Whisky
Member
How do you know it's from SoC and not from the battery heating up from driving the car?
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Regenerative braking will be limited?
- Thread starter bigroccrek
- Start date
How do you know it's from SoC and not from the battery heating up from driving the car?
Being in the high desert mountain foothills, it's no surprise that you're seeing regen limits this time of year.
Up in the SoCal mountains, our family normally avoids charging the Model 3 much above 80%. Even then, our regen is somewhat limited even right after charging the car. This is the case with our Model S 85 as well. It does seem to me, though, that the Model 3 might be limiting regen a bit more than the Model S, given equal temperature and SOC (state of charge). When we descend our mountain (4900' / 1500m drop), the regen usually gets a bit more limited as we continue to descend, not a surprise because we are regenning continuously.
Leaving a mountain in an EV can be a balancing act, because on the one hand you may want to have a high SOC for all of the day's driving, while on the other hand you don't want regen to be excessively limited. At least with a Tesla (unlike our old LEAF), you can crank up the heater if you need a bit more regen in order to avoid riding the brakes.
diamond.g
Active Member
It could be. If supercharging was free I would try to charge to 90 and see if I have regen. In past experiences I have has some regen limitation when charging to 90 from WC and leaving for the day even during the summertime.
ℬête Noire
Active Member
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Heating the battery a bit from that ambient temp actually helps. Battery seems to like closer to 80F (trade off occurs w/passengers wanting A/C).
I see regen dots at 85% getting in from a 60F-70F overnight, too.
I'm not an expert, but I was told that regenerative braking is limited if:
1) If the battery is too cold, it's too hard for the battery to accept the charge (increased resistance)
2) If the battery is near full charge, regen is limited to prevent the battery getting too fully charged. I'm not sure what the charge percentage is the magic number. In my X, I routinely charge to 90% and I have no problems.
The reason I started charging higher is because of this video.
1) If the battery is too cold, it's too hard for the battery to accept the charge (increased resistance)
2) If the battery is near full charge, regen is limited to prevent the battery getting too fully charged. I'm not sure what the charge percentage is the magic number. In my X, I routinely charge to 90% and I have no problems.
The reason I started charging higher is because of this video.
The temperature effect on regen braking is much more dramatic with my M3 than I expected. 60F in Toronto at 50% SOC and I get the limited regen warning with the dots passed the D. We also have. A Nissan Leaf, which has a very nice one pedal driving feature, and we don’t see the drop in regen until you get below freezing. The Tesla is a more advanced vehicle, so it is hard to explain why it is more limited in this area.
diamond.g
Active Member
It appears Tesla batteries are happiest around 30°C, but accept the highest charge rate at around 50°C.
What was the temperature over the prior 8+ hours? The thermal mass of the battery pack is pretty significant. On a relatively warm autumn day, the battery may still be cold if it was parked outdoors or in a cold garage overnight. However, if the battery temperature is actually 60F / 16C, then I would be surprised if regen is being limited at 50% SOC; that would be unusual.
I'm surprised that your Nissan LEAF is allowing so much regen at lower temperatures. Perhaps Nissan is being less conservative than Tesla in their battery management. Unlike the LEAF, of course, the Model 3 will perform active thermal management, so it'll warm up a cold battery as you drive and give you more regen.
That could be it, we have had some near freezing nights, and that is a large battery mass, but I thought the active temperature management would bring it up quicker.
With the single pedal driving on the Leaf (which I think Tesla should copy) mechanical brakes are seamlessly brought in as needed to supplement regen, when you let up on the accelerator. So you don’t notice any regen fade, and don’t need to be warned braking will not be what you are used to in warmer weather. Can anybody see a reason Tesla should not do this as well?
With the single pedal driving on the Leaf (which I think Tesla should copy) mechanical brakes are seamlessly brought in as needed to supplement regen, when you let up on the accelerator. So you don’t notice any regen fade, and don’t need to be warned braking will not be what you are used to in warmer weather. Can anybody see a reason Tesla should not do this as well?
diamond.g
Active Member
It takes some time to heat such a large mass.
Tesla doesn’t do blended brakes because they don’t seem to like the experience (pedal feel I suppose). They could do it (I Booster is actuated by AP already) but choose not to.
Personally I like the separation as I know that if I am not slowing down enough I can stab the stop pedal, and the stop pedal feel won’t change based on grip levels.
I like Tesla’s current system, as it helps me to use the mechanical (friction) brakes as little as possible. If I see that less regen is available, then I can leave more room to slow down, and I don’t have to worry about inadvertently using the brakes as I lift off the accelerator. This is particularly important when descending mountain grades regularly (as I do) because you want to minimize wear and heating of the brakes. In general, it’s helpful for efficiency and maximizing range.
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