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Would a fuel gauge IC that also monitors voltage and temperature be enough for monitoring a NiMH battery during charging and discharging? Charging ICs monitor just voltage and temperature so I think using a fuel gauge IC that sends data to the main IC in my design, so a switch can be operated, to turn off the battery charge/discharge would be sufficient. Is there something I am missing here that would disprove this?

Edit: Both monitor current as well.

Davide Andrea
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Matthew3302
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  • "Charging ICs monitor just voltage and temperature" - no, they monitor current as well. – Finbarr Jul 05 '23 at 21:44
  • This is too vague to be answerable. You're asking if a coulomb counter (fuel gauge) is "enough" to monitor a battery during charging/discharge. What is controlling the charge itself? Is it constant current/constant voltage capable? What battery chemistry is involved? Battery charging is not (depending on chemistry) just an on/off throw of a switch based on monitoring data. – JYelton Jul 05 '23 at 22:52

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A fuel gauge IC works in conjunction with an all-in-one BMS IC. It's that second IC that monitor voltage, current, and temperature, not the fuel gauge IC. The fuel gauge IC is only there to do the data manipulation, not the analog interface to the cells.

So:

  • The direct answer to your question is: no. A fuel gauge IC by itself doesn't monitor anything.
  • The indirect answer is: yes. The complete BMS (two ICs, BMS + fuel gauge) does monitor and, most importantly, protect the cells.

so a switch can be operated, to turn off the battery charge/discharge

Do not do that: it's risky. Instead, let the BMS IC operate the protector MOSFETs directly, as it was intended. Anything else you may rig-up is bound to reduce reliability. And that's a risk of fire. Not worth it. Use the Li-ion BMS ICs as they were intended to be used.

Davide Andrea
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