Battery bank setup

This photo is from when I first started out with this crap in my garage. I wondered if I could hook up the Xantrex 400 plus that I had to larger batteries. It worked, so I started experimenting with alternative energy. At first I charged the batteries with the car and then bought the solar panels. I used an old Fed-ex delivery box for the batteries and a Xantrex 400 Plus powerpack as the inverter.

Well, this is some of junk I ran for my first tests back in the winter of 2005-2006. The laptop is on the top step of the ladder and a small fan is on the bottom step. I used these because the draw from each is known and constant. I was able to use this test to size the original battery bank. As it turns out, I was within 10% and the addition of an additional deep cycle brought us up to snuff.

This is the old Xantrex 400 plus that we started out with. I still have the thing kicking around here somewhere in case of an emergency.

Updated 7-1-10

Also see about the system.

The above photo is what our battery bank box looked like as it was being built.

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The photos at the right are pretty old and are from when were bench testing and designing the system. they need some serious updating. 

Tip: when designing your system keep in mind that you never, never, never drain a battery more than 50% unless it's a nuclear attack, war has broken out, Stephen King novel emergency. So take your battery bank amp hour size and cut it in half. The reason is that several things happen to a deep cycle battery when you get to around a 50% level of charge. Most notably is that the battery begins to sulfate which is a condition that keeps the battery from getting to a full charge and shortens the length of time you can use the battery.

Any off grid power system has a way to store the electrical potential for use at a later time. Batteries. Deep cycle batteries (doesn't matter what flavor - flooded, AGM, dry, whatever) make up the energy storage system. If you've done any research at all before you got here you already know that batteries do not store electricity. They store the chemical potential for producing electricity.

Our first bank consisted of 3 group 27 batteries made by Exide at 79 amp hours each. Sadly, there were the maintenance free type and were spent, used up, done, cooked, dead, stick a fork in them done this past spring (2010). So we used them as cores for two brand new group 31 Transcontinental (East Penn) 120 amp hour batteries.

For my money using group 31 batteries is far better than the smaller group 24 or 27 batteries. For about the same cost you get a lot more bang for your buck both in life and capacity.

So after starting out with a 237 amp hour battery bank, we now have two banks that we use. The primary battery bank consists of 3 group 31 (110 amp hours each) deep cycles - 330 amp hours - and these guys are starting their 4th year of service. We've sulfated them on purpose so we could find out how to fix them - you can read about that in one of our diary entries - ran them to 11 volts several times, charged them at some incredible rates, charged them too slow just to name a few ways that we've found to abuse them in the name of entertainment.

The good news is they are performing within 15% of their new condition. 

Our second and brand spanking new (I love that new battery smell) East Penn deep cycles have each gone through exactly one charge/drain cycle. They're 120 amp hours each for 220 amp hours. We're going to test these things all summer and if they work out we'll be purchasing up to 20 more of them for the next step; our massive charge it once a month battery bank.

Here's the dirty secret about deep cycle batteries. They take 30-50 charge/drain cycles to reach their full capacity! That's right those new deep cycle that you have are not working like you thought they would because they won't for a while yet.

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