Well, the small ones are pretty bomb proof. Normally they need a direct
short to burst into flames, as in the famous video where a nail gun is used
to do the deed. Just heating, unless its really far too much for the rest of
the device is unlikely to do it as many do run hot if charged quickly. Can
you not replace the batteries. I know that they do not last for ever, as
they put the same ones in some mp3 players as well.
Brian

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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Bill" wrote in message
...
I have a couple of dashcams, both of which have internal batteries. Both
have worked well and neither has, as predicted online, exploded in the sun.

Both vehicles have permanently on cigar lighter sockets, and I used to
leave the cams to fall into parking mode - 1 frame per second.

This year both internal batteries have failed, and I'm now feeding each
via usb adapters that measure the current taken, voltages etc. This has
slightly alarmed me with the ddPai cam, which is taking 0.6A at 5 volts in
either mode in a car that I'm using less, and is pulling the main battery
voltage down to about 11.5 volts or less at the end of a few days of
little use. The cheaper cam takes 0.2A.

The question isn't that, though. As summer may be coming, I'm thinking
again about the dangers of leaving these things powered up in hot sun.

Is the thermal runaway that causes these lithium batteries to swell and
burn not likely to occur in an electrically dead battery or is it a
chemical effect that occurs with or without volts present?


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Bill