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Author Topic: LiPo protection circuit  (Read 3531 times)

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Offline cosminprundTopic starter

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LiPo protection circuit
« on: January 19, 2009, 12:17:54 PM »
I've got an 2S LiPo pack that works very nice to power my 2-servos bot ($50-ish bot). I'd like to add an protection circuit so I don't discharge the pack to under 6V as apparently that would kill the cells. I know there are ready-made protection circuits that only cost a few $$, but can I make my own? Does anyone have a link to a schematic for such a circuit?

For me anything that's "special" needs to be ordered on line from outside the country, that means high shipping costs. I'm obviously not willing to pay $50 in shipping for a $2 part!

Thanks,
Cosmin Prund

Offline TrickyNekro

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Re: LiPo protection circuit
« Reply #1 on: January 19, 2009, 01:25:46 PM »
Well.... I'm making one for the contest here.... but I'll be late due to exams.... :-\
Basically all you need is two resistors.... and some math...
Google "voltage divider wiki" and read for an instance....
Then get some reading to the

Thing is that I'm building a batt accumulator, with current sensors, serial to microcontroller interface
and such.... So I'll be late... but what you'll be needing is only the 50$ and two resistor!!!
And a buzzer to warn you that the battery is ending!!! :P
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..

Cheers!

Offline cosminprundTopic starter

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Re: LiPo protection circuit
« Reply #2 on: January 19, 2009, 02:28:07 PM »
So I take 2 resistors, make a voltage divider and sample the resulting voltage using one of my MCU's ADC pins. This way I'm comparing an fixed percentage of the unregulated battery voltage to a known regulated voltage (the voltage reference for the ADC is the 5V output of the regulator).

Thanks TrickyNekro, that's smart and easy! I think I can even put some LED's to show the actual battery capacity :D

Offline airman00

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Link: http://curiousinventor.com/kits/roboduino

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Offline cosminprundTopic starter

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Re: LiPo protection circuit
« Reply #4 on: January 20, 2009, 01:05:44 AM »
Thanks airman00. That blog post seems to be from this month (January 2009) - has this been discussed on the forum and I've missed it?

 


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