North Australian FISH FINDER TM forums

I bought some cheap LED torches with rechargeable 18650 batteries.

Crazy good lights for the price, it seems.

But then I read that the 18650 batteries are dangerous without a circuit protector.

Since my kids use these, I am concerned. Anyone had/heard real evidence of trouble?

Might charge them outside the house, and buy some AAA torches for the kids.

I found one example of an exploded torch on the net, but it had eight of these 18650 batteries in it, my torches use only one.

18650 batteries are one of the most reliable and safe forms of lithium-ion batteries around. This is the type of battery in all of your cordless power tools and most laptops with removable batteries. Circuit breaker protection or balancing protection of batteries is only really needed if you have multiple cells (batteries) provided that you don't short out a cell.
The main risk comes from multiple cells if they are shorted together. Or if the voltage between cells varies greatly as they will level out the charge between them. In reality, unless you have a lot of batteries in an array the actual current draw isn't all that great and the primary risk is when the array is first built if the batteries are not within say, 0.25 volts of each other. Then there is a "need" a battery management system but again there are many examples of manually balanced batteries being put together and staying balanced with each other a long period of time, simply because they are wired in parallel.
What's important is that you don't exceed the maximum charging voltage of any cells. I forget the number but I think in the order of 4.2V. Chargers for these batteries should have a high and low voltage cutoff that protects the cells. This is either built into the charger or by a battery management system attached to the battery in the device. If it doesn't have one of these, then yes, it is potentially dangerous.
If you're that way inclined you can get these cheaply online (like $10 for 5) and jerry rig something up or spend $100 and get a proper lithium-ion charger that has the overcharge protection built in.
Disclaimer..... I am no expert and you will probably burn your house down if you let the kids charge them inside the house.
Dan

Been using these for about 6 years and have 4 single battery and three double battery torches. No issues. When the battery dies they won't charge. So i get out another spare from the 10 spares i bout for $15. Always check or use items with batteries if they dit flat for too long they could leak and ruin the item or something worse if your very unlucky. Love my ultra beight cree torches. Makes the dolphin look very dull but don't last as long and can't swim.

Joe

Thanks for the replies. I did notice one got surprisingly hot while in use, but I didn't think much of it as I hadn't read the warnings.

Will put the kids on AAA units just in case, and charge the others out in the shed.

Separately, I had a cheap 240v LED light bulb explode in the ceiling mount and catch fire, gotta wonder whether these cheap bulbs are worth it, but I have not heard of houses burning from bad LED bulbs, I did an online search.

Matt, some of these cree torches have a AAA battery adapter so you can change the battery type. Love the Varta batteries from bunning as great value.

Joe

18650's are good. Just buy quality, (LG, panasonic, sony) the rest are pretty well factory seconds. The main thing you have to understand is that the whole case, including the positive end's shoulder is negative. So any nicks or cuts in the heat shrink can lead to a catastrophic short circuit. I've no doubt all the pics of people burned from exploding e-cigarettes are from damaged heatshrink covers on 18650's. New heatshrink covers can be had for as little as 20 for $1 and be applied by a hairdrier. Twin 18650 battery transport cases are $1 each too, well worth it. A quality charger is the next investment. I run a nitecore, but efest and luc do a good one that wont over, or under charge the batteries.. 18650's dont like to be discharged below 3.5v either so change and charge regularly, and dont store them in the device for very long. Knowing all this makes them very safe, long lasting and reliable.

Cheers. Good advice. But a bit of mucking around involved. I've got a Chinese charger and batteries ... no explosions yet tho ...