Safe recharging of lights overnight

[classic33]

If the lid is on tight there won't be a decent supply of oxygen to support combustion ( unless you have made a big hole to put the wires through ).

Triangle of fire .

Batteries may get warm enough to start burning the material the tin is left on. Not a very good heatsink really.

 

[Tin Pot]

Yes.
A USB port offers charging voltage of up to 5v and can give 500 mA output max so provides 5v x 0.5 amps = 2.5w
I use a front light with a separate battery (lithium ion), the charger for which offers 8.4v and 1 amp - the battery is 8.4v nominal (4 x 18650 batteries in series parallel) and rated as 4400mAh.
The batteries you can charge using a USB are quite small (ie low capacity and voltage). Not sure whether that makes them less or more likely to catch fire but the power going into them is much less.

I agree with this ^^^^^. My batteries are from Magicshine.
From Battery University: "Lithium-ion operates safely within the designated operating voltages; however, the battery becomes unstable if inadvertently charged to a higher than specified voltage. Prolonged charging above 4.30V on a Li-ion designed for 4.20V/cell will plate metallic lithium on the anode. The cathode material becomes an oxidizing agent, loses stability and produces carbon dioxide (CO2). The cell pressure rises and if the charge is allowed to continue, the current interrupt device (CID) responsible for cell safety disconnects at 1,000–1,380kPa (145–200psi). Should the pressure rise further, the safety membrane on some Li-ion bursts open at about 3,450kPa (500psi) and the cell might eventually vent with flame. (See BU-304b: Making Lithium-ion Safe.) Venting with flame is connected with elevated temperature. A fully charged battery has a lower thermal runaway temperature and will vent sooner than one that is partially charged."

I place mine under the pillow when charging overnight.

That way, should they explode, my head will be vapourised instantaneously and I'll be none the wiser.

 

[albion]

I used to work in the hobby trade and I’ve seen many catch fire. Problems can occur when they are run down to nothing. If you notice any swelling throw it away. I’d. never charge them in the house. Outside socket is the way to go.

Problem with tech likes phones and a few lights is anorexia, causing batteries to need a full charge. Charging after every ride helps.

Once a lithium is charged, there is no charge current so I do not have any problem here.

 

[classic33]

Problem with tech likes phones and a few lights is anorexia, causing batteries to need a full charge. Charging after every ride helps.

Once a lithium is charged, there is no charge current so I do not have any problem here.

Unlike those mentioned by @Cycleops, phone and light batteries tend to be hidden where you can't the cells themselves. So early indications will be missed.

 

[Blue Hills]

Problem with tech likes phones and a few lights is anorexia, causing batteries to need a full charge. Charging after every ride helps.

Once a lithium is charged, there is no charge current so I do not have any problem here.

And is it true that with nimh batteries you can do this endlessly with no need to perioidically do a full discharge to preserve battery health?

 

[Ajax Bay]

is it true that with nimh batteries you can do this [charging after every ride] endlessly

http://batteryuniversity.com/learn/article/nickel_based_batteries

 

[Blue Hills]

Many thanks for that. Very educational, and even, who would have thunk it, some laughs. In the discussion of lithium ion i loved the battery industry's spectacular talent for euphemism:

The temperature can quickly reach 500C (932F), at which point the cell catches fire or it explodes. This thermal runaway that occurs is known as “venting with flame.” “Rapid disassembly” is the preferred term by the battery industry.

 

[albion]

You can make safe by simply using a lithium iron phosphate battery instead.
The lack of consumer friendly regulations is a big risk.

I do not have a clue which type is used in my bike lights. Hopefully they are the phosphate ones, which last 1000 + deep cycled. Standard lithium are lucky to make 50 cycles if fully discharged every time.

 

[classic33]

Many thanks for that. Very educational, and even, who would have thunk it, some laughs. In the discussion of lithium ion i loved the battery industry's spectacular talent for euphemism:

The temperature can quickly reach 500C (932F), at which point the cell catches fire or it explodes. This thermal runaway that occurs is known as “venting with flame.” “Rapid disassembly” is the preferred term by the battery industry.

All the joints/connection between individual cells are broken and the outer casing may melt.

 

[Ajax Bay]

the phosphate ones, which last 1000 + deep cycled. Standard lithium are lucky to make 50 cycles if fully discharged every time.

What do you mean by 'standard lithium' (?LiCoO2?) and where do you get such a low life figure for full discharge/charge?
http://batteryuniversity.com/learn/article/types_of_lithium_ion

 

[albion]

I guess it is now the opposite, you being unlucky getting 60 charge cycles.
Tests show randomness between cells and gone are the days when burning hot laptop designs fried the cells to death.

 

[albion]

https://www.itri.org.tw/eng/DM/PublicationsPeriods/745621425201177074/content/focus2.html
https://www.eetimes.com/author.asp?section_id=36&doc_id=1332583

This supposed 'quick fix' apparantly negates most of the fire risk whilst enhancing most things for normal lithium batteries.
An increase of 10% in productions costs mean manufacturers may not be that keen, unless we get safety regulation or they become liable for putting our safety at risk.

 

[hoopdriver]

Look at the Apple and Samsung phones that have gone pop, yet no one gives a second thought to charging their hypno-phones while they sleep

I have all Apple stuff - iPads, phone, laptops, - and I know the quality is great, but I never leave things on charge over night. I have a Lupine headlamp and they also has a very fine reputation, but once again, I do not leave them on overnight charge. I just find a way to charge things during the day when I am around.

 

[SuperHans123]

Some people on this thread definitely missed their calling in life as Risk Management experts.

 

[Blue Hills]

Some people on this thread definitely missed their calling in life as Risk Management experts.

Yes i am a cautious sort but have no problem leaving my tabs or AA/AAA battery chargers charging overnight or when i am out. Often a must with the latter as i use a slow charge to prolong battery life. Just use reputable products, obviously take notice of press stories with regard to particular product issues. And don't try to be clever saving a few pennies by getting lights and chargers from funny foreign sources.