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Shunt Equalizer Test.
DamonHD:
Yes, me also.
Rgds
Damon
waitatian:
It works by amplifying any difference between the battery center connection and 1/2 the volts of the two batteries.
I tried a few different input configurations for the op-amp. The damped comparator? was the first one that worked. The op-amp was chosen because of its shutdown terminal. The 500 ohm trimpot sets the voltage that it will start equalizing.
The 2 ohm dump resistors add a bit to the price, which a microcontroller system could get rid of. Six 5W resistors were cheaper than 10W or more resistors, and cutting down maximum current would lessen the resistor price.
The BDX34/35 transistors are darlingtons. The other transistors are whatever is laying around, but the two by the 500 ohm pot should be the same.
The led board will show if there is a big fault like a shorted output transistor, but it won't show a bit of leakage.
SparWeb:
Thank you!
For once I look at a schematic and realize "I have most of that stuff".
Except of course for the TLV op amp, this is done with very pedestrian parts.
The TLV isn't a stocked item at Digikey, but they do have a few left - I'd better order soon!
waitatian:
I don't like circuits with unobtainable or expensive parts either.
I got most of the parts from Digikey. They didn't show the op-amp as endangered when I got them. It was chosen because it was the cheapest one with a shutdown pin.
If it is discontinued, the output power of the replacement would need checking and the value of the 560 ohm output resistor increased if needed.
If you build one, it is advisable to have covers over the ends of the leads when installing it in case one of them ends up where it shouldn't.
SparWeb:
My battery stack actually has a strong cell beside each of the bad ones. Which gets me thinking...
Would it make sense to you if I made only 1 shunt equalizer, and put it on only 2 adjacent batteries?
I see you have put your equalizer across all of the cells in your battery stack, so do you have any warnings about putting an equalizer on just 2?
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