Swollen NiMh Battery pack

[lord filbuster]

Any idea what could cause this?

I'd just finished cleaning the barrel of my AUG, so i fired a couple of hundred rounds at a target in the garden, to reset the hopup. I only fired semi auto so i would think i stressed the battery that much. Anyway, after taking the battery pack out, i noticed that one of the cells in the battery pack had swollen quite a lot. I didn't notice any problems when shooting, and it didn't feel that hot, so it gave me a bit of a shock.

Anybody else had this sort of thing happen to them?

I guess its new battery time anyway.

[JerseyRider]

My guess is the way you charged it can you shed some light on how you charged it

[lord filbuster]

Just the basic 'dumb' charger that came with the gun i'm afraid.

Actually thinking about it, i suspect you are right. I calculated the charge time based on a flat battery, it may well have been half charged already, doh.

Oh well, time to buy a smart charger + battery. At least the gun isn't damaged.

[Deva]

Is it still swollen? You're probably alright just getting the smart charger, assuming the battery is okay. It isn't like it's a LiPo so you don't have to worry about fires etc. Also if you took it straight off charge and put it straight in the gun then it's likely to cause it to warm up even more so, and obviously therefore swell up.

[JerseyRider]

Just a note this is what happens if you "miss use" a LiPo

 

[lord filbuster]

I had a look at it with a multimeter, looks like it is still developing the right voltage, and i think it has just vented and resealed itself.

[Deva]

I reckon it'll be fine, grab yourself a decent smart charger, stick it on and don't charge above 1C (ie for a 2000mah battery don't charge over 2A or 3200 not over 3.2A etc) if it warms up during charging let it cool down before you use it and then see how it behaves.

 

I'd also recommend fitting deans plugs if you are confident at soldering.