Once every couple months or so I check my HV traction battery cell balance with My Volt Control Diag and/or MyGreenVolt Connect OBD apps. To my knowledge, in an ideal world (that doesn't exist) all cells would be within +/-5 millivolts (10mv delta) after a full battery charge. A year ago I was seeing 10-15 cells just outside of the ideal range. All cells appeared to be functioning properly - no big deal. In August 2022 my Battery Energy Control Module failed and was replaced in November. Since then I’ve seen roughly 40-50 cells register outside of the ideal range with a voltage delta around 25mv. My hunch is that this change may have to do with (1) how the new BECM was calibrated to the car during install or (2) the fact that the car was stored, mostly in a garage with <50% HV battery charge and the 12V battery disconnected, for about 4 months awaiting the new part.
“Ideal” specifications aside, my question is what is reasonably “normal” for a now 5 year old battery with 39K miles, and does a starting cell balance delta in the range of 25 millivolts really matter? 25mv doesn't seem like big spread and as far as I can tell all the cells are functioning okay at this time.
“Ideal” specifications aside, my question is what is reasonably “normal” for a now 5 year old battery with 39K miles, and does a starting cell balance delta in the range of 25 millivolts really matter? 25mv doesn't seem like big spread and as far as I can tell all the cells are functioning okay at this time.
