A123 packs are seriously tolerant... I think?

[Webbage]

Okay dumbass of the week award is already here, the pointy 'D' hat is firmly sat on my head. :\ :whhooo:

I left my A123 pack plugged into my Axial. I usually religiously unplug them every use but somehow it got forgotten. Anyhoo I'm goin out to morrow if the weather's okay (gonna be cold but should be clear), so I put all my packs on to top up. I cam to the one off my Axial and my Hyperion gave me a low voltage warning. Oh crap. I metered it and it was sat at 2.1V. For a 3S pack that's really low. I tried disconnecting the balance lead, and hooked it up and tried it at 2S and it wouldn't go, and at 1S it peaked almost straight away. I figured I had to inject some charge in somehow, just to wake it up.

I did something very dangerous to it then and I'm not even gonna post what I did.

I set it back to LiFe and it wa straight away registering 7.21V. I plugged th balancer back in and set it going and it happily pumped 1062 mAh into the pack and it balanced out at 3.71V per cell. I checked it regularly and it's nominal temperature, no abnormal signs at all. I'll see how it runs tomorrow.

That's some Lithium battery that can take that and still come out fighting. A LiPo would have been straight into the dead battery hard-box. The more I use LiFe the more I like em

 

[olds97_lss]

I recently had a similar issue, but on a much smaller scale and with my micro-t NiMH stock battery. I wanted to play with it and see if anything was wrong with it, since winter is here. So, I go buy new AA's, put them in the charger, plug the charger in, no red light (should light when charging). Fiddle around with it for 15 minutes before it dawns on me that it was still plugged in to the truck when I started... sure enough, flip the truck over and it's switch is set to on. Been on for 3 months. So, I check the V of the pack and it reads .01v on my multi-meter.

I tried plugging it into my "real" charger (MRC 959) hoping it can sense that a battery is actually connected... nope, same issue. Doesn't acknowledge it.

So, since it's such a small pack and they are fairly cheap, I figured I'd hot wire it to another 4.8V source, some fully charged NiMH AA's in a 4 cell pack I use for charging camera batteries. I wired it up and plugged the AA's into the little pack and let it sit there for about 15-20 seconds. Sure enough, plug it back into the stock charger and the light lights up and it takes a charge. Also charged it 4-5 times on my real charger (which I had never done until that day) and it charges it quicker and seemingly better.

I can only guess that you tried something similar. Glad yours didn't blow up in your face either!

 

[Webbage]

You probably weren't at risk of popping that pack, NiMH isn't volatile like Lithium batteries.

Well seeing as you told everyone what you did, I'll spill but I DO NOT RECOMMEND THIS TO ANYONE. Absolutely under NO CIRCUMSTANCES should this be done with LiPo. The A123 LiFePO4 packs can take the beating, LiPo can't. I'd not even have considered doing it to a LiPo.

I switched the charger over to NiMH mode (7.2V) and gave it a 2 second shot at 4Amps. The voltage went up really fast so I shut it off after 2 secs. I flipped the charger back over to LiFe, plugged the balance board in and bingo. It picked up at 7.45V and charged from there quite happily.

KIDS (AND GROWN UPS) DON'T TRY THIS AT HOME. If you screw it up and it throws too much beans at the pack it could go bang. AGAIN it's absolutely not safe to do this to a LiPo. I was using A123, NOT LiPo.

I just tried the pack and it's going like it always has. I remembered to unplug it this time though