rapid HV battery drain on startup hot days only

...yes I was going to say the other reason the SOC may be going down fast if they are running AC at max the SOC drops off pretty fast. The other day thought my batt was dying but I think it was just AC on too hard (66F set point).

 

For those of you who have not experienced this: When you start the car, the HV battery fan comes on at the highest setting, and SOC plummets: 7 bars down to 2 within a minute, regardless of S1, A/C etc. It will cause a sphincter reaction to your person and make you think that your battery is dead. It's not, but it has become a little bit weaker...

 

Yeah, not really related to the heat, but I agree. Personally I like to warm up for about 60 seconds before having to accelerate into a traffic stream or climb any decent hill. At home I only warm for about 35 to 40 seconds, because it takes me another 20 to 25 seconds to get out of my quiet street and down to the main road. Anyway I've found that I use no more fuel by letting it have a short warm up. The better fuel economy from having a good SOC in the first 5 minutes seems to make up for (sometimes more than make up for) whatever is lost due to warming up.

BTW. The warm weather can also play a factor in this case too. Heavy AC usage coupled with the relatively high demand for motive power in S1 can make this very noticeable.

 

Since the previous thread was from 8/11 and I revived to discuss the heat issue it seemed pretty clear you were talking to me. Well, not directly to me, but by addressing the common issue being discussed here inferring that the resolution has more to do with the owners driving skills etc. than a flaw or issue with the car.

 

The main reason I reacted negatively is because I think there has been enough documentation by some of us with this issue to move beyond it's the way the owner drives the car and on to why some cars have this problem. If everyone's Prius had this problem, then fine, I'll work on managing my cabin temp as well as I can. But, I have several neighbors and have talked to a couple other Prius owners here in Austin and non of them have this happen with their cars. I also believe that if this issue was more pervasive that there would be a lot more threads about it.

 

Yes, this is the experience.

 

Hi Asmodeus. Plenty of hot weather here in Australia so I sometimes get battery issues in summer as well. I still don't get your particular problem from just parking in the heat however. In my experience you've got to get the traction battery hot regenerating it to full and then park in the heat. I don't think this should happen to a pack in good condition from just parking in hot weather. If yours does then I think your battery pack must be fairly badly degraded.

He's a thread were I reported on exactly this issue: http://priuschat.com/forums/gen-ii-...d-8-bar-blues-well-actually-8-bar-greens.html

After that experience I try to avoid parking with 8 green bars on hot days. Heat is definitely the worst enemy of the battery packs.

 

Thanks. We'll pay close attention to SOC when we park in the sun. We'll try running the AC before shut down to discharge the battery too. When our first battery pack died it did this same thing, but would do it anytime, not just when it was hot. Not sure what to do if the root cause is a weak battery pack again.Anyone know if Gen 3 Prius does this too? I feel bad trading in and passing this issue on to the next owner, but this particular example of a Prius does't seem to be a keeper.

 

Pull out of the garage, car runs fine on the way to the destination. Come out, start up and the SOC drops and then drive home with the ICE running full bore trying to charge the battery and the car is nearly powerless. We get 45ish MPG in temperate weather, it drops to 36-38 when it starts to warm up here in the summer. At least half our trips are ok because we start from a garage, this would be even more miserable if the car sat out.