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Possible Change to Battery Heating / Range Mode in Version 7

Andyw2100

Well-Known Member
Oct 22, 2014
6,542
2,393
Ithaca, NY
I think there's a chance Tesla has made a change, and the cars may now, in version 7 of the firmware, be heating the pack under certain circumstances when they weren't in the past. It would be great if others could test this, and report what you find.

Here's what happened with me tonight that makes me believe something has changed. I think it is one of two things. Either the pack can now heat if the cabin is preheating, even if range mode is on, or the pack can heat if the cabin is preheating and the car is plugged in, irrespective of range mode, or some combination of the two.

I had left the car in the garage for a few hours, plugged in, but not charging, and on the way back to it, in anticipation of taking it on an hour's drive, I started preheating the cabin, planning on heating the battery pack, because it was cold enough that I definitely expected a regen limit. When I got in the car I found that I had forgotten to turn range mode off earlier, and thus expected to see a regen limit because of that. I did not.

The car had been sitting for about four hours, after having been driven for about an hour earlier. The temperature outside was about 38 F. My garage may have been 10 to 15 degrees warmer.

To provide a comparison, earlier in the day after a couple of short drives, the car did display a regen limit after sitting for about an hour outside in 50 F or 55 F temperature.

I can not be 100% certain that version 7 represents a change in behavior, based on this one example, but I'm leaning strongly that way.

As a reminder, in the past, the battery would not heat at all if range mode was on, unless the car was charging. Just being plugged in would not heat the pack, and preheating the car would not heat the pack if range mode was on. With range mode off, preheating the car would also heat the pack.

I believe that tonight my pack heated, just as if range mode was off, but with range mode on.

Interested to hear what others are finding. I'll test more myself as it gets colder too.
 

apacheguy

S Sig #255
Oct 21, 2012
5,090
1,247
So Cal
Active pack heating begins somewhere in the mid 40s. We know this from the diag screens. I suppose it's possible the 50-55 degrees earlier in the day were cold enough to display a regen limit but the BMS did not request heating until the temps dropped and this is when the regen limit disappeared.
 

Andyw2100

Well-Known Member
Oct 22, 2014
6,542
2,393
Ithaca, NY
Active pack heating begins somewhere in the mid 40s. We know this from the diag screens. I suppose it's possible the 50-55 degrees earlier in the day were cold enough to display a regen limit but the BMS did not request heating until the temps dropped and this is when the regen limit disappeared.

In my experience I don't believe active pack heating has ever completely eliminated the regen limit. I think if it is cold enough for active pack heating to kick in, the regen limit may be reduced, but the pack isn't heated enough to eliminate it.
 

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