Limited regen going downhill

[gregincal]

I had something happen on my 3 this morning that has never happened on my S.

My commute involves a 1800' climb over a pass followed by an 1800' descent. I usually get a couple kWh back going downhill (although I spend a lot more than that on the climb).

This morning it was raining and about 50°. I started with a normal 90% charge and there was nothing unusual about leaving the house and climbing, but about halfway down the descent I got a limited regen notice. Usually I never have to use brakes descending unless traffic forces me to, but now I had to occasionally apply light pressure to slow enough for some of the downhill curves. I had a fair amount of regen, but definitely not full. When I reached level ground at the bottom of the mountain the warning went away.

Has anybody else gotten a limited regen warning descending when nothing else should have caused it (too warm to be temperature and the battery wasn't close to full).

 

[cpa]

We have not had that much experience with our 3 as yet, just 400 miles on the odometer. We had no limitations on regeneration descending Pacheco Pass last week.

I did notice, however, that the blue snowflake appeared on the screen next to the picture of the tiny battery yesterday morning when the temperature was around 58 degrees, and the battery was around 22%.

There is probably no correlation between the snowflake and regen, but thought that I would toss this out there.

 

[DOCAL]

Not got my Model 3 yet, but I have had this happen in my Model S.
IIRC I left Murphys CA at 90%, and drove up hill to the big trees national park, did not charge, and then on the way back down, after a significant time spent with heavy regen it started limiting it.

Still ended up with more juice in the battery at the bottom of the hill than at the top though

 

[David99]

In the Model S it starts to limit regen when the battery is below 20 Celsius (68 F) or when the battery is 90% or higher. I would expect the Model 3 to have similar limitations. If you drove up the hill before at 50 F, then the battery temperature should not be an issue. If you started with 90 and climbed the hill you should also not hit the 90% limit on the way down. In other words, there must be something else the Model 3 doesn't like.

 

[gregincal]

In the Model S it starts to limit regen when the battery is below 20 Celsius (68 F) or when the battery is 90% or higher. I would expect the Model 3 to have similar limitations. If you drove up the hill before at 50 F, then the battery temperature should not be an issue. If you started with 90 and climbed the hill you should also not hit the 90% limit on the way down. In other words, there must be something else the Model 3 doesn't like.

Basically that's what I figured. It definitely doesn't seem like it could be temperature, since I've driven my S in far colder conditions, and once limited regen goes away it doesn't come back again (and I didn't even have limited regen when I started off this morning). We'll see if it happens again (this is only the second time I've made this drive).

 

[gregincal]

Happened again for the second day in the row. I might have to experiment whether starting at 80% instead of 90% makes a difference (although the battery is at 80% when I get limited). I think I'm going to have to contact Tesla about this. It would be bad if regen wasn't able to capture all the energy coming down from a pass.

 

[animorph]

Not a firmware change?

Could be the regen electronics overheating with the long period of regen. Or a bad sensor that only thinks it is overheating. Odd enough that I'd check in with the SvC and see if they have an idea.

 

[jerjozwik]

at a reasonable 21*c i had regen limited going down a not too step hill. i was kind of surprised to see it. elevation change was 277m over 3.3km. battery was between 70-80%

 

[GregRF]

Any updates on this?

 

[gregincal]

I think charging to a lower percentage has solved this, but I haven't done enough controlled experiments to be sure. At the beginning I was charging to 90% overnight and the battery was at about 80% going downhill, and I was limited pretty much every time about halfway down the mountain. Now I charge to 75% overnight and it doesn't seem to do it any more. I'll have to try charging to 90% again and see if it comes back.

 

[DanL3]

Also you could try doing a charge to 100% then see if 90% works better after that. I do not know what Tesla's balance algorithm is but most battery packs balance better close to 100%. The issue you are seeing is clearly Tesla's way to protect all the cells if the pack deviates a little from the optimum state of balance.

 

[Super Gizmo]

I had the same issue yesterday after charging to 90% and then going down HWY 1 grade towards Pacifica, CA with about 80% charge.

 

[shs1]

My trip down to town involves about a 2000' loss in elevation, and with our Model S I never saw limited regeneration unless I had done a full charge. With our 3, starting 75-80% charge, I now get limited regeneration that comes and goes as we drive down. Temp in the 50s (F). It is annoying as one pedal driving is one of the joys of driving a Tesla on mountain roads.

 

[SigNC]

Anybody know what kind of power full regen is putting into the battery?

 

[MikeBur]

The issue you are seeing is clearly Tesla's way to protect all the cells if the pack deviates a little from the optimum state of balance.

Not necessarily. It could potentially be a number of additional things: overheating motors due to new coolant system not able to dump energy into already warm battery, thermal protection on inverter/module, etc. There are enough new pieces that this isn’t a given.

Anybody know what kind of power full regen is putting into the battery?

Most I’ve seen is around 26kW instantaneous at 42% SoC, using TeslaFi

 

[MikeBur]

My trip down to town involves about a 2000' loss in elevation, and with our Model S I never saw limited regeneration unless I had done a full charge. With our 3, starting 75-80% charge, I now get limited regeneration that comes and goes as we drive down. Temp in the 50s (F). It is annoying as one pedal driving is one of the joys of driving a Tesla on mountain roads.

What’s SoC start and end?
Have you tried using TACC to limit speed (where safe obviously )

 

[Zoomit]

Most I’ve seen is around 26kW instantaneous at 42% SoC, using TeslaFi

Wow, that’s ...not a lot. Should be double that or more. Very curious to hear if/when you have updates.

 

[gregincal]

My trip down to town involves about a 2000' loss in elevation, and with our Model S I never saw limited regeneration unless I had done a full charge. With our 3, starting 75-80% charge, I now get limited regeneration that comes and goes as we drive down. Temp in the 50s (F). It is annoying as one pedal driving is one of the joys of driving a Tesla on mountain roads.

I’d be curious whether starting with a 60% charge (assuming that’s enough for you) solves the problem.

 

[run-the-joules]

I had this pop up yesterday when coming back from the Oakland hills. As you'll see in the image, I was nowhere remotely close to a full charge, and you can't see it in the pic but it was around 55°F, so not particularly cold.

 

[gregincal]

I had this pop up yesterday when coming back from the Oakland hills. As you'll see in the image, I was nowhere remotely close to a full charge, and you can't see it in the pic but it was around 55°F, so not particularly cold.

I was driving in this morning with a higher charge and 43° and did not get any regen limiting. If it's something overheating than colder weather would help.