Fast Charging the NiMH battery - COOL TIP

It's technically called the Whoa Pedal.

 

:lol:

 

today at work I arrived early and just left the car in Ready and parked, reading the paper. When the temp of the ICE dropped to 60C the ICE started ( normal) so I checked the MG1 and 2 temps and MG1 was at 35C and MG2 was at 32C so put my foot on the brake and put it in D and noted 7 amps charge, stepped on the gas and took the rpm to 2450 and checked the charge rate and it went to 38 amps charged and I held it there for 50 seconds at which time MG1 had climbed to 45C and MG2 climbed to 38C in the span of less than a minute. On the way home I get a run up a 10% grade of 3/4 of a mile and at the bottom I was I was doing 21KMs per hour and at the top I was doing 87, at the bottom the MG1 temp was 32C and at the top it was 38C MG2 was 36C and at the top it was 41C so less than one minute of forced charging was the temp equivalent of 3/4mile of 10% grade.

 

Frank: Was this on the 2K3 or the 2K4? If 2K4, what did you use to take the MGx temp readings and the amp readings?

 

Dan that was on the 2k3 I think at this time only a Prius Tech with the THHT could get those values from a 2k4-5 Prius.

 

That's why I asked. Actually, Attila can get the info, he found a CAN to RS-232 adapter and has found much of the data on the bus. He's got a neat linux program.

 

So I know this is a very old thread but I was researching similar info because of my experience. I have an 05 Prius and live in the Northwest. I've had my Prius for 1 year next week and I've put over 23,000 miles on it. Let's just say that over my Honda Accord that I had, my Prius pays me to drive it!
Anyway, I digress. While driving in Montana, which I did about 5 round trips last year and I'm getting ready to do again, while driving up the Continental Divide my battery gets down to 1 pink bar. Unfortunately, because I-90 is up and down going through MT my battery is always at the 1/2 or less SOC when I hit the base of the mountain. So by the time I'm about 2/3 of the way up my battery is done. This causes me to run on only the ICE which causes me to lose speed. I actually tested a couple theories to see which would work better. Hit the base of the mountain at 75-80 mph and see how fast I would be at the top or cruise the whole way at 60 mph. The 1st theory worked best and had me finishing the hill at about 70 mph. The 2nd theory had me getting to the top at about 50 mph. It seems the momentum of the high speed works best. But there was a definite difference once the battery hit the last pink bar.
So my reason for researching this was to find out if I could do something to reach a higher SOC before the base of the mountain. I thought I read somewhere that you could put the gear selector in B while at highway speeds for a short time and it would charge your battery but use more fuel. Not an all the time thing but if needed occasionally. Anyone confirm or deny?

 

B mode won't help you in this case. There is plenty of confusion on that point. B mode dissipates energy. You could pull over to the side somewhere and force charge the batteries (foot on brake and moderate accelerator) before the ascent. But is it so bad to be going 60mph? I suspect you won't be the only one in that situation, given the terrain.

 

Thanks for the answer. I hate stopping so I won't do the force charge. Seems to be a waste of time being that in a couple minutes I'll be over the top and completely charged on the downhill side. I wish Toyota would make it so you could tell the car to charge only instead of it doing the back and forth charge/use the motor thing it always does. It should be able to charge only, for 2 minutes or 5 minutes or something like that. That way I could be fully charged when I need to be.
I have to say though, this last MT trip was with the whole family and the car loaded up and it was winter with lots of snow, ice, and slush. I thought it would harder going up the hills but it was the same. Still less than half SOC at the base of the continental divide and got low on juice about the same spot. Mileage was down but I expected that because of all the slush I was pushing through. Good trip though. My Prius handled it perfectly.

 

Why would you need to charge the battery in this fashion??

 

There is one occasion when force charging the battery can be useful. If you park facing downhill on a steep driveway or road, and need to reverse off and the HV battery is low on charge often the Prius will not move. The ICE starting while in reverse makes matters worse as the ICE tries to drive the car forwards while the MG2 tries to drive the car backwards. Force charging the battery allows MG2 to move the car backwards with full power without the ICE running.

John (Britprius)