Answer Me This Prius Vee’erz w/ ScanGauge Or Other TechnoKnowledgable Petrol Warfighters

I have studied the (traction) Battery Amps , Friction Brake Sensor, along with Hybrid System Indicator (HDI). I was trying to determine why it was so easy to glide in my wife's Gen II (no arrows on energy display) and so hard to glide in my Prius v (gave up on no arrows and try instead for no green or white bars on HSI). I found that flickering green or white, or even just into solid green, on the HSI on my Prius v (wagon) was very similar to no arrows on energy display in Gen II, in that they both showed single digit amp draw on the traction battery. Under these glide conditions the Gen II would draw 5 amps (+/- 3) and the Prius v (wagon) would draw 5 amps (+/- 4). That felt good. First time I wrote that observation up. Still need to get some video to back it up and share with PC.

Now to answer your question. I believe that the three white bars of the Hybrid System Indicator (HDI) in the charge area (p 201 Owners Manual) indicate amount of charge going back into the traction battery. The Friction Brake Sensor does not register any friction brake usage until the traction battery says uncle because there are too many amps going into it. This is for gradual braking that I do %99 of the time. It might be different for abrupt braking. The 3rd white bar is not the max regenerative charge, but rather the beginning of the highest range. I often see the third white bar light up and no friction braking indicated. The third white bar comes on around 55 amps and then if I nudge the brake a little more I will see the regen amps get into the eighties or occasionally briefly into the nineties before I see the friction brakes blended into the stopping action. I am quite amazed how smoothly it blends friction and regen braking. All these amp values are from memory and should be considered approximate. I will try to get some video of this to share and nail down regen amp values for the different white bars. Best guess is 1st white bar is 0 - 24 amps, 2nd white bar is 25 - 54, and 3rd white bar is 55 - 97 of traction battery charging amps.

I found one weird situation when the white bars do not represent regen charge going back into the traction battery. If you are using regen braking and you hit (bump or pothole) or slip (wet manhole cover or slippery patch) it switches off regen braking and uses friction braking only. Some people describe this switch as feeling like an acceleration. When this happens I see the Friction Brake Sensor value jump and the regen amps disappear but the white bars stay lit. I have thought of writing Toyoda about this to see what they say.

ScanGuages from here; Welcome to Google Docs
(traction) Battery Amps on line 25
Friction Brake Sensor on line 74

 

Could the below be the ABS kicking in due to uneven traction? Doubt ABS works with regen


"I found one weird situation when the white bars do not represent regen charge going back into the traction battery. If you are using regen braking and you hit (bump or pothole) or slip (wet manhole cover or slippery patch) it switches off regen braking and uses friction braking only. Some people describe this switch as feeling like an acceleration. When this happens I see the Friction Brake Sensor value jump and the regen amps disappear but the white bars stay lit. I have thought of writing Toyoda about this to see what they say."

 

It is just the well known "hit a bump and felt Prius accelerate" issue, caused by wheel slippage shutting down regen. But it's weird that the white charge bars stay lit after it has switched to friction braking and there is no regen going on.