thermal cut-off for Li-ion battery packs?

[jeffosborne]

I built a 10.8v 18650 battery pack to power the LED lights I use for photography. It has 3 switched battery outputs for the light heads that have a regulator, and one MOSFET regulated output for my lamps without regulators.

I used a protection PCB from Battery Junction, fused it anyway at 4 amps, and put a 168 degree thermal cut-off (TCO) inline with the battery pack. It is not a resettable unit, and will blow like a fuse when it gets hot.

Does anyone else use TCO's for battery packs? I know I could use a comparator IC and a thermistor to turn off current when hi-temp is reached, but I don't have room for all that here.

Jeff O.

 

[Tronic]

I have disassembled a lot of Li-ion battery packs of mobile computers, scanners and printers at work to find out why they failed.
A lot of them had a thermal fuse inline with the batteries.

 

[Illum]

thermal fuse is one thing, but thermal cutoff is the other. thermal fuses IIRC isn't resettable and is there primarily as a last resort circuit breaker for catastrophic meltdowns.

thermal cutoffs in primaries exist in PTC form, where the resistance of the material increases drastically when the cell temperature reaches the thermocline area out of the cell's design and recovers when the cell cools

I'm not sure, thats a good question :thumbsup: