Good point Chris, H

 

Ok- I can handle the small battery with a smart trickle charger and I have a gas additive. For summer my wife will live in NC so she will be driving it. And if we still cannot sell our house it sounds like winter is the best time to store a NiMH for low discharge rate.

Thanks everyone

 

Well I went down to my home in NC (living in MD until I can sell) and took the Civic for a ride. The SOC was full up just like I left it 30 days before. I drove it about a mile until I got it on a main road. I had almost all bars at that point With about 3 bars of assist to get up with traffic the SOC plunged down to 1 bar. It took me about three miles of coasting/gliding to bring the charge up to half.

Seems to me that the batteries do self discharge a significant amount in 30 days but at first glance you would not think so. I gave my key to a neighbor to drive it every month if I cannot get down in time.

 

Mark T. That was a recalibration only. Happens all the time , but we normally don't even see it or feel it. I guess you where watching it like a hawk! You could pick up a motorcycle 1 or 2 amp charger that will keep your traction battery at a safe level. H

 

I may be wrong but I thought you need a different type of trickle charger for NiMH batteries then for lead/acid. I believe the rate of charge and the SOC requirements are different--but I do not know battery chemistry.

If you are correct then what connector ends do you expose to clamp onto--do they mark positive on the orange cable.

 

Sorry Mark. I took traction to mean engine battery.Hal

 

What's going on behind the scenes is that your SOC doesn't actually know how much juice is in the battery--it calculates it based on previous usage. Since you left the car with a full battery, it though you had a full battery when you started out again, however you slowly lost some charge while you were gone. Once you were out on the road, your battery management system figured out that the actual state of charge was lower than it thought so it did a recalibration.

I have this problem almost daily in the summer, although I drive the car every day. In my case, (my opinion here) my HCH seems to think that it's banking more electricity than it actually is, and then it has an "oh crap moment" and recalibrates. I've had it looked at multiple times by the dealership, however since they don't find any codes, there isn't anything they can (or at least are willing) to do.

My problems are most likely due to the hilly commute I drive based on the fact that there are others in hilly parts of CO and PA that have similar problems. It seems to be more of a problem on the '06s than later models too. Of course, this doesn't help your situation with storing your car, but I thought I would post up clarifying how the battery controller actually DOESN'T know the SOC--instead it tries to calculate it somehow.

 

Yes, NiMH do self-discharge quite a bit in just a month. Giving the keys to your neighbor for a monthly run around the town is a good idea
::cringe:: Please don't do this. NiMH batteries do not charge the same way as VRLA ("maintenance-free" car battery).