burtona

My Feedback: (50)

I've got a couple of Zippy and FliteMax 5000 10S packs that are getting soft and puffed up. Both packs charge OK and fly the 2M planes OK. At what point should I stop using them? When do the become unsafe to charge? Ive been using these packs regularly for about 2 years now. I don't keep records on them so I don't know how many cycles they have been through. Any battery experts out there that can help me know when to stop using and dispose of them?
Dave Burton

DaveL322

Dave,

Without removing the heatshrink, it can often be hard to tell if the cells are really puffed, or it is trapped air. I would say it it more important to track the cell balance...almost all lipo packs will get "squishy" with age to some extent, and many will also increase slightly in volume.

If the balance on the packs is good at the end of charging and the end of flying, I'd keep running them. If you can measure IR, also keep an eye out for IR readings of a single cell that is substantially higher than the others - if you see that, the pack is not going to last much longer.

REgards,

mithrandir

My Feedback: (2)

all my flightmax are Perma-Puffed.. after about 30 flights they started this.......

burtona

My Feedback: (50)

Thanks Dave,
I'll start checking the IR and balance and see how they look. Inless I see something out of line I'll just keep using them.
Dave. I

mups53

My Feedback: (41)

I agree with Dave. Monitor the IR's they tell all. I have soft packs that have 150 flights on them that work perfect. I think the chemicals in some Lipo's are different than others. Its probably the way they activate under use. Mike

smcharg

My Feedback: (1)

Dave L.,
What is considered "significantly higher"? Are we talking a cell that's .5 higher or 5 higher or are we talking a percentage?

Thanks,
Scott

DaveL322

Good question....from my experience, the IR readings from most chargers are not really accurate or precise. When the IRs are very low, 1 vs 2 is obviously a huge percentage, but not something that indicates a problem (in my experience). 10 vs 20 on the other hand is indicative of a problem, as would be 5 vs 10. At what point it is really a problem? Probably depends to an extent on how hard the packs are being run (discharge rate, ambient temp, depth of discharge) and I would be increasingly concerned about the IR difference when accompanied with cell imbalance and 130F + temps on the lipo after a flight.

Regards,

smcharg

My Feedback: (1)

Excellent information.  Thank you