Regen braking MS

[Wol747]

Does anyone have the real figures on how much electricity is actually recovered during regen? I've seen 80% of the kinetic energy but I've also seen 50%!
And on the same subject, do the continual spurts of regen electricity impinge on the battery longevity - or is that something no-one has looked at?

 

[brainhouston]

I've heard 80% too but it sure feels like 50% if u look at ur driving consumption...

- or is that something no-one has looked at?

most likely this lol

technically regen is same as DC charging just in short bursts...
I don't know enough about how it works exactly to know any more

 

[W Cole]

Generators are very efficient so I’d be surprised if efficiency were only 50% unless Tesla really messed something up.

Or are you factoring in wind/rolling resistance as part of the % recovered calc? That could lower the % recovered to 0% if you were slowing down at a low enough rate.

 

[W Cole]

I've heard 80% too but it sure feels like 50% if u look at ur driving consumption...

most likely this lol

technically regen is same as DC charging just in short bursts...
I don't know enough about how it works exactly to know any more

Driving consumption is taking into account wind/rolling resistance. And could be 0% if you decelerate slowly enough only using wind resistance which is a lot

 

[drtimhill]

Does anyone have the real figures on how much electricity is actually recovered during regen? I've seen 80% of the kinetic energy but I've also seen 50%!
And on the same subject, do the continual spurts of regen electricity impinge on the battery longevity - or is that something no-one has looked at?

There are a LOT of variables. Consider the car at a standstill, accelerating to speed, then using regen to come to a complete stop. How much of the energy used to move the car is recoverable? You have losses in the electric system, the drive train (motor to wheels), then you have rolling resistance in the tires, then air resistance (a lot at high speed), then the losses during regen (mechanical and electrical). I'm not surprised the spread is 50-80%, it might even be more.

Regen is just another way to charge the battery .. and generally the more gently you charge the battery the longer it lasts, though again the changes may be small and again there are many variables. Doing some kapkin math leaves regen somewhere above L2 charging but way below DC fast charging. However, if you DIDNT use regen you are just going to have to charge the battery up again later, so overall I doubt it makes any difference at all to battery life. And it's saving you $$$ and improving range. This is one of those things that it's just not worth worrying about.

 

[W Cole]

There are a LOT of variables. Consider the car at a standstill, accelerating to speed, then using regen to come to a complete stop. How much of the energy used to move the car is recoverable? You have losses in the electric system, the drive train (motor to wheels), then you have rolling resistance in the tires, then air resistance (a lot at high speed), then the losses during regen (mechanical and electrical). I'm not surprised the spread is 50-80%, it might even be more.

Regen is just another way to charge the battery .. and generally the more gently you charge the battery the longer it lasts, though again the changes may be small and again there are many variables. Doing some kapkin math leaves regen somewhere above L2 charging but way below DC fast charging. However, if you DIDNT use regen you are just going to have to charge the battery up again later, so overall I doubt it makes any difference at all to battery life. And it's saving you $$$ and improving range. This is one of those things that it's just not worth worrying about.

Exactly. If you decelerate very slowly, potentially 0% recaptured as all deceleration comes from aero and rolling resistances. If you accelerate to a low speed then decelerate using maximum regeneration and no mechanical braking maybe 50-80% (who knows…).

 

[AAKEE]

Does anyone have the real figures on how much electricity is actually recovered during regen? I've seen 80% of the kinetic energy but I've also seen 50%!
And on the same subject, do the continual spurts of regen electricity impinge on the battery longevity - or is that something no-one has looked at?

The motor that is prioritized for regen (permanent magnet motor) probably has a efficiency around 90% or so, and the charging efficieny at these higher powers probably is around 90-95%, so in total probably around 80-85% or the energy that the motor uses for regen.

About 8% of the total energy in to my battery in my S is regen charging. This car has so far, mostly longer highway trips and inly a small part of city driving.
Thats 8% of all energy charged returning to the battery!
The efficiency can not be that low to hit these numbers.

My former M3P had a higher percentage, around 10% but it had a higher part of city driving.

 

[drtimhill]

The motor that is prioritized for regen (permanent magnet motor) probably has a efficiency around 90% or so, and the charging efficieny at these higher powers probably is around 90-95%, so in total probably around 80-85% or the energy that the motor uses for regen.

About 8% of the total energy in to my battery in my S is regen charging. This car has so far, mostly longer highway trips and inly a small part of city driving.
Thats 8% of all energy charged returning to the battery!
The efficiency can not be that low to hit these numbers.
View attachment 1030992

My former M3P had a higher percentage, around 10% but it had a higher part of city driving.

If you are doing a lot go freeway driving then yes, that's what I would expect. The regen can only recover the kinetic energy of the car, which only accumulates during acceleration. Once you are "at speed" on the freeway, all the energy used by the car is consumed in keeping the car at that speed (wind and rolling resistance etc), which is not recoverable. It's in stop-and-go driving that regen helps the most.

 

[AAKEE]

If you are doing a lot go freeway driving then yes, that's what I would expect. The regen can only recover the kinetic energy of the car, which only accumulates during acceleration. Once you are "at speed" on the freeway, all the energy used by the car is consumed in keeping the car at that speed (wind and rolling resistance etc), which is not recoverable. It's in stop-and-go driving that regen helps the most.

Yes, thats the reason my M3P had more regen percentage.

Do not forget that downhills does regen (I live and drive in a medium flat area so not that much.)