I just scored eight used 12V 26Ah sealed lead acid batteries, which I hope to do some experimenting with. I'm not entirely sure how good they are, so I'll need to charge them up and do some kind of discharge test to rate them. What I want to do is to try them out in different configurations of series/parallel between 12V 208Ah and 48V 52Ah, (as a small scale off-grid test). I'd like to come up with one charging system to cover all configurations. I don't mind building one if I can get a good schematic, or buying one if it's not too expensive.

Any recommendations?

Well if you're looking at making one, I'd suggest finding a 120 in with x4 12V out. That way you can rec then and have a high current 12V out, or with some trick use of relays have a medium current 24V out, or a 48V out. That way you can charge 4 of them independently from each other, or hook them in series and charge them at 48V.

You can guess-imate the internal resistance of the battery, then you can calculate the voltage needed to charge the batteries at the maximum current the batteries can handle.


If need be, I can check when I get to work tomm, and see costs. I'd guess you'd look at about $200 (USD) to build one. You can make one cheaper if using second hand parts, but new parts should be around $200.

A simple charger shouldn't be too complicated.

From the battery spec. sheet:



And its internal resistance is listed as 10milliohms when fully charged.

I could never design an electronic circuit, but I could build one if someone pointed me in the right direction. $200 would be stretching the budget a little thin, how much easier would it make things if I restricted it to 24V?

Well you can find 12V/24V chargers for cheap these days. You might be better off ebaying if you want the easy way out .
Shoot, you could get a 12V x 2A charger for less than $20 these days. Now it would take a while to charge (about 12 hours) but thats the trade off.

Or you might be able to find one for 48V at 2A, but it would still take about 12 hours or so to charge.

Look HERE, I've bought from them before, their pretty good (only bought 1 thing before). Their prices are not bad either. I think they sell overstock power supplies, thats why the prices are so cheap.

You could always connect them in series, short the terminals and see some top notch explosives fireworks.

Ahh, reminds me of my high-school days. I used to link 9V batteries in series to equal ~150VDC. Then with careful use of alligator clips attached to two pencil leads, you could briefly touch the leads together, and as you pull them apart you could get about a 1" DC arc. Just hissing away.

Wow, looking back I did a bunch of things that could have killed me.