13 seconds zero to 60? How full was the battery? The HCH2 does 0 to 60 in about 10 seconds, with a nearly full battery, without any power braking.

 

I understand from a poster in Prius_Technical_Stuff that this is just 0.3 seconds slower than the published performance specs for my model Prius. The SOC was slightly above the normal 60% because the protocol starts with a 'forced charge' but only for about five seconds. I held it there long enough to get the ICE up to maximum rpm and then took my foot off of the brake.

We had discussed the technical characteristics of 'forced charge' and after making sure there was no risk of overheating, I began to wonder what happens when I take my foot off the brake. The answer is a maximum acceleration for this vehicle but with a fraction of the noise and fury of ordinary vehicles.

During forced charge, the ICE puts out about 15,000 watts and the battery absorbs about 12,000 watts. That leaves about 3,000 watts to heat MG2, which is held by the brakes. Since the lower 1/3d of the MG2 stator windings are in the transmission oil, they are well protected. The upper 2/3d would only have to deal with 2,000 watts. The construction and aluminum case means the upper stator windings should not have a problem for short intervals.

Bob Wilson

 

You should read more carefully. Bob's Prius is the older model (NHW11, 2001-2003). The newer one (NHW20, 2004-2007-2008?, a new model is about due) has about the same acceleration as your HCH2. Comparisons of the Older Prius to the original HCH are appropriate.

JeffD

 

Darn:

http://www.dragtimes.com/Honda--Civi...ag-Racing.html

Looks like this one has a problem, 18.3 seconds, like my old 2003, NHW11 Prius.

Bob Wilson

 

Does WOT and brakes mess up the CVT? Also, were you in the lower gear range? The 'S' (HCH I) range if you will?

The HCH will rev to redline and hold almost instantly (from a dead stop). I don't think it takes 13sec to get there either. I'll have to check this out

 

The first time I tried it, I saw 65 Nm on MG2 and was concerned about overheating. Later, I found the ICE was generating ~15,000 W. and the battery taking ~12,000 W. leaving only 3,000 W., worst case. The lower third of MG2 is in the transaxle bath so only 2,000 W. has to be handled by the upper 2/3ds and this is rather modest.

I do not recommend it for an extended period of time but 5-10 seconds should be no problem at all.

Ahem, 18.310 seconds according to the one entry in "dragtimes.com". Still we have a 1/8 mile track in Huntsville and for $15, I can get a time-slip. . . . Sounds like fun.

Bob Wilson

 

By pressing the brakes in WOT mode, does this effectively turn off the battery power until the brakes are let go? If not, are you getting any wheel slipage at all?

 

It turns out the control computers detect the condition and reduce the current to MG2. But once it starts spinning, it really takes off. I've recorded the data but haven't gone back and done a second-by-second analysis. Still, it does move out quite nicely.

The only wheel slipping occurred Thursday evening when I wanted to make a left turn faster than the car to my left (two left turn lanes.) About 60 degrees in the 90 degree turn I head a little tire 'chirp.' Regardless, I had complete control although it happened much faster than I was used to seeing.

Bob Wilson

 

So is the engine under load at this point, brakes/WOT? If not, I heard it's bad to redline without being under load.

Redline in neutral, equals bad for the engine, redline in gear, no problem.