Acceleration characteristics

[chrisgeary]

I've had my 2014 Auris Hybrid TS for 9 months or so now, and I'm loving it, a lot more than I expected. 

I'm curious about the way the battery/motor is used during acceleration. Say you're on a flat road, maybe 55mph or something like that. Eco mode. Lets say you want to accelerate. Accelerator input is about 3/4 of the way, the engine RPM will be quite high, nearly at the top of the power band. At this point, acceleration is mild and the Battery is still receiving charge. Now, you gently push the accelerator all the way down. RPM didn't change much but there is a noticeable kick from the motor, now it provides maximum assistance. Acceleration is now fairly brisk, indeed 50-70mph is actually pretty impressive. 

My question, really an observation I suppose, is... why doesn't Toyota provide more Battery assist earlier on? If I've been travelling long enough, my Battery will be 2 bars from full (so at its normal maintained charge). It seems to me that instead of increasing RPM for those moments of 3/4 throttle accelerations (or indeed climbing a slight incline), that battery charge could be used instead and then replenished during any subsequent coasting/downhill. It would reduce the annoying high engine RPM and, possibly, improve efficiency (it's already excellent so no complaints there).

[Bob110023]

I think it's to do with the emf. Some people call it electro motive force or electro magnetic force. These force's are given off with every electric motor at some stage. Take the old electric milkfloat, if the speed was excessive going down over a hill the emf  given off would actually be enough to stop the milkfloat very abruptly by ripping out it's propshaft.🤤

[Gerg]

On the early gen 3 Prius cars (2009 - 2010?), there was a recall for a software update that related to the inverter, I believe.  If I understood this correctly, owners reported that they noticed that low-speed electric performance was weaker after the code had been updated.  On another forum I read that the code upgrade was to prevent some early life failures that were occurring on the inverter.

Perhaps it is to protect the inverter or extend the battery's life?

The gen 4 engine  (2016 Prius, C-HR, new Corolla) has reduced the 'mooing' that you mention that the gen 3 engines descend into when accelerating with any spirit.  This gen 4 engine is largely the same as the gen 3, I believe, but the transmission is all-new, and now uses two internal shafts instead of one.  This has allowed different internal gearing, and perhaps different electric motor dimensions (and therefore safe rotational speeds?).  The net result is that the 'mooing' is reduced, and the electric drive will work up to a higher speed etc. The drive is better, the economy is better, yet the total 'system' horsepower is less.  Odd.

I wish I knew.

[chrisgeary]

I did wonder if gen 4 might address some of these things, I'm looking forward to trying it out one day.