# 3 cell lipo battery gauge IC

I need to monitor individual cells (3.7v) of high capacity 3-S LiPo battery and couldn't find IC that can do that.
MAX17043 seems like a great chip and already has Arduino library but it can only do 2 cells. I think I can just use too of them on same PCB, or do you think it wouldn't work?

I don't think it's possible to daisy chain these. Maybe estimating the charging state by measuring the voltage is good enough?

lg, couka

couka:
I don't think it's possible to daisy chain these. Maybe estimating the charging state by measuring the voltage is good enough?

lg, couka

Why not? Library limitation?
Yeah if I can't find suitable fuel-gauge IC, I'd probably have to use AVR to do voltage measurements...

Electrical limitation. Because the negative of cell 2 is also the positive of cell 1, when you connect cell 1's to the power supply negative... everything will be fine. But then you also need to be able to connect cell 2's negative to the power supply negative, and cell 3's negative to the power supply negative (as the negative of the battery and the power supply at intended to be commoned together with this IC, because it only expects to be used in a one cell system. It's bigger bother, the MAX17044, can measure 2 cells, but cheats by just measuring both cells together, so you don't get individual cell readings. I also wanted to do the same as you, and instead just used a resistor network and calibrated the readings to measure the overall pack voltage. But there is nothing stopping you from measuring the cells individually if you have three analog channels free and using the correct voltage divider configuration for each cell.

Hi,

@pfeerick

But there is nothing stopping you from measuring the cells individually if you have three analog channels free and using the correct voltage divider configuration for each cell.

The problem there is loss of resolution.
But you did hit on an idea.

Use the MAX17043 to do the bottom two cells in the stack, then with arduino analog, measure the total battery pack.
Then subtract the sum of the lower two cells from the pack total, and that will give you the third cell potential.

Just a thought.... Tom...