Batteries for solar setup

[SamuelA.]

Can anyone recommend an inexpensive battery system for a solar set up?

[woodisgood]

I've heard of T-105's being used

[rreidnauer]

While not ideal, Uninterpretable Power Supply (UPS) batteries can often be gotten for free. I work for at an office for a telephone company who has some medium sized UPS's (40 batteries in the one, 80 in the other) to keep the computers going during the time when the grid fails and the generator picks up. Anyhow, I asked the guy changing the batteries out (which get swapped out every 4~5 years, just for CYA reasons) what they do with the old ones. He say they go to a salvage plant. I asked if it would be possible to get the batteries, and he had no objection.

Now, the batteries are not the deep cycle type, but if you use enough of them, you'd be working them pretty light. I'm sure if you find a UPS servicer/installer, he can get you into batteries.

[ChainsawGrandpa]

About six months ago I decided that lead acid batteries had too many
draw-backs. Spent a lot of time researching Ni-Cads (nope), Li-ion (not
too bad, but a lot of money and the high density to dollars wasn't worth
it), NiMH (very good, but still a lot of dollars). 6V golf cart batteries, 12V
trolling motor batteries, AGM, Rolls Surrette....

After an intense day or two of research I discovered the biggest bang
for the buck was the Trojan T-105 with after market vent caps. Not ideal,
but the price is right, and the headaches minimal. At the time the best
price was about $87 + shipping. I don't know why (the numbers sure don't
explain anything) but a six volt 225 Ah Trojan has more life and bang-for-
the-buck than a 12V 1100 Ah trolling motor battery. That sure doesn't
make any sense to me. Was almost sold on the 12V 1,100 Ah (900 - 950
rated)trolling motor battery from Costco or WalMart ($67), but the cost per
Ah is better w/ the Trojan T-105.
Can anyone explain this? Any other suggestions?

-Rick

[jjohn]

Rick,

The t-105s work ok, and as you have found are the best bang for the buck in the lead acid category. Just this week I hooked up 10 t105s to replace a bank of 105s I hooked up about 4.5-5 years ago (not mine). The original bank from 5 years ago started out as larger than the 10 we are replacing it with.
Over time a number of the batteries failed.
I think it may have had to do with the way I hooked up the first set, I am suspecting that they became imbalanced when being charged, and discharged. I hooked them up originally in the typical series// combination with the output cabes to the inverter hooked up to the last batteries in the // string, this was also where I hooked up the output from the charge controler (for the solar). It all made sense, and worked fine at the time.
This new set is being hooked up so that the positive inverter input cable is hooked to the positive battery teminal of the last battery on the far (upper) right. The negative cable going to the inverter is hooked up on the (diagonally opposite side) last battery at the far lower left corner. This should compensate for the unequal cable losses in the // strings. Causeing the inverter to draw more evenly from the batteries.
The charging input will be hooked up to the other two outside terminals (+/-)
on the far left, and far right of the battery bank, and this should then charge them more evenly, or so I hope.
Just thought I would mention this, I am learning by trial and error so to speak, wont really now how much this helps for about 5 years. If I am not clear, or if you wish I can always take a pic.
Did you consider Nickel Iron batteries? With the shipping from California the cost might be 3x lead acid prices, but it would be the last battery you should ever have to buy.

John

[rreidnauer]

It's actually very simple. They have much heavier electrode plates.

All lead-acid batteries erode away the plates over time, no matter how nice you treat them. That's just a fact of life, and why they have a limited lifespan. So the heavier the plates, the longer they will last. Usually (if the battery hasn't been killed by undercharging and sulphated) the thing that eventually does them in, is a short in the plates when a piece of one breaks off and bridges two plates. Technically, the battery is still works, but at a lower voltage. Also, high quality batteries typically have a deeper "sump" for such pieces to fall down into, hopefully extending the batteries life a bit longer.