For smaller cells like A123 there is some pretty good off the shelf RC chargers with capacity testing built in. I purchased a Superbrain 989 a few years ago, and I think it does all the same things you just described. http://www.modelrectifier.com/search/product-view.asp?ID=6863
It does have some limits that don't work as well for higher capacity cells, and even though it claims a 10 amp discharge rate in the testing that I used it for which was 6 cell nimh sticks out of a Honda Insight it seemed to derate back to about 6 amp discharges. Higher voltages would probably cut back even more as it probably can't shed the heat fast enough.
damon
> From: xxx@xxx.xxx
> To: xxx@xxx.xxx.edu
> Date: Sun, 8 Jul 2012 12:38:20 -0700
> Subject: [EVDL] I build a low cost battery tester - yeah!
>
> So I revised my first significant circuit board slightly and wrote some
> software and am now testing my a123 batteries to find 16 to repair 2SSIC.
>
> It is working well. The alligator clip attached is hooked up to a buzzer so
> that I know when it is time to put the next batteries in.
>
> It charges the batteries to set, stabilized voltage, discharges them
> measuring time and current, and then recharges them. Takes about 3 hours
> per set right now (1c charge discharge rate).
>
> Screen has a counter telling me everything is working, current voltages of
> all the batteries, and when finished amp hours (with 2 implied decimal
> places) and time to discharge for each battery.
>
> It is giving me predicted results, which is to say the batteries that have
> like 2 cycles on them are showing a little over 2.3 amp hours and the
> batteries pulled from car are showing a little over 1.8 amp hours. So 4
> years of abuse = 78% original capacity.
>
> I'm thinking about building a mark 2 version of the tester, make not almost
> entirely out of parts I have laying around. Something nice looking, much
> faster on switches, and producible. I've designed it to be very cheap and
> I'm wondering anyone else wants them.
>
> With a kind of cool acrylic case, small display, button, USB connector with
> virtual serial port I think I could sell a 4 cell unit for $75 or a 8 cell
> for $125 plus cost of charging 5-6 volt supply if you don't have one.
>
> I could also write software to do cycle tests and give you average, min, and
> max pretty easily. The case would hold 18650's, and 26650's and I could put
> something on to connect other batteries to it. The hardware software would
> be able to charge from 1- 4.4 volts, discharge to .25-4.3 volts.
>
> I have a lot of batteries to go through (all of the batteries from the
> GreenT that survived being sprayed with water based fire extinguishers), So
> I'm going to be building a second one. I'm just thinking about how much
> effort to put into it
>
> More pictures at http://picasaweb.google.com/SSIRacing/BatteryTester
>
> Michael "KD" "TRex"
> Not posting enough,
> Not racing enough,
> www.SSI-Racing.com
>
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[EVDL] I build a low cost battery tester - yeah!
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