Two weeks ago, my husband and I drove about 90 minutes to a nearby mountain for some snowshoeing. Everything with the car was fine, until we stopped (for about 5 minutes), after which the car BARELY started. When it was time to go home, the same thing happen, and the battery light was on (not the hybrid battery, but just the regular battery). Since the car was running, mostly, and it was Saturday afternoon, we decided to try to make it home. Since the battery wasn’t charging, one by one, all the electrical systems shut down, starting with the wipers and ending with the fuel pump. We drifted to a stop on the side of the road.
AAA came and jumped us, which not only got us going but seemed to have solved the problem. The battery tested fine, and Honda ran tests on the car for 3 hours and couldn’t find anything wrong. However, we’re clearly nervous about taking the car out of town.
There was a similar incident a couple months ago, but not nearly as severe - the batter started charging again on it’s own after just a couple minutes.
The Civic hybrid does not have an alternator, the IMA motor provides generator duties through the hybrid system.
Was the check engine light on as well as the battery light?
Were you getting IMA assist when the battery light was on?
I believe you had an electronic fault and the IMA was not charging the 12 volt battery and was probably not providing 12 volts to run the 12 volt systems in the car. Once you ran the 12 volt battery all the way down it was similar to unhooking the battery cables and the computer was reset. Once the computer reset then things were as normal.
I had a similar instance with my G1 Insight once but I don’t remember what the cause was. I can tell you that my hybrid battery was on the way out at the time.
If this happens again you can probably resolve the issue short term by disconnecting the negative battery cable on the 12 volt battery, but you may want to have this looked at by a professional to at least see if any trouble codes are present.