[Dr Fly]

Hang on, lets get some fact into this. statements like, "do not balance charge" can be misleading, and cause much more swelling if people dont get the context of it

Whilst there is not any real need to balance charge a pack every time, it takes several charge/discharge cycles for a pack to go out of balance. There is also no harm being done when you balance charge a battery. You have much higher chance of damaging a pack by non-balance charging an out of balance pack. Than balance charging every time.

Swelling is caused when you get oxidation of the internal Anode and Cathode of the battery. This can be caused by internal contamination (poor manufacturing) high current charge and discharge. Exceeding the voltage limits of the pack, and also by too much heat.

Exactly what causes your pack to degrade is entirely down to your own circumstances, every pack in this thread could have a different problem, or they all could be from the same batch, who knows. But once a cell starts to degrade, it will only get worse and worse, as the reduced performance will cause more oxidation.

Personally, I use LRP (2 years old), Reedy (1 year old), Losi (3 years old), Thunder-power (3 years old) and Nano-Tech (3 years old) packs. I dont take very good care of them. I balance charge everything at 6amps, which is the max of my charger. I throw them in a car run my five minute race, then throw them back in a box. on a race day i use 2 packs, one on charge, and one in the car. I never storage charge.

The only swelling in any packs is from one of the LRP ones, which i left fully charged by mistake for several weeks. The losi and thunderpower packs are now on there way out, in that the internal resistance is so high, that the voltage drops under acceleration that the car goes into limp mode. This means the pack has got to the end of its racing life, but still no swelling.

If i had issues with several cells all puffing up, i would start to check my charger cut off limits, i would also look at the way i use my cells compared to others. Belive it or not, we had a guy in the club Who's charger cut off voltage was so out of calibration, that it popped open a brand new pair of saddles.

Also check the temp that your batteries are coming off the track, are they hotter than others? All these things add up, and all cause swelling.