06 Hybrid: left some interior lights on, battery drained: Which one?

I would think the small battery is the one that tied to the gas engine and lights. The charger has been on long enough to put enough charge to turn over the engine. Pull the charger off and try it. Automotive batteries do not like to be run down and are damaged by deep cycling them. You may get away with it but it shortens it's life. If it works keep an eye on it and take it to a parts store and have them load test it.

No.

I am confused, the gas engine in my 2007 does not "crank" it is brought to life by the electric motor, exactly the same way it is reactivated after a stop, I presumed the small battery was for lights & such, maybe if it is too dead, it won't sustain the electrical need not supplied by the hybrid batteries.....it would be interesting to find out what happens, let me know won't you.

I was wondering the same thing: I too think the electric motor is instrumental in cranking at start up, simliar to recovery from auto- stop.

Anyway, disconnected the charger, gave it a try: it started ok, and took it for a drive. For the first few block the IMA battery state of charge indicator was totally blank. Now this could be due to the battery drain wiping the memory, we've had similar when the computer was updated. Also, the engine sounded a little funny, not sure if it was my imagination ;)

Normally with a cold engine the charging indicator (green bars) doesn't happen, until the engine has warmed up a bit. But in this case it seems to come on almost immediately. And regardless of acceleration state, It was always showing 3~4 bars (out of around 10) charging. Took it up a steep drive, with the transmission in in sport, it charged going *up* the hill, which seems unusual. Coming back down the IMA battery state got to fully charge, so much so that the motor "braking" shut off, and the braking was purely by the brakes themselves.

Got home, the small regular battery is still showing discharged on the indicator. I've gone through this before, and I believe it got back to showing full charge after a few days driving. Still, as one responder noted, I think we've used up one of it's lives. Hopefully it's got a few left. It's in for oil change on Tuesday coming up, I''ll bring it to their attention and get it checked.

Thanks all!

I can't speak definitively for the Civic Hybrid, but on my Insight, the

That makes perfect sense, Mendel indicated that the computer was acting odd (and it is not even windows) after he recharged the battery....one of those things you just don't think about.