Just a note on battery recovery - I had one bad cell in one battery in an old group of four of my 2004 batteries.  I rehooked them to my system a week or two ago.  The EDTA recovered a second one in the group that I thought would not come back.

The other battery was shorted and nothing I could do was bringing it back.  I ran a pulse recovery charger on it day and night for several days.  I didn't want to put a new battery in the string so started thinking about some scrap batteries that were given to me.

Dave - you know these batteries .... some very used Trojans..... [ouch]

I had one out of the eight that has been sitting about 6 months or better that it looks like I have been able to fully recover.  It had significantly higher voltage than the rest -about 4.62 as I recall.

I mixed up a quart of rain water and a couple tablespoons of EDTA and split it among the three cells in the Trojan.   I put the Xtreme Recovery 20A pulse charger on it and a companion battery for 12 v.  The companion is the one that had a bad cell and returned from the dead.  By bad cell I mean two cells were 1300 or more SG and one was below 1100.  Point spread in SG over about 25 is not good.  

The point here is that the SG measured with a hydrometer is a measure of cell health and all should be near 1300 on a fully charged battery with little difference in SG.  If a cell is low compared to the others it is time to equalize all cells keeping water levels up above the plates during the process when the good cells will bubble profusely as the bad one is coming up.   Once it is also bubbling profusely and the SG is up then equalization is done.  Refill with rain or distilled water - do not overheat the batteries.  I use the welder to do the equalization but if you are not aware of the procedures (mine) and dangers then again - don't try this at home, kids.

After 24 hours on the Xtreme Recovery charger both the old battery and the used Trojan are over 1300 in all cells.  

As a substitute for the Xtreme Recovery charger, I think that any PWM solar charger will pulse the battery back breaking down the sulfation, or use a desulfator with the charger - just at a slower rate.    Note - just a link that has it - Mikey B of our forum sells them also.  http://www.chargingchargers.com/pulsetech/xcr-20.html

Battery and charging info...     http://www.chargingchargers.com/tutorials/charging.html

 The only pipe I use is 6 inch  with an OD of 6 5/8". A 9 foot section of either the sched 40 or well pipe which is even thicker/stronger is between 200 and 300 pounds.  I say this because offgrid people often want more power over the years and this is a reasonable way to add on over the years. 6 inch sched 40 will support 125 square feet of panels BTW. The 8 inch pipe is only for people like Glen who have heavy equipment service facilities!

I have sent folks down to Costco to buy a golf cart battery for emergency repairs to an L16 bank Glen. It has been very rare with Surrettes.

The best solar exposure I could find is pointing over the roof on one edge of my cabin using a pole top mount.  My plan is to put up a 3" or 4" pipe pole from the ground up along side the cabin and attach it near the eve with a heavy bracket tied back into the studs of the in cabin at multiple points.  If I used a 20' pipe, about 14' of that would be below the attachment near the eve.  6' would be above the eve on top of which I would put PV panels with an area of about 25 sq ft.  I was also considering the possibility of using 2 10' sections of pipe with a coupling as the coupling would be between the eve attachment point and the ground.

The eve attachment would need to be quite robust. With a maximum wind speed of 90 mph there would be approx 30 lb per sq ft force. Times that by 25 sq ft = approx 750 pounds force total.

I'm not an engineer but I suppose the threaded coupled joint would be okay in this case although I'd want to securely connect the pipe to the wall just above the coupling to reduce bending stresses on that point. I would not want to use a threaded coupler an not have the pipe and rack above the joint supporting much weight.

I have 4 threaded couplers on maybe schedule 30 pipe (lighter than standard ) 85 feet tall for my wind generator.  The catch is that I have 4 guy wires every 20 feet to take the side stresses.  My design is based on what I could glean from Bergey Wind Generators information and phone conversation with them.

Good idea on slipping a golf cart battery in there to save the rest of the bank, Dave.  I knew I didn't want to buy a new L16 but the recovered Trojan looks to be doing good now.

20 feet of heavy wall 8" - small potatoes....

http://www.amazon.com/ERICO-611380UPC-Copperbonded-Ground-Rod/dp/B002KAU1X4/ref=pd_sxp_grid_pt_0_1

Looking for ground rods and I found this (as well as others).

The only thing I know about ground rods is that I've had to pound several into the ground (when in mobile switching in the military) and that they provide the 'earth ground' for the system.

From Don's posts and pics it looks like he used two at each location?  Is this required?  We only ever used one in the military.

Anyway, I need to get a couple (or 4) of these and was wondering what your thoughts were?

Also, I have VERY rocky ground and am not certain that I can even get a ground rod down 8 feet!  In fact my well report shows topsoil for FOUR FEET and then granite.  So ya, this might be a little tough.

In that case could a person run several 4 foot rods and make a 'halo' ground system instead?

Lowe's and HD also stock ground rods as should any other supplier who stocks service entrance equipment.  My local stores carry them in the 5/8" diameter, sometimes the 1/2" Cheaper than that one that was posted.  You'll also need a clamp to connect the ground wire to the rod.



According to NEC driving the entire 8 ft length is required, to the point where the clamp on the upper end is actually buried. NEC has alternate grounding methods using a buried perimeter wire. Off hand I do not recall what lengths are required.

I did use two rods at the pole and panels to be sure I had a good solid ground. The soil down there gets quite dry at certain times of the year. Two rods ensures a better ground. See the following post for more....

http://countryplans.com/smf/index.php?topic=6059.msg95643#msg95643

At the cabin and equipment I could have likely got away with a single rod as the grey water leach keeps the earth moisture content higher. But a second rod, clamp and wire was less than $25 and provides extra 'insurance'.

Does your well have a metal casing?  Good ground there.

Quote from: MountainDon on August 20, 2010, 01:45:25 PM
Does your well have a metal casing?  Good ground there.

I was wondering about that Don.  Though the well is about 100 feet from where the panels will be.  How far away can I put the rod (s).

I also have dry ground in the late summer and fall so having two makes sense.  My biggest problem is that where I put the cabin and want to put the solar is quite rocky.  Just digging two feet in some of these areas is nearly impossible without a hoe!  We had to use the winch on the jeep to pull some of the rocks away from the area we dug up for footings and composter.  Was tough.

If I could use the well casing that would help, but again it's a long ways away.

I think I can get a rod or two in within 25 feet of where I'd like them, and perhaps closer but have to explore more.

Thoughts?

Erik

My quick search finds nothing on the distance between the ground rod and the balance of the system.

I did find it listed that a metal well casing on a private well can serve as a ground.

I also found that the 8 foot ground rod can be driven at an angle up to 45 degrees (Cailifornia code item). No mention of angle driving in the NEC or IRC.

I found two grounding systems allowed as alternatives ...

Plate Electrodes

A plate electrode that exposes no less than 2 square feet of surface to exterior soil shall be considered as a grounding electrode. Electrodes of iron or steel plates shall be at least 1⁄4 inch in thickness. Electrodes of nonferrous metal shall be at least 0.06 inch in thickness. Plate electrodes shall be installed not less than 30 inches below the surface of the earth.

Ground Ring Electrodes

A ground ring encircling the building or structure, in direct contact with the earth at a depth below the earth's surface of not less than 2.5 feet, consisting of at least 20 feet of bare copper conductor not smaller than No. 2 shall be considered as a grounding electrode.

Picked up a 5/8" ground rod at Home Depot for under ten bucks   Thanks Don!

I also picked up 20 feet of solid copper #6 (bare) to run from the box to the rod for $11.60.  I figure I can try to put the rod in near where the battery box will be and will have plenty of copper to get to it even if I have to move it 5-10 feet from the box location.

I'll be wiring up the receptacles, lights and switches this trip and installing the main AC load center (bought a Homeline 125amp 8 position 16 circuits) at the same time and landing the circuits.

I pan to run seperate breakers for each area of the cabin limiting each run to 3 boxes and one light or less.  This will give me a breaker for the lower sleeping area, kitchen, refrigerator (assuming I run the camper fridge on AC), 'living' area, small loft, bathroom (1 GFCI -- man those are spendy! and a light) and left and right side of large loft.  Also running one breaker for ceiling fan and one for outdoor porch light.

I figure I can get away with 15amp breakers since these will be light loads and small areas (no more then one overhead light and 3 boxes per breaker) but plan to install 20amp breakers for anywhere that might have a heavier load (kitchen and bath).  12-2 w/ground romex for all but single box runs for desk lamps or clock radios -- which means I can upgrade the breakers to 20amp breakers if need be (which are the same price).

I plan to install at least one outdoor circuit while I'm at it and run a GCFI to the compost unit for the dehydrator and fan.

I've been told that DC likes stranded wire better then solid romex -- any thoughts on that?  The reason I ask is that I was hoping that if the inverter died and I wanted to just change a circuit to 12v I could land the wiring into a seperate box for DC under the AC box.  If not then I'll have to add a run of stranded for the DC circuits if I should want some.

DC lights are spendy but I've read that they are very efficient and draw low power (LED's) so might be a good thing to make use of on my small system.

Any thoughts?

Thanks again!
Erik

First, solid vs stranded wire.

1.  In automotive uses, stranded wire is preferred. Not because it might be better able to carry the currents, but because it is flexible. Being flexible it will not fatigue and break from vibration as readily. It's also easier to run the wires in an auto when they are more flexible.

2.  There is very little difference in the resistance of a solid vs stranded wire in DC applications. So little it is negligible. Solid wire has slightly better performance, less resistance, than stranded wire in DC applications.

Example:
SOLID WIRE
conductor size      12 AWG
area             3.309 mm^2 (square-mm)
area              6530 CM (circular mil)
diameter          80.8 mil (1)
diameter         2.053 mm (1)
DC-resistance   0.00521 Ohm/m


STRANDED WIRE
conductor size      12 AWG
area             3.309 mm^2 (square-mm)
area              6530 CM (circular mil)
diameter          93.3 mil (1)
diameter         2.371 mm (1)
DC-resistance   0.00532 Ohm/m


Notice I stated DC applications. In some AC applications that use high frequency currents, stranded wires offer less resistance and cleaner power.

MY thoughts on DC lighting, as in MY Opinion.

Let me start by stating that my original cabin designs included a lot of DC wiring for DC lighting. I did that because I wanted to avoid the losses involved in using an inverter to supply low currents for AC fluorescent lights. It's true that a large inverter supplying a small amount of AC power to one CFL light may waste a lot of power. Inverters are generally more efficient when working near their rated capacity. My mind was set on using every watt-hour of hard won solar PV power to best advantage. I was not going to throw any power away!

However, by the time I was finished I also had several AC circuits so we could use a variety of AC items, TV, CD player, radio, vacuum, microwave and so on. I had a horrific amount of copper wiring designed in. Some of those AC devices could have been supplanted with a DC device. That would be cool, but they would only be usable on DC. There is also much less selection in DC devices. Plus some of them are crap. (my opinion).

Added to that was the higher cost of DC devices. Add to that the fact that ordinary AC wall switches don't last long on DC power. They fail before the light bulb fails. Add to that if the DC light fails it may be more difficult to obtain a replacement.

So I decided to go virtually all AC. This choice was also made easier because I wanted to have an inverter large enough to run power tools, microwave, etc. without having to worry/think about whether or not anything else was on at the same time. Choosing the 3500 watt Outback inverter provided oodles of power and many frills such as a power standby system that really works well. (Okay, true I spent a bundle on the inverter; more than what I saved on eliminating the 'extra' DC wiring. But that's okay, I feel I won in the trade offs by having the extra AC power available. To my mind I won. )   I used fewer feet of wiring. My AC  CFL lamps are available everywhere and a great pricing. We do have three DC lights. Two are under the kitchen cabinets for counter lighting. I chose them because I wanted to have a couple DC lights inside the cabin just in case the inverter crapped out. Being at the kitchen counter they are more or less centrally located. They are Thinlite RV type Fluorescents. I know they are not NEC approved but so far no inspector has come round.    We also have a DC ceiling fan with electronic speed control.

BUT, I'll add that if I had built a smaller cabin, with less intended use, I very well might have gone with a system that was predominately DC powered with a provision for lesser SC use. maybe I would have done without the microwave, the largest consumer of AC that we have in regular use. Or maybe the generator would be used more?    The way things are are we could pretty much do without the generator at all. Since our solar system went active last year I have only run the generator to

(1)  equalize the batteries (I have also run an equalization cycle once last summer using the PV panels as the power source. That was a great solar day!)

(2)  run the generator just because it had not been run for a month or so.

(3)  assist in heating up the RV interior once in cold weather. The generator ran 2000 watts worth of electric heater for an hour or so.

In my opinion, DC is more trouble than it is worth unless it is a very small system ... except I can't think of anything I would want to mess with it for - oh yeah..... tail lights on my truck....

We need to face the facts..... we are sold out to convenience... throw in a few extra watts to support the slight inverter inefficiencies and quit bothering ourselves with jumping over a dollar to save a dime.... [ouch]


OK - so I'm funnin you a bit but I don't want to mess with DC... 

I'm contemplating moving my inverter and batteries out of the rolling cart (See http://countryplans.com/smf/index.php?topic=4640.20 for pics) under the stair landing and into a more permanent location in the cabin's utility room.  The cart with its AC & DC umbilical cables makes it hard to access the batteries to check the fluid levels.  

My plan is to place each series set of 2 GC batteries on a shelf and run bus bar up the back of this vertical set of shelves to where each pair of GCs would tie to the bus.  I currently have 4 GC batteries total, but will design for 4 shelves for a total of 8 batteries.

My inverter is a 2kw Prosine with 12VDC input.  I currently have everything tied together with 4/0 copper cables.  I have a couple questions.

I like the use of the copper bar jumpers between batteries the Don & Glenn have used.  I was also thinking of using bus bar from the batteries to the bus.  Aside from having to use wrenches to remove the batteries, does anyone see any issues with this?

Don used insulators on his bus.  My + & - bus bars would about 2 feet apart.  Would screwing bus bar directly to kiln dried wood be a problem?

The batteries would be in a room with potential ignition sources, RV water pump, macerator relay, light switch etc.  Should I enclose the battery shelves put a door on it and run a vent out the top the outside, consider a fan for venting while charging, which the Outback charge controller can control or just vent the room to the outside?

I seen mention here of Storm Copper for copper bus, do they sell small quantities or are there other sources?

Lastly, Aluminum bus bar is less than 1/2 the price of copper even though it needs to be bigger than copper for the same current carrying capacity.  Any reason I shouldn't consider using it for the 2 main  buses? 

Thank you!

In no particular order...

Storm copper: their prices on the web all include shipping. They sell any size listed. They will also cut to size, I had them cut the sheet for under the wood stove to the exact size I wanted.  They also have a 800 number and were very helpful over the phone.

I had thought of running bar straps from the battery to the buss, but it seemed like more work to make the connections line up.

Aluminum bus bars. I wouldn't myself, but it can probably be done. Remember there are certain things that must be done when using aluminum in power circuits.

Insulators behind bus bars. For one thing I needed standoffs so I could get the wrench under the bar to tighten the nut and bolt for each connection. A wood block would likely do.

Batteries mixed in with other equipment. I (my opinion) do not like the idea. Batteries do give off hydrogen and oxygen. As well there may be some acidic vapors if the batteries are undergoing a serious charge. I would want to keep the hydrogen away from any potential spark or other ognition sources. Ditto on acid fumes. That's why all my electronics, switches, fuses and breakers are totally separated from the batteries.

Stacking the batteries vertically on shelving does not appeal to me. I want to have enough space above each battery so I can get in there with a hydrometer easily and read the calibrated float easily. I (again, just me) would like to idea of having to lift batteries up above chest or belt level.

You need to minimize the possibility of a wrench, watch band, necklace, whatever from causing a short circuit. That's why I insulated the bus bars over much of their length. I am not sure what the NEC has to say on this. I was/am more comfortable with the insulation since my bars are only inches apart.

If you are playing with different ways to lay out the equipment be sure to not put anything above the batteries. That's NEC as well as common sense.

You could use a positive vent fan for battery venting, but H rises so as long as there is a vent at the uppermost area they should be fine. The Outback CC can also be used to activate venting fans.

Forgive me if I missed it Don!  Having two ground bars or two ground sources is the only way to know if you even have a good ground. The code is 25 ohms or less! I like alot less in the winter and accept that my Kharma will get me though the dry months. I tell my customers to pour 5 gallons of water on it if it looks like a big storm! Set it up so you can check resistance now and then if your area is prone!

I measured between the steel pole, some 5 feet in the ground and the first ground rod and I had quite low ohms. But since the rod and pole were fairly close together I didn't think it counted. I decided two rods would be good/better. Two rods are about 9 -10 feet apart and gave something like 16 between the two rods.

So I guess I ended up with "good" even though all I knew was to aim for 25 ohms or less. I can check by disconnecting the ground wire at one rod and metering between them.  I should probably run a check next time to see what it reads with the ground well saturated, then again in November after things dry out.   

Thanks, Dave. I try hard but am not in the professional league. I appreciate any and all assistance to give to clarify and help keep things safe.

Quote from: MountainDon on August 25, 2010, 03:37:26 PM
I measured between the steel pole, some 5 feet in the ground and the first ground rod and I had quite low ohms. But since the rod and pole were fairly close together I didn't think it counted. I decided two rods would be good/better. Two rods are about 9 -10 feet apart and gave something like 16 between the two rods.

So I guess I ended up with "good" even though all I knew was to aim for 25 ohms or less. I can check by disconnecting the ground wire at one rod and metering between them.  I should probably run a check next time to see what it reads with the ground well saturated, then again in November after things dry out.   

Thanks, Dave. I try hard but am not in the professional league. I appreciate any and all assistance to give to clarify and help keep things safe.

Most all homes and commercial have never had the ground connection checked even when new. Offgrid we always exceed code because we are the power company! The cutting edge of all electronics has always been from from marine and space systems. Offgrid is where we benefit and test it in my opinion!

I just got this in an email concerning the 2011 NEC Code:

2011 NEC® Changes

The 2011 NEC marks an important milestone—100 years of NFPA sponsorship. Throughout its 114-year history, the Code has continued to keep abreast of the state-of-the-art in technology. Major changes to the 2011 NEC focus on the major issue of the day, which is alternative energy. These changes recognize the demand for alternate energy by providing installation requirements that facilitate safe installations.

Covering solar, fuel cell, and green technology is not new for the NEC, but these latest changes in the 2011 edition keep the Code updated to reflect field experience and current technology.

The 2011 Code has revised Article 625 to include plug-in-hybrid vehicle charging systems as equipment that must meet the electrical protection and ventilation requirements of Article 625. In the future, plug-in hybrid vehicles may not only serve as a source of transportation, they may also be able to serve as a power source.

Article 705 is a key article in alternative energy system requirements for systems that interface with a utility source. It covers interconnecting generators, wind turbines, and solar and fuel cells with utility and other power sources. A number of editorial changes were made to improve its usefulness.

Another change to the 2011 NEC is the addition of new Article 694, which provides new requirements for the installation of small wind electric systems. This new article also covers requirements for individual generators that are limited to 100 kW or less. Multiple wind turbines can be used in accordance with this article, as long as no single turbine exceeds 100 kW. This article is patterned in format after Article 690 for photovoltaic systems.

Tickhill

Started generating solar power at the cabin this weekend.    Albeit temporarily.  I took the 2 new 165 watt 35volt panels and set them against a trailer in the sun.  Ran a temporary wire to the Outback FM-60 charge controller.  220 watts max, in a wooded area.  Its amazing to watch the MPPT controller adapt to squeeze the most power out of the panels even when partially shaded.

Don was right, its hard to not keep checking the solar power gen. status on the Outback.

Next weekend the panels get permanently mounted on a 20' 4" post along side the cabin.  Lucked out with the post, stopped by a local welder to ask about having bracket made to brace the (yet to be purchased) post to the cabin and he said his neighbor had a bunch of galvanized 4" schedule 40 pipe for $30 a 20' length.

Reasonable price on the used pipe.

Quote from: TheWire on August 29, 2010, 07:23:40 PM

Don was right, its hard to not keep checking the solar power gen. status on the Outback.

It took about a year and now I glance at it only once in a while. But I do check the daily stats using the Mate inside the cabin.

Has anyone thought about mounting a voltmeter in the combiner box so you could actually fine tune the array for max voltage periodically? I mounted my combiner box and am seriously considering mounting a voltmeter that I can switch in/out of circuit to maximize voltage. Just wondering,
thanks

When it comes to this question my philosophy is "don't sweat the details".

If by fine tune you mean to optimize the horizontal angle and solar south for a particular day/time, what about tomorrow and the day after? What about the day that's cloudy until 4 PM and then the sun comes out for a couple hours? If the power needs were that critical a reliable tracker might be worth looking at.

Our solar system exists to serve us, not the other way around. I make an adjustment a few times of the year to the horizontal angle, maybe 4 changes maximum. That's it. As for pointing it where the sun should be in an east to west sweep, I picked more or less solar noon. We haven't had to run the generator tp make up for it yet.