Balancing battery packs with a stamp
petri
Posts: 5
·Hi all, 1st post here. I know a little about electronics and I'm looking to learn more in the near future. This is an offshoot of another hobby, radio controlled airplanes and helicopters. I've come across the need for a Cell balancer that will balance 14 cells in a battery pack. They are A123 M1 cells with a max voltage of 3.6V. From the little bit of reading I've done I see I'm going to need an ADC to read voltage and communicate it to the basic stamp2. I was looking at a MAX1258, has 16 channels and runs on 5V. The balancer would need to read voltage of each cell and then store it as a variable. Program logic would then need to Discharge any cell over 3.6V thru a transistor and resistor at hopefully 2A. After all cells were equal to or less than 3.6V it would then need to read voltage of each cell and discharge each cell that is higher than the lowest cell to bring the pack into balance. Anyone have any thoughts on this whole idea or maybe working on something similar? Thanks Rob D.
Comments
You might want to look at this as well
http://www.intersil.com/data/an/an1333.pdf
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Sam
-Phil
-Phil
The output from the multiplexer will feed your voltage divider, thence to the ADC. Since the multiplexer has an enable input, you can turn it off, thus disconnecting the voltage divider from all of the cells to save current drain.
This may well be the simplest practical setup. With two multiplexers, you would need only a 9-bit ADC, but sequencing the multiplexers to avoid over-voltage and negative-voltage situations could get a little tricky.
'Hope this helps...
-Phil
http://www.astroflight.com/store/store-type-tem.html?item=products:af-106-123&sid=0001o71rHpVhXhEXWY5f8L9
I have two of these now and you can chain them together but they only have about 130ma current dissipation per cell. I was thinking I'd just upscale the whole thing for the higher current and aditional cells. It uses a PIC chip to run the whole thing. I sent the manufacturer an email requesting what I'm looking for, maybe I'm not alone...... I'm not sure how astro is doing it, but it looks easy when done with SMT parts [noparse]:)[/noparse] I'll have to reverse engineer it and see if I can learn something... Thanks again for the help!
on-chip A-D converters 6 channels and 12 bits.....
Thank You for posting this Link
www.astroflight.com/store/store-type-tem.html?item=products:af-106-123&sid=0001o71rHpVhXhEXWY5f8L9
They have some cool stuff
I'll have to reverse engineer it and see if I can learn something...
Please let me know what you come with if you do not mind
Thanks
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··Thanks for any··that you may have and all of your time finding them
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Sam
Post Edited (sam_sam_sam) : 2/29/2008 5:14:32 PM GMT