Lithium cell tests

[terrorhurtz]

Yup, looks like the A123s are taking the abuse.
400 cycles, proably regularly over-charging cells at very high currents and only 11% capacity drop. 400 cycles... probably at least four years of fights for the average robot.

The Zip charging (basically just fast charging with a power source voltage matched to the pack voltage) is probably only suitable for 3 or 6 cells. Who wants to carry around 3 car batteries? Or even one... and you have to re-charge the car battery at some stage.

Probably only really worth it if you really need to charge in 6 mins.

But then we generally re-charge our A123s in less than 10 mins (at 5 Amps), because we dont take that much out of them.

We use a cheap 48V, 10Amp power supply (to charge two 10s packs), a light bulb for each pack to limit the current and a dapter for each pack as a voltage cutoff. The dapter is similar to the Terminator but can handle up to 10 cells at up to 10 Amps - http://www.slkelectronics.com/lipodapter/http://www.slkelectronics.com/lipodapter/
But we try to make sure the packs are well balanced before each competition.

I find that the packs tend to go out of balance when left for a while, so best to balance them right before an event.

[typhoon_driver]

Thanks for putting it all into perspective John.

I am very glad to see that the A123s are up to taking the demands of robotic combat!