Building Tips – Batteries Can Self Destruct

. . . . as Steve M can attest. 

A few of us were down at Spencer’s one Sunday running a variety of models. I ran my Tempo hydroplane for about 5 minutes at one point. It ran well on two 7.4 volt Li-Po batteries that are wired up in series to deliver 14.8 volts to the motor. I’ve used two 3 cell Li-Pos in the past but that is too fast for Spencer’s.

Finished the run and brought the boat in and lifted off the hatch. The motor was cool and the batteries only slightly warm so it was a good run.

I heard a hissing and suddenly there was a dense cloud of grey smoke pouring out of the Tempo and a flicker of flame. Ken grabbed the battery out of the model and tossed it onto the ground where it burst into flames.A quick dowse of coffee put out the flames and the excitement was over.

Quite unexpected and puzzling. I slow charge the batteries so they are not subject to stress during charging. The battery was one of a set of two that I have had for 3 years I think. I have used the set of two either as a matched set in the Tempo or as singles, but almost always with brushed motors which are actually supposed to be easier on the batteries.

A caution to all members to be careful of how they store their LiPos and beyond that I am still at a loss to explain what happened to me so all thoughts and ideas are welcome.

Some just smoke and sizzle . .

On the same day that Steve reported the above, Roy was desoldering a pack of NiMH cells to remove a dead one. For no apparent reason one started to smoke and sizzle. It was held in a rubber-jawed vice at the time, and the jaws suffered no ill effects. The photo shows that the cell had expanded and split its wrapper.