Batteries in Dashcams

[Bill]

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?

[Brian Gaff]

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

[Bill]

In message , Brian Gaff writes

Brian, There are pictures of the type I have at

They show a camera whose battery has left this earth.

This cam looks difficult to get into, and, behind the windscreen in the sun, it gets too hot to touch. It is said to have a battery which shuts down at over 70 degrees C, but looks standard. However, there are warnings about cheap copies of these batteries, and the ones on ebay and elsewhere would all have to have the connector from the old batt swapped.

The camera seems to work OK with bad battery, soit is really a question of whether it would be safer to try to crack the thing open and pull the battery completely or not to bother.

[The Natural Philosopher]

[Bill]

In message , Bill writes

Since writing this, I noticed that the current the ddPai M6+ camera was taking increased from the steady 0.5 amps to 0.8 amps, and the camera was getting fairly hot even on a cool evening.

I cracked the camera open and took the battery out. It looked slightly swollen.

The camera, back together, seems to work OK, although I know it won't save the last short recording if it loses power. It is cooler and down to 0.5 amps.

If anyone has one of these cameras I really recommend investing in a usb supply device that displays the current the camera is taking.