What I want to know is: Has anyone tried this? (Jump starting the 12 v battery from the 300 v battery by pressing that button and waiting 8 minutes. ) If it works I would rather do that than call the tow truck guy. I go to off road areas and it is tricky for tow guys to go there.

Have you done this? Leave the key in on position and let the 300v batt charge the 12v batt? I would not be able to jump my 12 v out in the boonies.

I would not be able to plug in a small battery charger out in the sticks. I barely get cell phone service in Maha`ulepu.

The 12v battery would be in worse shape after several months (especially with residual electronics operating) so you'll still be SOL if you do that. I'm pretty sure they tell you in the manual that you have to run it every so often so that it doesn't happen.

Also, there really isn't enough energy in the 12v battery to put much charge on the HV battery. It would be like trying to charge a 12v car battery with a D cell flashlight battery, yes it will charge, but not enough to make a difference.

I doubt Ford was trying to make it impervious to any and all situations, rather just trying to make the more common situation less of an annoyance.
see http://www.greenhybrid.com/discuss/i...down.2833.html

If your 12v battery is dead, putting the key in the "on" position will do nothing because there's no 12v power available to energize the HV relay and the DC-DC converter. The high voltage cannot pass through the ignition switch, that would be totally unsafe, so a 12v relay is used to cut the HV battery off from the rest of the system when the vehicle is off. Bottom line is that you need some 12v to start the process of charging the battery, and that's what the jumpstart button is supposed to do.

If you still have a little bit of power left in the 12v battery, then yes it might work, but maybe not, depending on just how dead it is.

2001 Prius Photos       2005 Prius Photos
'97 Prius Simulation Prius inner workings

I'm afraid I have led us all down a garden path. My dealer directed me to page 237 of my manual, where it actually was talking about jump starting the big pac. He then led me through the instructions and I got that he was talking about charging the small battery from the big one. WRONG!! He may not have understood my question and so directed me there. I didn't read it thoroughly for myself until last night and realize we were talking about two different things. If my 12v dies again I guess I will have to call a tow truck or depend on someone else meandering out in the boonies. I'm a little leery about having just anyone jump start my vehicle.

If you are really concerned about the 12v croaking in the middle of nowhere, the best insurance you can have is one of those booster packs, they are relatively cheap (this one is $50 CAD) and very effective. You can also run things from them so you don't have to drain the car's battery too.

2001 Prius Photos       2005 Prius Photos
'97 Prius Simulation Prius inner workings

I was just about to suggest the same. They are also available with air compressors included, so you can even deal with a low tire.

This one's got it all! 150W 120vAC plug, 12vDC plug, air compressor, flashlight...

Very handy, even around the house.

2001 Prius Photos       2005 Prius Photos
'97 Prius Simulation Prius inner workings