Thanks for the info Anton, very interesting. I don't know why this would happen, unless they are worried that you would run the battery down so low that an engine start would be impossible later. Perhaps the thinking is "Eventually they will put this thing in drive or park, and we will already be running ready to charge?"

It gets late early out there. - Yogi

It surprised me. It was about 112 degrees that day with the car sitting outside all afternoon, so I'm sure the battery was very hot. I had the A/C auto set to 72 degrees. That had the fan running at 1 tick below max. Still, 4 minutes is fast to drain a 1/3 full battery.

Since most of the responses I got were conjecture or opinion, I called the dealership and spoke to one of their technicians. He said the HV light meant the battery was fully or almost fully drained, but that's not the whole story. The bottom of the battery meter usually means the battery is fully discharged, however, there is a temperature protection circuit that shuts off certain sections of the battery if they are too hot. He said it's likely I still had a charge remaining, but the system couldn't "see" it. Even using the battery to run the A/C might have heated it up and shut off some of the battery I initially had available.

Answering my question. Even with the HV battery drained, the 12v battery was not affected. Both batteries have to be drained for there to be issues with either starting or driving below 40mph.

I got a few tips from him as well (as he owns a 2008 NAH). He said that changing the oil is not really necessary until about every 6000 miles, maybe even more (he recommends the synthetic). He said it's probably best every 3000 just check the fluids, top them off as needed, and change the air filter (it's very dusty here in the desert). He said not to use any products that you pour into your tank like octane boosters or fuel system cleaners. It has something to do with corroding certain parts in the engine (I think that warning might already be in the manual).

I am not entirely sure what the logic behind the engine coming on while in N is... Perhaps its a scenario that was missed from the design of the system? Or maybe the idea was that there is no reason for the car to ever be in N while its on. If its stopped, it should be in P or D/R with foot on brake, and if its moving it should (legally in some places) be in either R or D. N doesn't really have any use (at least legally :-))). (well there is towing reasons, but then the car isn't on).

From mentioning R, I am wondering if the batteries charge while in R and if the gas engine hooks up to the drivetrain while in R? I have noticed that the reverse is fairly weak even if you stomp on the gas pedal. If parked on a steep hill and need to back up (up the hill) the NAH is just gutless and I usually end up exerting half a battery charge just to move 6 feet to pull out of a hilly parking spot.


To Stephen:
the 112 degrees could certainly be the culprit. Thats above the high-end cut off for the baterry.

If you look at http://eahart.com/prius/psd/
It appears that the ICE can never really do much work in reverse.

If you slide MG2 (in the model) into negative territory (reverse) the ICE never
is able to get into the green area without MG1 reaching it's limits.

It gets late early out there. - Yogi

Woow cool! Thanks for the link, I love the animations !