Message: Regenerative Braking May Be Limited....

[Joyride]

I was driving to work the other day and dropped the car into B mode not long after turning it on and got the message below in the right-hand dash area:
"Regenerative Braking May Be Limited. Vehicle Deceleration When Coasting May Be Reduced."

The morning was fairly cold, in the low 50s and after about 10 minutes of driving, the message stopped appearing in the window when I put the car into B mode.

Has anyone else seen this before? Any ideas what would cause it to appear? My guess is that it's something to do with the outside ambient temperature, but that's really just a guess.

 

[Dsinned]

http://www.myrav4ev.com/forum/viewtopic.php?f=8&t=145

Seems to be a reoccurring cold weather phenomena in RAV4 EVs. I see it happen too but only when it is quite cold outside. After driving the car awhile, it generally goes away, and even while it is still occuring, it does not seem like regenerative braking (in "B" mode) has become completely disabled; just slightly impaired . . . maybe.

 

[Luke26]

Does anyone know if the brake lights come on while decelerating in B mode, like the Model S?

 

[Luke26]

Does anyone know if the brake lights come on while decelerating in B mode, like the Model S?

I checked this evening and the brake lights do not come on.

 

[miimura]

Tesla limits the amount of regen when the battery is full. There is really nowhere for the energy to go. This was discussed in one of their early engineering blog posts. I'm sure it applies to the RAV4EV as well.

 

[Dsinned]

miimura, it has to be more than just that reason, because I have seen this same thing happen on my RAV EV, always in cold weather initially while driving, even on a significantly depleted battery.

 

[TonyWilliams]

Regen must be limited at the top of the charge, and also is limited the colder the battery gets.

The same is true when charging. If the battery is cold, charging time will increase, sometimes significantly.

 

[SeattleRav4]

A little data to add
Yesterday, after mine sat all day in the parking lot, OAT 46 degrees F, Range 26 miles: "B" produced the Regen Limited message.
This morning after Timed Standard Charge and Climate Preset, OAT 46 degrees F, Range 86 miles: "B" worked as expected. I have a pretty steep downhill just outside my driveway.
If the Regen message occurs when fully charged, it must be on an Extended charge.
Clearly the cold battery is one cause of the Regen Limited message.

 

[TonyWilliams]

Guys, you're trying to reinvent the wheel here. Yes, cold batteries charge and regen slower and 100% can't take more charge / regen.

Other variables are the TMS warming the battery. It won't do it at a low state of charge (sorry, don't know the threshold, but the climate control threshold is 50% SOC). And there's no doubt a variable of whether the car is plugged in or not to power the TMS.

 

[Brandy]

OK, I payed attention this morning. Standard charge with pre-heat. Before I left the drive way I selected 'B' mode and no regen warning panel. I've see it going into work and selecting 'B' never understood why.

I does look like the temp of the traction pack is the reason. I guess with the car connected over night the pack was pre-heated.

=D~~ Brandy

 

[Brandy]

I saw an interesting result on the 'limited regen' today. Overnight charged and pre-heat completed on time and as I left for work I put the car into 'B' mode, no warning. Where I was parked it was a bit shady when I went out to another building the warning came on, no real reduction in regen-braking noticeable, same on the way back.

So I parked so the noon day sun would warm the front of the car. When I made the trip in the afternoon no warning the car was very warm. The sun did not reach the battery pack under the car but it did warm up the whole front of the car. Not sure what it all means I wish we had a read out of battery temp now.

=D~~ Brandy