RE-Building A123 Packs

[JThiessen]

Measuring them was easy. Thats how I figured out which were bad and which were good.

Now on to how to fix them. If I can figure out how to charge those cells without taking the whole thing apart, I'd be really happy.

[lincpimp]

Originally Posted by JThiessen

Measuring them was easy. Thats how I figured out which were bad and which were good.

Now on to how to fix them. If I can figure out how to charge those cells without taking the whole thing apart, I'd be really happy.

The paralled cells will have to be seperated at least on one end to charge. Some small alligator clips work well, that is what I use to charge individual lipos.

[JThiessen]

I put one cell on the charger, and it looked like it was going good, got it up to about 1.2V, and then the charger gave that "output voltage too low" error again. Wish i knew what that was all about (the manual doesnt say anything). BTW, had the Duo set on A123, 3.3V, 2300maH, .5amp.

Guess this could be the bad cell.

[JThiessen]

Just to update, I got one of the cells up to 3.3XX volts. I'll be trying the other one tomorrow. With the Hyperion Charger, about every 5 minutes it would give the "output voltage too low" error. I just reset it again and again until after it hit about 3 volts, then it started working fine. Its been sitting on the last one now for about an hour, and seems to have stabilized.

After seeing how this happened, I took one of my other "bad" packs and charged it on Nimh up to about 4 volts. Then I put it on A123 and just kept resetting it. Its now up to 5.2V. There are no hot spots on the pack, so it doesnt appear that I'm overcharging any one cell.....

[tc3_racer_001]

good to hear! one of my a123 racing packs, i added balance tabs on them only reads up to 3.37v... while the other one just bleeds off the extra current/voltage. one good thing i guess rather than overcharing the other pack!! i would suggest adding taps if you havent already to get them balanced.

[JThiessen]

I added Hyperion taps last week.

To update: The pack that I though I was able to rescue may infact still need to be torn down. I've been able to get it up to 6.6V charging without the balancer, then I pull it off, and rehook it back up and balance charge it. The "bad" cells still drop off to about 2 volts before it gets to the charging part of the process. I've gone through this process twice so far - I'll give it a couple more tries before I give up on it.