Author Topic: Lithium Protection Circuit  (Read 2648 times)

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Offline airman00Topic starter

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Lithium Protection Circuit
« on: September 07, 2008, 05:58:46 AM »
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?



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Offline Ro-Bot-X

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Re: Lithium Protection Circuit
« Reply #1 on: September 07, 2008, 06:27:34 AM »
The LIPoly batteries will blow up if discharged too much or overcharged. The role of the protection circuit is to prevent such problems.
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Offline airman00Topic starter

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Re: Lithium Protection Circuit
« Reply #2 on: September 07, 2008, 06:58:25 AM »
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?
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Offline Razor Concepts

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Re: Lithium Protection Circuit
« Reply #3 on: September 07, 2008, 09:47:47 AM »
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.

Offline bldavis

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Re: Lithium Protection Circuit
« Reply #4 on: September 08, 2008, 05:32:28 PM »
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,  :o

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Offline TrickyNekro

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Re: Lithium Protection Circuit
« Reply #5 on: September 09, 2008, 09:47:39 AM »
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
For whom the interrupts toll...

Offline Admin

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Re: Lithium Protection Circuit
« Reply #6 on: September 15, 2008, 03:53:49 PM »
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

 


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