Forcing an HV battery charge

<div class='quotetop'>QUOTE(Tideland Prius @ Nov 23 2007, 11:35 PM) [snapback]543519[/snapback]</div>

<div class='quotetop'>QUOTE(efusco @ Nov 24 2007, 03:45 AM) [snapback]543537[/snapback]</div>

You can also burn out your MG-2 (motor-generator 2, the one connected to the wheels) this way. It's probably the only thing you can do to over-ride the car's own built-in protection. At the alternative fuel fair in Lacey, WA, a year ago, Frank Hudon, who somtimes posts here on PC, showed us a motor that was burned out this way: The foot on the accelerator tells the car you want to go, so it sends current to MG-2. But because you've got your foot on the brake, and MG-2 is connected to the wheels via a fixed reduction gear, it cannot turn. Sending current to an electric motor while it is prevented from turning can burn it out.

 

We do indeed suggest force-charging before an MPG competition,
even if it pushes the numbers a little artificially high -- we did
this for the press people at HF, and they turned in solid eighties
and thought it was *wonderful*.
.
There is no appreciable, winding-damaging current sent through MG2
during force-charging. If you're holding the brake down firmly,
there's *no* current sent through it. Even the hill-holding torque
at standstill with the foot off the brake only pulls an amp or two
from the HV battery over and above the various parasitics.
.
_H*

 

<div class='quotetop'>QUOTE(daniel @ Nov 24 2007, 09:41 AM) [snapback]543554[/snapback]</div>

That doesn't make sense.

Where is the current going to come from?

From the battery? No, because current is going INTO it.
So, the only source of current would be from MG-1.

But, MG-1 is about 1/2 the size and power of MG-2, and some (most? all?) of its current is going into the battery.

So, given the that MG-2 is about twice the rating of MG-1, and that some (most? all?) of the current from MG-1 is going into the battery, is there even enough juice available to damage MG-2?

Plus, the computer knows that your foot is on the brake, and the gas pedal is entirely electronic, so this is being done with the computer's full cooperation and consent. If the computer REALLY thought you wanted to accelerate, wouldn't it be pulling current OUT of the battery and into MG-2 to increase torque?

I suspect that the computer is bright enough not to let the loose nut behind the wheel damage the hybrid system by such a simple act - you probably have to be much more clever in order to kill it.

 

Just be aware that you may be shortening the HV battery life if you run the Prius like a series hybrid (force charging and then runs on HV battery).

The HV battery was intended to be used when the ICE is very inefficient. Stealthing through that bumper to bumper strip of road is a good way to use the HV battery power. However, force charging just to run 5 miles on electric only sounds more like an abuse on the HV pack.

 

I was just going by what Frank told me. Check with him. I believe he's a Prius mechanic. He showed us a burned-out MG-2 and said this was how it happened. Maybe Galaxee's DH can give us some insight into this.

 

I tried this once with my classic, and it made a really horrible noise, so I stopped. Do you know if this is ok for a classic?