Hello, I'm running into a bit of a strange problem when measuring battery voltages with the terminal boards for the TC-08 (using the 5V connection, with the switch off so it isn't measuring current). I'm attempting to use them to monitor each cell of a 2 cell battery pack, with one board measuring cell 1 voltages, and the other measuring cell 2. The cells are connected in series so the first board is connected to the cathode of cell 1, and the anode of cell 1/cathode of cell 2. The second board is connected to the anode of cell 1/cathode of cell 2 and the anode of cell 2. I also have a 3rd terminal board that is connected to measure voltage over a sense resistor connected in series with the battery.
The problem arises in the second terminal board, measuring the voltage of the cell 2 battery. It always has some kind of offset from what the other board is showing (which always shows the correct voltage), which makes it seem like the cells are unbalanced. If I check the boards with a DMM I can see that the cells are very balanced, only off by something like 1 or 2 mV, whereas the offset can be up to almost 400mV. This offset varies directly with the battery voltage, being largest at full charge.
I'm not exactly sure what's going on here. Maybe I'm missing something about this setup? Or are the terminal boards connected in the picologger somehow? I feel like it's either something about the terminal boards I'm not understanding, or something about the general setup that is being completely lost on me.
Thanks for any help!
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