators routinely put out 40-50 volts when charging a battery.
Hal
I saw that earlier posting. I was skeptical about that 40 to 50 volts, but I am not an expert on automotive electrical charging systems when it comes down to what's happening.  :-/ That earlier quote referred to a website that stated "a 12 volt battery that is being charged with a wind turbine putting out 50 volts will still only read "12 volts" to a volt meter". I'm a little puzzled by that quote too as I have seen the voltage on my Jeep run all the way up to about 14.4 volts when the battery has been run down. It never sits there at 12 volts when the engine is running. Maybe the website just wasn't spelling it out in enough detail for me.  :-?

My understanding, and I'm not sure where I picked up this info, was that an unregulated auto alternators output would go up to about 18 volts at highest... still too high to prevent damage to a variety things in the auto.   :o

What I'd suggest is you find yourself a good automotive electric shop, one that specializes in rebuilding automotive alternators, not just selling ones in a box. Or maybe one of members here is an auto electric guru.  

I know enough about a lot of stuff to be dangerous.   ::)
Title: Re: battery bank charging
Post by: MountainDon on January 26, 2007, 08:08:31 PM
Quote....measure the amperage while this generator is running to see how much wattage I am getting out of the generator.  Seems I need some kind of amp meter different than the ones sold at auto parts stores.

Finally, when I hook up this generator to my parallel 12V bank of batteries, do I just connect to any + post and - post to get them charging?
The best ammeter would be one that uses a shunt to measure the current flow at the batteries. They have small dia hookup wires to the meter so the meter can be mounted some distance away. The automotive meters require a hookup directly in the positive cable using a cable of sufficient size to carry the expected maximum loads.

As far a hooking a charger up to a 12v parallel string it is sometimes recommended that if you hook up to a "near" positive the negative should then go to the far corner of the parallel array. If you were to connect each 12 volt battery to a heavy duty bus, then just connecting to the + and _ bus bars would be fine.

Hope that helps....

One last thing I did find was a comment by someone who uses an unregulated alternator to charge a 48 volt battery bank. Go to

http://www.fieldlines.com/story/2005/8/14/193535/130  and scroll about 3/5 down the page. Comment by    PaulJ
Title: Re: battery bank charging
Post by: glenn-k on January 26, 2007, 10:31:05 PM
An unregulated alternator can get up to pretty high voltage - seems to be 80 or better as I recall.

It drops down to something higher than the battery it is charging when hooked up and will not read higher than that balance when charging the battery.  Similar to a welder or even solar panels - many will go to 80 volts or more until under load.  Welders commonly read 80 volts or better then drop down to around 20 when under load.  That is why you can seriously blow stuff up if you disconnect your battery on a car when it is running and the alternator is working-- load gets low so volts go way up and smoking things begin to happen - maybe not so much at idle but speed it up and it is almost guaranteed.
Title: Re: battery bank charging
Post by: MountainDon on January 26, 2007, 10:44:55 PM
Thanks for jiggling the grey matter Glenn.  :-[  I do now recall my 24 volt PV panels can easily put out 36 volts (and more) on a cold morning. So if Hal is getting 13.2 without being regulated, he's likely either hooked up to a battery and it's "regulating" the voltage, or the alternator is not working too well.
Title: Re: battery bank charging
Post by: hnash53 on January 27, 2007, 02:17:13 PM
The alternator I am using in my DC generator is a NEWLY rebuilt Chrysler.  When I tested it and got the 13.2 volts, it was hooked up to a battery that was nearly fully charged.  If I disconnected it from my battery, should I be able to read more than 13.2 V?

The battery bank that I have purchased are AGM sealed batteries.  The amp hour rating says 134 AH @ 20 hour rate.  What does that rating mean?
Title: Re: battery bank charging
Post by: MountainDon on January 27, 2007, 02:48:49 PM
Basically Yes, you should see higher volts, especially when run at higher speeds. However, if you have a basically stock alternator, that is with magnetic coils instead of permanent magnets it won't make power unless the magnetic coils are powered. The little I do know about std auto alternators is that they use power from the battery to energize the magnetic field. Once it reached a certain rotational speed it then becomes self powered. A good auto elec tech would know.

If you had a battery that was discharged quite a bit you would see a higher voltage until the battery charge built up.

And I don't know if you will damage anything if you diconnect the battery while running. In a car that would be a disaster for a variety of electronic components.

The amp-hr rating is a way of stating how much energy you have stored. The 134 amp-hr is the amount of work stored. However one thing to remember is that if the battery is rated at 134 and you suck all that power out before recharging the batteries will fail in a short time. For best life using only about 25% of the batteries capacity is best, with std. wet cell batteries.  (going to 50% is okay if not done all the time) The AGM will stand up to a deeper discharge rate than wet cells. Your battery manufacturer's info should detail the proper care and feeding of the ones you have.
.
The 20 hour rate means that if you draw all the power out evenly over 20 hours you will get 134 amp-hours. However, if you draw all the power out over 10 hours the capacity will be less. Conversely if drawn down over a longer period, say 100 hours you will get more capacity out. Think of it like a gas gauge on your car that tells you how many miles you can go, instead of how many gallons you have. The gas gauge says you can go 400 miles at 60 MPH. But if you go 80 MPH you will not go as far; if you go 40 MPH you will go farther
Title: Re: battery bank charging
Post by: glenn-k on January 27, 2007, 10:13:38 PM
Unless that is a internal regulator alternator, you need power to your field.  It won't put out without power to the field but you don't want to leave it energized all the time or it will pull the battery down.  With no regulator and high RPM it may charge but will soon overcharge the battery and burn it up I think - or burn out the alternator.  They are made to charge a fully charged good battery and keep it up but my old electrical repairman was always on my case to get the battery charged before hooking a new alternator to it.  I never did blow one because of not heeding his warnings but you never know -- he was one of the best.

At the very least if you hook a wire to the field, I would have a volt meter on it.  If it gets much over 14 I would get a regulator on it for a 12 volt system.  I'm the guy who charges batteries with  a welder - I've burned up /blown up lots of them over the years.  :-/
Title: Re: battery bank charging
Post by: glenn-k on January 27, 2007, 10:35:27 PM
Try this:

(https://i35.photobucket.com/albums/d184/glennkangiser/21.gif)

http://www.allpar.com/history/mopar/electrical.html
Title: Re: battery bank charging
Post by: hnash53 on February 08, 2007, 07:49:43 PM
OK.  Here's what I ended up with.  I ditched the unregulated Chrysler alternator, and went with a one-wire Delco-Remy alternator (it has a built-in regulator).  No fields to eff with.  Just pos and neg.  The 12 v battery charger works great.

NOW, the label on my AGM sealed batteries says they have a FLOAT CHARGE VALUE OF 13.5-13.8.  What does that mean?

It's my understanding (and my volt meter tells me the same thing) that my alternator is putting out about 16volts.  As long as the batteries can absorb the charge, everything's cool.  But when they get full, how can I know that they are full?

I plan to use a dump regulator to dump the excess charging, such as in summer when the panels are always charging, and dump the excess into a 12V water heater element.

Thanks.
Title: Re: battery bank charging
Post by: JRR on February 08, 2007, 08:09:17 PM
I believe "float charge" is the highest, perhaps optimum, voltage limit that a battery can be charged to before being "overcharged".   Or in other words, it may OK to charge such a battery with a 14 or even a 15, or higher, volt source ... if, after removing the charger, the voltage quickly settles to 13.5 volts.  Of course, temp and current limits have to be also observed.

A lot of science has been recently been done in determining the best current waveform for charging a battery.  "Pulse charging", instead of pure DC, has some promises for lead-acid batteries.   A number of patents have been filed.

Time will tell.
Title: Re: battery bank charging
Post by: glenn-k on February 08, 2007, 11:53:23 PM
After bulk charging an inverter switches to float charge just peaking up the batteries and keeping them there.  A solar guy here told me you want to float charge quite a bit to keep the batteries optimum.  Mine don't see much of it.

QuoteA multi-stage charger first applies a constant current charge, raising the cell voltage to a preset voltage (Stage 1 in Figure 1). Stage 1 takes about 5 hours and the battery is charged to 70%. During the topping charge in Stage 2 that follows, the charge current is gradually reduced as the cell is being saturated. The topping charge takes another 5 hours and is essential for the well being of the battery. If omitted, the battery would eventually lose the ability to accept a full charge. Full charge is attained after the voltage has reached the threshold and the current has dropped to 3% of the rated current or has leveled off. The final Stage 3 is the float charge, which compensates for the self-discharge.

http://www.batteryuniversity.com/partone-13.htm  

I need to read more of the above. :-/
Title: Re: battery bank charging
Post by: glenn-k on February 08, 2007, 11:59:34 PM
QuoteOK.  Here's what I ended up with.  I ditched the unregulated Chrysler alternator, and went with a one-wire Delco-Remy alternator (it has a built-in regulator).  No fields to eff with.  Just pos and neg.  The 12 v battery charger works great.

NOW, the label on my AGM sealed batteries says they have a FLOAT CHARGE VALUE OF 13.5-13.8.  What does that mean?

It's my understanding (and my volt meter tells me the same thing) that my alternator is putting out about 16volts.  As long as the batteries can absorb the charge, everything's cool.  But when they get full, how can I know that they are full?

I plan to use a dump regulator to dump the excess charging, such as in summer when the panels are always charging, and dump the excess into a 12V water heater element.

Thanks.

That Delco is highly recommended in the alternate energy world.  Good deal. :)

The dump  load is great for wind generators as you don't want to unload them - some regulators such as the Trace will just disconnect from the panels and let them go high which is OK also.  The MPPT regulators such as the Outback will put out more power to the batteries from the panels, and also allow higher input voltage allowing a decrease in wire size while still putting out 24v to the batteries.
Title: Re: battery bank charging
Post by: MountainDon on February 09, 2007, 12:18:38 AM
Whoops! I didn't see Glenn's responses coming in!   :)

Quote
NOW, the label on my AGM sealed batteries says they have a FLOAT CHARGE VALUE OF 13.5-13.8.  What does that mean?
The following quote is directed at wet lead-acid batteries. AGM type batteries have slightly different recommendations and may differ between manufacturers. Obtain and use the manufacturers directions. In general AGM batteries can handle higher charging current rates and higher voltages as well. But go by whatever the manufacturer states.

"The first step is bulk charging where up to 80% of the battery energy capacity is replaced by the charger at the maximum voltage and current amp rating of the charger. When the battery voltage reaches 14.4 volts this begins the absorption charge step. This is where the voltage is held at a constant 14.4 volts and the current (amps) declines until the battery is 98% charged. [highlight]Next comes the Float Step. This is a regulated voltage of not more than 13.4 volts and usually less than 1 amp of current. [/highlight]This in time will bring the battery to 100% charged or close to it. The float charge will not boil or heat batteries but will maintain the batteries at 100% readiness and prevent cycling during long term inactivity. [highlight]Some gel cell and AGM batteries may require special settings or chargers.[/highlight]"

QuoteBut when they get full, how can I know that they are full?
The best way is to buy and use a good float hydrometer; not the ones with the balls, but one with a numerically calibrated float. If we're talking about using the home made battery charger gen with the Delco Alternator, the output is regulated. It will should not overcharge.
Title: Re: battery bank charging
Post by: MountainDon on February 09, 2007, 12:19:13 AM
Quote
I plan to use a dump regulator to dump the excess charging, such as in summer when the panels are always charging, and dump the excess into a 12V water heater element.
Thanks.

I don't understand? Power from solar panels is usually routed through a charge controller specifically designed for PV systems. Unlike a windmill they can have the charge power throttled down electronically. They are phenomenally reliable. Depending on the # of 12 volt panels you have you can even get PV controllers that will handle 48 volts and higher and that can cut down on the size of cabling even more. The higher voltages such as 48 VDC are then notched down to match the battery pack voltage.

That's the route my remote system will take.... 48 volt, or maybe 60 depending on some variables not yet settled upon, from the panels to the controller (Outback MX60A) which will be at the battery location. Distance from PV panels to controller/batteries will be approx. 150 feet.
Title: Re: battery bank charging
Post by: glenn-k on February 09, 2007, 01:21:48 AM
Solar panels can get throttled as you say or really gradually disconnected by their regulator.  Wind generators can't be disconnected - they must have some kind of a dump load to burn off the excess power - I pump water by having a set of relays hooked to my dump load of the wind generator along with the excess being throttled.

A wind generator goes wild and may fly apart if not loaded hence the dump load or other way to get rid of the excess generated power.
Title: Re: battery bank charging
Post by: MountainDon on February 09, 2007, 01:27:02 AM
I really wish I had enough reliable wind to make use of a wind charger. But then too, the location is so heavily forested I would need a rather tall tower to get the windmill high enough above the tree tops.  :(

Title: Re: battery bank charging
Post by: glenn-k on February 09, 2007, 01:33:24 AM
About 30 feet minimum to avoid the turbulence but a 100 foot tower will get about three times the wind of a 30 foot tower.
Title: Re: battery bank charging
Post by: MountainDon on February 09, 2007, 02:03:10 AM
That's pretty much what I thought. Maybe someday.    :-/  I'd need at least a 100' tower. Of course then I could put a ham radio antenna up there as well.... Hmmm.
Title: Re: battery bank charging
Post by: youngins on February 09, 2007, 03:48:10 PM
Here you go, Glenn:

(https://i147.photobucket.com/albums/r288/quitesweet/Building/WallMartWindmill.jpg)

Our local Super Wal-Mart is one of two concept stores (the other is in Denver) which testing the use of energy conservation teniques.  They have two other smaller windmills which I think pump irrigation water.
Title: Re: battery bank charging
Post by: glenn-k on February 09, 2007, 10:50:40 PM
That's a start.  Now if only it was against the law for people to not like them or think they don't look nice.  I think we need some legislation. ::)
Title: Re: battery bank charging
Post by: hnash53 on February 09, 2007, 11:20:23 PM
Hey, guys, AGM batteries are SEALED.  There's no way one can test these with a hydrometer.

AS frequently occurs, I'm getting a variety of answers.  And as usual, I'll just have to rely on what I discover for myself.

Thanks for all the help.
Title: Re: battery bank charging
Post by: MountainDon on February 09, 2007, 11:37:54 PM
OOOPs! I'm sorry about that; my error. The only way to tell state of charge with the AGM would be to measure the voltage. That should be done two or three hours after the last charge or discharge so the cells can normalize themselves. That is, they may show higher than they really are after receiving a charge, or lower then they really are after a discharge. Probably not too much of a difference if the load or charge current has not been too high.

Once again, sorry 'bout that.
Title: Re: battery bank charging
Post by: glenn-k on February 09, 2007, 11:57:54 PM
Seems a battery tester - load checker with a heater or carbon pile should show you a bit about how they take a load.  A bad battery will drop off within a few seconds usually.