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Discussion in 'Model 3' started by argon2018, Feb 11, 2019 at 6:20 PM.
any idea why?
Because when the battery is cold, it can't accept charge very quickly. The regen braking is based on pushing electricity into the battery, and if the battery can't take it, you can't do the braking.
If your battery is warm because you've recently been charging, or if the battery warms up after you start driving, you'll see the regen creep back up to normal.
Cold batteries don't charge as well.
You can actually damage the battery by trying to force too much current into it when it's cold. Heavy regen produces lots of current, which is why Telsa limits regen at non-optimal temperatures.
Lithium Ion batteries have a negative temperature coefficient, which means the colder they are the more resistance they have. When they have a higher resistance they simply cannot pass as much current, which in turn limits your regen.
First of all it's BRAKE not BREAK.
I like the title of your thread asking if there are any geniuses out there.
Answer = plenty. ( But only a few know what they are talking about ). lol
I imagine a higher peak current can be drawn from the battery when driving than the amount of peak current returned during regen. On cold mornings I get the limited regen alert, but no indication of limited driving power.
I've received both. I've received both the regen alert as well as the limited battery power alert. Of course it was -20F outside.
I was a bit surprised that at 57F triggers it, parked in the garage.
Limited regen isn't really impacted by cold, it's the battery that is.
When you charge to 100%, you are going to get limited regen in the summer. Regen is the charging of the battery from coasting. If the battery is full, it doesn't accept any more charge and therefore the regen has no where to go.
When the battery is cold, the overall capacity is less and therefore the ability to charge / regen is even worse.
This is the part of the story I have trouble understanding but I suppose it means that the energy wants out of its bottle
2nd law of thermodynamics. that battery wants to come into equilibrium (of charge) with its environment all by itself
Given sufficiently cold weather, you will see the throttle-side limited too. It's much harder to trigger. All of this is Tesla keeping the battery as healthy as possible. If other EVs have "better" regen, you first have to question if they even considered battery longevity into their design decisions.
Short answer; to protect the battery.
Maybe we can do an experiment to find out what the car/battery/regen really feels like.
When its -20F - Take off all of your clothes ( cars are naked unless they are wrapped in ppf or something ) and stand outside and try to eat something after being out there for …..lets say.....4 hours of just standing. How much regen ( food ) can you consume?
Then come back to the thread and lets see what you tttttyytytyyyyyyyypppppyyppepepepppppeeeeee.
mod note: title amended for clarity.
I liked the un-clarity. It was fun.
( too much seriousness ) <-----oops did I say that out loud?
Oh well...let me sneak somewhere else and have a little fun.
Wishlist / improvements / enhancements (RFEs)
Too bad they can't route some of the current through the heater. That way regen feel could stay constant. I hate when regen doesn't work the same as it usually does.
There's a balance to be struck in heating the battery for the purposes of regeneration. In most cases, you'd use more energy getting the battery to a state where it can accept "normal" regeneration than you'd ever recapture from the regeneration itself. If it's just the quality of the drive that bothers people, maybe Tesla could introduce some kind of friction brake regeneration "simulator" to appease. But that seems over the top.
Battery? Heck I was talking about heating the car's interior on a cold day but heating the battery would be nice too.