battery bank charging

[Amanda_931]

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.

[MountainDon]

25% 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.

[glenn-k]

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. :-/

[desdawg]

[glenn-k]

You ought to try it some time desdawg - lots of fun -- and works if you do it right.

[desdawg]

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.

[glenn-k]

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.

[MountainDon]

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  :'(  )  

[desdawg]

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.

[glenn-k]

How about a rainwater barrel - it will be there for the batteries -- and the mosquitoes. :-/

[hnash53]

Amanda,

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

Thanks.

[glenn-k]

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.

[MountainDon]

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.

[Amanda_931]

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?

standard 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.

[Amanda_931]

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)

[glenn-k]

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.

[MountainDon]

They 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.  :'(  

[glenn-k]

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?

[MountainDon]

Don, 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    [c.] the larger cells will normally, given care, last a veeeery long time.

[hnash53]

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

[MountainDon]

..........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.  

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.  

[MountainDon]

....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

[glenn-k]

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.

[MountainDon]

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.

[hnash53]

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?