I have just asked a manager in the fire service whether there has been a plague of lithium battery fires.
His answer was not really. The main problems they have seen, in the early days, were people leaving them on charge for long periods.
More recently, especially with Covid the fires have not tended to be the fault of the battery really but that fact that people put laptops and things on cushions and leaving them there or in particular people who put mobile phones under their pillows.
Peter wrote:
I have a LIPO fire bag within reach too.
Where do you get such bags? I looked at a few pilot supplies webshops without finding anything.
Airborne_Again wrote:
Where do you get such bags? I looked at a few pilot supplies webshops without finding anything.
ebay is full of them:
https://www.ebay.de/b/Lipo-Safe-Bag/bn_7005706222
I should make an “aviation version” for 80 Euro ;-)
One good thing to do about charging is to keep battery level > 80%, to ensure charging current stays below max current. At max current, you have a lot of heat generated. With lithium battery, when charging from low battery level, it goes up to max current until the resulting voltage at battery level reached 4.2V per cell, then current decrease to not over-volt it.
If you wait for your device is at 20% when you recharge it, it may just help to overheat it.
Airborne_Again wrote:
Where do you get such bags? I looked at a few pilot supplies webshops without finding anything.
You can find it in RC shops.
https://hobbyking.com/en_us/fire-retardant-lipo-battery-bag-230×140mm.html?___store=en_us
Name one phone and one tablet where you can force the battery charge to stop at 80%.
Having written that, I guess I’ve seen an iPhone say it “stopped charging but will top up the battery before the usual charger disconnect time comes”. But am not sure if one can say “just stop at 80%”.
Just charge it fully before fly, and connect charger while in the air.
That’s exactly what I do. Start with everything fully charged, and then in-flight charging doesn’t generate much heat.
However what also generates heat, more than anything else, is the screen brightness setting. Then we move to the discussion of tablets shutting down in flight – elsewhere 
tmo wrote:
Name one phone and one tablet where you can force the battery charge to stop at 80%.
The other way around. It is (according to greg_mp) charging below 80% that is dangerous as the charging current is higher. So you should make sure all devices are already charged to no less than 80% before charging them in the aircraft.
