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Charging LiPo with Wall-wart

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Swelling is not normal at all. Swelling is a sign of the battery being over charged or over discharged. In your case based on what you wrote, likely an over discharge. During charge or discharge it is normal for the battryies to get warm but not hot as you describe. The heat is a sign of over charge or discharge and is what is causing the swelling. There is a pressure build up. Since I have no clue what the individual cell voltages are or what is going on inside your batteries what I have mentioned is as good as it gets. Also, I believe I mentioned earlier that a good LiPo system often mmonitors temperature during charge cycles. Swelling and excessive heat are not normal.

Ron
 
:S:S
Just came back from a flight, the usual swelling, no more no less

One battery is @ 11.04V, the cells: 3.67V 3.69V 3.68V
the other is @ 10.85V, the cells: 3.62V 3.67V 3.58V

During charge nothing unusual happens, no heat no swelling no nothing
The charger charges till 12.42V which gives 4.14V/cell, after charge they're all perfectly balanced...
 
Right. The reason that your batteries are swelling is because you are drawing too much current from them. Lips have a C rating - if your 2200mah batteries are 10C, then you can draw 22A from them. If you draw more, the cells can't provide the current, they heat up and swell. This is very dangerous and can led to an explosion - you need to get some new 20C or higher batteries before something bad happens (eg a fire).

Andrew
 
A defective or overloaded Li-Po cell gets hot and swells.

They tested small Li-Po cells on www.rcgroups.com . Cheap poor quality ones had a high internal resistance which dropped their output voltage under load and caused them to get hot (but they did not swell). Only one brand called Hyperion had a low internal resistance and produced a higher output voltage when loaded so it was much more powerful than the cheap ones and it did not get hot.
 
As audioguru says, your batteries cannot handle the discharge current due to a high internal resistance.

If you are drawing about 20A, then I would esitmate the C rating of your batteries to be around 6C or 7C. They are certainly not the advertised 20C.

What brand batteries are they? Unknown brands or unbranded batteries (often sold through ebay) tend to be very optimisic about the C ratings.

A
 
The batteries are KDS: www.kdsmodel.com, same brand as the helicopter
I think it's a good brand because the shop sells nothing in the 450 range apart from these. They even stock all its parts.

The heli comes with a 1800mAh 15C battery, but at the time of purchase it was puffed so the dealer replaced it with the 2200mAh 20C; heh makes me think what would've happened if that battery was in salable condition.

Anyways, guess I should have a talk with the dealer.
 
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