Lithium Protection Circuit

[airman00]

Hi,

I am planning to use Lithium batteries on one of my projects and was wondering if I really need a protection circuit. I mean if I were to only have it running for like 1.5 hours and the circuit is short circuit proof(dipped in plastic), would it still be necessary?

[Ro-Bot-X]

The LIPoly batteries will blow up if discharged too much or overcharged. The role of the protection circuit is to prevent such problems.

[airman00]

The LIPoly batteries will blow up if discharged too much or overcharged. The role of the protection circuit is to prevent such problems.

but if I know they will not be discharged too high and I have a smart charger , then I don't really need one?

[Razor Concepts]

Lithiums dont blow up if you discharge them too much. They will if you discharge them faster than their C rate, but if you get its volts down too low it'll die quietly without a big fireball or anything.

[bldavis]

I run lipo's in most of my planes and a Heli, i don't think the problem comes from the discharge rate (unless higher than the C rating) but I would much rather be safe than sorry, lipos will puff if used incorrectly and that will result in a fire ball if charged too quickly or allowed to overheat; weather it be by charging or discharging, or simply leaving them in a place where they get to hot i.e. the car. it is not a fun experience to distroy such a pricey battery. But, back to the point i think that the safty that a protection circuit will provide far exceeds the time or money that you will save. I think that a protect circuit should be used. But then again i am the guy building a guided rocket, ROFL, 

- have a great day and be safe (for yourself and those around you devices) still ROFL 

[TrickyNekro]

Back in topic...

Dallas Semi offers some very good Li - ion / Li Po protectors... It's all about an IC... and some external but they are worthless...
Now the bad thing is that HELL they don't offer samples for their protectors... DARN, I wanted some... That's unfair....
Anyways...

I think TI has some protectors as well... Go there and see what you can fetch... they offer samples as well...

Good hunting,

Lefteris

[Admin]

Lithium's need a protection circuit, no way around it.

Discharging too much would damage the batteries. Charging too fast would start a fire or at best overheating damage.

If you have cells in parallel, you could get uneven charging, resulting in self-discharging.

Check these:
http://www.dimensionengineering.com/CellShield.htm
http://www.dimensionengineering.com/VHVBEC.htm