How to get enough power in Reverse?

Wait, what? Reverse only uses the electric motor? Is that true? That doesn't sound right.

 

Whoa, this would be good to know. It will probably be quite a while before I find my C off road, but if there are any kinds of limitations to reverse, it would be good to know in advance.

 

Yes, only motor power in reverse. If the traction battery is low, you can force gen with brake on in D and WOT. Other than that, no torque/power from the engine in R.

 

Technically, I can experience this each single day, since I reverse in my garage all the time. I have a little bump (about an inch in elevation difference between my driveway and the floor in my garage) and if because of any reason I will stop and my front wheels will be right before this bump there is no way my C can "lift" its front axle on this bump from the full stop while reversing. It was a huge surprise to me a week or so after I bought the car (since I've never owned a hybrid before) but now I just got use to it. All I do is just use the momentum to get into my garage. However, my lesson was learned in easy way, so there is no way that I will leave the car facing downhill knowing that I need to reverse later somewhere in the middle of nowhere. I've heard that the same issue was on early models of Prius; however, it was solved later on. I wonder if it can be solved with C.

And flooring will not help by the way, unless you will start rocking. If you will just push the pedal to the metal, all you going to hear is a "typical" electric noise of a "kinda" overloaded motor. That's it, nothing else.

 

See: Toyota Prius - Power Split Device for how the Prius PSD works. Play with the sliders and you will see how to get reverse. Note for example that having the ICE engine running actually make reverse MORE difficult. If the battery needs charging, let the ice finish before attempting to reverse. If the ground is loose, check that you are getting traction.

Park so that you are going forward, and downhill, to leave, if at all possible.

 

Wow, I'm glad I'm finding out about this. Happens to be two days after I parked somewhere where I had to reverse uphill to leave, but thankfully it wasn't so steep that I was stuck. Definitely something I'll keep in mind from now on.

 

I wonder if it will be possible to find some info on a maximum angle under which MG2 is going to push the C out in reverse from a full stop?

 

I had this same thing happen to me the first time I backed into my garage.
I still get goose bumps thinking about the noise the motor made.

 

Yep, that's exactly how I felt .

 

On the weekend I decided to reverse up a friend's steep driveway. I've previously gone up it forwards in EV mode only so I knew it could be done.

In reverse there was a slight difference in that I was going really slowly. He lives on a battle-axe block, with a long, narrow and steep driveway - but what's worse is that it has a kink in the middle of it with a wall on one side and drop-off and foliage on the other side. Navigating that kink is a right pain, but generally in the past I've preferred always going up backwards and I've decided the same applies to the c.

What's nice about the Prius is that the electric motor doesn't mind climbing steep hills slowly and carefully, but what was interesting going in reverse was that I was clearly testing its limits.

In a surprising twist, as I gently eased my way through that kink in the driveway - the ICE came on. It wasn't loud and it came on long enough just to give the car a little extra kick to get it rolling backwards up the hill again, then it promptly turned off and left it to the electrics. It happened once more briefly as I completed the operation. I had a good charge on the HV battery at the time.

The car wasn't screaming in pain - to the contrary it seemed to just be calmly dealing with the situation - it just didn't allow me a 100% stealth arrival in reverse.

 

Happened again today - the ICE came on when I was reversing on a slope, which wasn't even that steep. It came as a surprise but I guess I pushed a little harder than I normally would in reverse. Again the SoC was not the reason.

 

Prius doesn't shift gear so it reverses with the MG2 spinning backward. The good thing about it is you don't have to wait until the gear shift to finish like in regular auto tranny. You can put it into R eventhough you are still moving slowly forward.

You can also rock the car forward and backward quickly and smoothly. Very helpful in the snow if you get stuck.

 

Serious case of prius fever...

 

How come we haven't heard from anyone in San Francisco regarding this problem ?

 

Parking... in San Francisco?

 

I don't have problem back into a ramps when I installed my hitch...

 

My driveway lifts about 4 feet over a distance of 40 feet up to the main road so a 10% grade. I have never noticed difficulty or even thought about the fact that I back out of my garage up to the road in my new Prius C2. Friends have told me they consider my driveway "fairly steep". This thread is the first I have thought about reverse.

As long as you are rolling I don't imagine there will be many times that 20 Hp will not be enough to do what you need. Remember, putting a 2x4 under a wheel is considered a pretty decent chock. Try backing over two wheels chocked like that with a conventional car and you will be surprised how much power it takes, although it can be done. I am surprised that it can't overcome a 1" bump from a standstill though, that is good to know and it only makes sense to park "nose down" if possible on a steep grade given this limitation, especially if deep loose gravel is involved.

Considering the huge simplification of reversing power to a motor vs adding a reverse gear to the CVT, I can understand why they did it this way.

 

it's recommended to never "rock" a HSD system.. ever... (i'm sure there are technicals here on priuschat somewhere)

as Corwyn browsed over. the ICE kicking in does kinda make it more difficult. The momentum is all from MG2. as the voltage drops in your battery, it naturally gets weaker. So.. the engine runs as a generator to spin MG1. Well... your voltage starts to climb again which provided torque but MG2 has to fight the whole process... therefor the loss.