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Author Topic: Lithium Protection Circuit  (Read 1936 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...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

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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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