SLA Tester for 12ah and 20ah Batteries

[carbon.nanotube.capacitor]

I was wondering if anyone has experience with digital SLA testers. I remeber using one at a shop once that worked well, except that it always estimated the capacity of 12ah batteries to be full, even when they were near-dead. I don't remember the brand, just that it was hand-held and orange. What I'd like is a digital one that is accurate even for smaller batteries. At the moment I am using a 500 Amp load tester and reading the voltage before, during, and after load. Small batteries are difficult to measure this way - even 12ah sizes are too small really, although it works fine for liquid starter batteries.

Any ideas or recomendations would be appreciated.

[usatracy]

We have used the West Mountain Radio CBA II

Base unit is only 100 bucks and can test 3 volt cells to 18.8 amps and 12 volt batteries to about 8 amps

They have an expansion unit to allow serious testing at much higher loads but that adds over 600 to the cost.

Uses USB to a PC to control the testing and allows some configuration of the testing and safety cutoffs based on low voltage and/or temperature.

Its a nice toy, would be nice if the expansion unit ws not so much more money though...

http://www.westmountainradio.com/CBA_ham.htm

Here are some tests and graphs we produced using that unit on Thundersky cells

http://www.voltsrider.net/vr/forum_posts.asp?TID=179

[usatracy]

At the moment I am using a 500 Amp load tester and reading the voltage before, during, and after load. Small batteries are difficult to measure this way - even 12ah sizes are too small really, although it works fine for liquid starter batteries.

We have tried that (10 second load testers) and found it seriously lacking in find the true capacity of a EV deep cycle battery which was important for us since the pack of 5 batteries in our 60 volt string can only go as far as the weakest battery, using either a PakTrakr and riding the bike, or, the CBA II and performing a load test, have proven to be the only sure fire ways to make sure the pack is healthy and trouble free.

If someone had a silver bullet 10 second test we would be interested too, but so far, it seems you need to really put a little time and discharge into it if you want to have piece of mind that the pack is in tip tip shape.

Those high amp load testers exists to prove a battery can provide hi amp starting capacity for starter motors, and aren't really the thing to use to determine if a battery has the deep stores for lower amp long time drain capablity.

We took a silicone battery in Sep 2007 that had only 30% of its capacity left, used a starter load tester, the battery passed the test with flying colors, but could only power an EV for 2 miles instead of 23.