Hello! I hope you are doing very well. I have a 2008 FA3 Civic Hybrid, pre-facelift model, currently at about 227.xxx kilometers (141,000 mi app.), and I am experiencing very frequent battery recalibrations (events when the SoC of the battery drops very fast, from 7 bars to 2 or 1 bars), specially when using the A/C. As I am from Chile, my car has not been recalled to install the famous software update that supposedly cuts fuel mileage – it only had a recall to change the Takata passenger airbag. I have noticed that this events happen most when I am in a stop with auto stop engaged and the A/C on, and also when I climb small steep hills at low speeds (when the ICE gets heavy assist from the electric motor). Finally, the battery was changed in June 2023, and it is covered under warranty until June 2025.
With all, is there any solutions for this events, or they are considered to be normal? Is the SoC gauge displaying real time information about the battery charge? Should I try to disconnect the 12V battery to "reset" the system?

Your help is very appreciated. Thank you!

 

This condition is not normal. It is a sign of imbalanced cells. It sounds like your car was patched to include the update as frequent recals are a symptom, i.e., it will recal rather than throw a P0A7F code.

Recommend you continue driving it aggressively hoping to trigger a code prior to the warranty expiration.

Alternatively, document the behavior via video and try to force them to replace it as the car's performance and mileage are clearly suffering.

 

Thank you very much for your help, I have seen that recals happen because of imbalanced cells. This means that the normal behavior should be the SoC displaying “real time” information, i.e., when auto stopped and using the A/C (heavy electrical load) the bars should decrease slowly and not abruptly to 2-1 once the ICE restarts?
I am going to record the events and communicate with the guys that changed the battery, following your recommendation. And yes, with highway driving I am getting around 20-23km/L (~ 47-53 mpg), however, in the city I always get 13.5km/L (~ 31 mpg), even when I drive with the A/C off, without much elevation change and always trying to drive efficiently.
Finally, in case they refuse to install a new battery, is there an “easy” -and safe- way to prevent the system from recalibrating itself? Like, recalibrate it yourself by disconnecting the 12V battery?

Thanks again for sharing your knowledge!

 

A clear indication of a recal is a steady "march" of the gauge at a rate of 1 bar per second. DOWN to 1-2 bars is a negative recal. UP to full is a positive recal. A recal occurs when:

1) One of the 11 tap voltages triggers full while the others lag.
2) One of the 11 tap voltages triggers empty while the others lag.

An occasional recal isn't an issue, and it usually only occurs at one end - either a positive OR a negative recal. BOTH are an indication of severely imbalanced cells with reduced capacity. Comparatively bad city mpg is another symptom of a failing battery.

I recommend you abandon all efforts to get good gas mileage. Drive the car aggressively, use the A/C if there's even a slight need, etc. The goal is to stress the IMA battery to the point that it throws a failure code.

DO NOT UNPLUG YOUR 12V.

While I have recommended that in the past, it typically only helps for a marginally imbalanced battery, and it only makes a small improvement. There is no way to significantly improve the performance of the battery without a grid charge and discharge. This should only be done when there is no warranty remaining.

 

Thank you very much for your help, S Keith, I am going to follow your recomendations. If anything happens, I am going to inform it in the thread.