I've had some unusual behavior and wonder if any of you have had similar experiences. On a few occasions when the ignition has been in ACC mode and the stereo has been on for a couple hours or more the stereo cuts on and off (sometimes shuts off completely) and then the car fails to start. The last time this happened it would not start (or even turn over, acting like the battery was dead). Several attempts to start it over 30 minutes or so were unsuccessful. About an hour later, it started up fine and everything seemed normal, except the stereo would not work until the code was reentered.

Does anyone have an explanation for this? I'm not sure what the relationship between the lead battery (presumably used for starting) and the battery pack is. Is it possible that over time the battery pack is used to recharge the lead battery? If the lead battery is dead, does the battery pack kick in to start the engine?

Here is a post where we are missing MSantos...

I'll take a stab at it.

The 12 Volt battery that runs our accessories is fairly small by modern car standards and you drained it. The 12 Volt gets its charge from the traction battery through a DC-DC converter, which I assume is only on when the key is in the 'ON' position. It probably took a little while to get the 12 Volt back up to operating Voltage once you put it in 'ON.'

There is no traditional alternator in our cars. The traction electric motor generates all of the electricity used in the car. The engine is normally started via this motor and the traction battery.

There is also a 12 Volt starter in case the traction battery is drained or won't function due to temperature.

My guess is you drained the 12 Volt battery, and there was less juice in the battery than the threshold that allows the car to start. It took some time before the DC-DC converter charged up your 12 Volt battery enough to allow it to start.

'08 HCHII Silver (Arrived July 10th!)
'05 Honda Civic 7th Gen LX (Wife's DD)
'98 VW Jetta TDI

Yes as Paul said, you need a new battery? There is not alot of amp. hrs. in this little back up battery, so don't over do it. It my still be ok for charging! H

Is there a traditional starter as well? That seems a bit of an expensive fix....I have a different car but in the Escape Hybrid there are internal safety relays that connect the HV battery to the rest of the system. The 12V battery is used to close the relays when you start the car. Do you have similar relays and the reason for no start is the low 12V not being able to close the relays?

On the Escape the backup for a low HV battery isn't a traditional starter its a charging system where the HV battery can be charged up from the 12V battery by flipping a switch and waiting a few minutes.

There is a traditional starter hooked up to the 12 Volt battery, but most HCH drivers rarely, if ever, have heard it used.

I don't know anything about the relays that must be satisfied to start the HCH, but that sounds likely.

I wish that the 12 Volt could 'back charge' the traction batter in the HCH, that would allow for a sort of plug-in hybrid, or solar powered hybrid.

I have a 5 Watt solar panel on order to keep my 12 Volt battery charged and keep it from drawing so much from the traction battery.

'08 HCHII Silver (Arrived July 10th!)
'05 Honda Civic 7th Gen LX (Wife's DD)
'98 VW Jetta TDI

Case in point... I've had my car about 2.5 years, and the 12V starter has only been used *once* ('twas a chilly -16C morning).

Someday I might even beat that wascally kenny!

No whammies... no whammies... no whammies...

Get a "boom-box" or and IPod. That's better than draining your battery(ies) to listen to music for hours.

Don't be a slug! Use Assist! That's what it's for!

Great advice! I assume you don't have teenaged drivers?