Why doesn't regen damage the battery?

[hifi239]

I read that Taycans can regen as much as 290kW. If the battery isn't preconditioned and warm, why is this power level not damaging it?

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[daveo4EV]

too brief - and it's not sitting there - batteries degrade in terms of a full cycle charge - from about %5 (or less) to 98% (or more) is considered a "full" cycle…

charging/discharging that is less than a "full cycle" is a "partial" cycle - and has way way less impact...

industrial/automotive/consumer grade LiON batteries are rated from 1000 to 5000 "full cycles" depending on the quality of the LiON and it's usage patterns…from what we can discern Taycan class batteries are expect to last anywhere from 800-1400'ish "full cycles" - hence the 8 year/100,000 mile warranty - charging from 40% to 80% each day is _NOT_ a full cycle - or even close.

even for a long downhill stretch (like I-80 coming down from Tahoe) it's still only a partial cycle in terms of the batteries overall longevity…

and regen is slow the vehicle losing kinetic energy and therefor does not contribute "peak" kW's for very long …and once you're below 150 kW or less contributed power it's not that hard on the battery cells…

regen contributes to battery wear as all part of the whole "charge/discharge" cycle count , but no where near as much as a sustained 42 min 270-50 kW charge from 3% to 98% where 268 kW can be sustained until at least 50% SOC…

Regen’s contribution to your battery wear/tear is fractional vs. say charging it to 100% and parking it outside in the sun during a heat wave…regen is not your concern.

 

[WasserGKuehlt]

the regen probably also depends on the condition of the battery, it doesn't have to be max power into the battery (for the same brake pedal force).

 

[alexsas]

I was sharing my findings in one of the heater posts.

it looks like there’s a management system that puts any excessive (for the battery) generated power into a high voltage heater. So even if they claim true 200kw+ regen it doesn’t necessarily go to the battery

 

[McgR]

The most interesting thing here is : what should you do when going home after a trip in the mountains with 30 km downhill to start with. When charging to 100% regenerative braking would not be available. Would this reducing the braking potential of the car. Or would it be better to charge to 80% ? And arrive with 100 % down hill anyway with the regen. Probably the last.

side note: just went over the owner manual of the Panamera. In sport mode it charges the battery but maximum to 80% for two reasons. After 80% it is less effective but also to keep battery free for regenerative braking. Completely different system of course and lot less powerful regen braking compared to the Taycan.

And for the 270 kw regen : this are only peak moments I presume. Unless driving continuously down hill on a really steep slope.

 

[RAHRCR]

The key is that the regen is up to 270kw. Pretty sure that the amount of charge to the battery is governed by its state of readiness…..SoC, temp, etc….

 

[RacingDuck]

It's just a bit of physics and math:

Porsche says they recuperate up to 0.4 g. You'd hit the power limit when doing that kind of braking only at 130 mph.

The power requirement for normal braking at normal speeds is not an issue for the battery.

If it were, the system will limit the regenerative braking to acceptable limits and apply the normal brakes instead.

 

[alexsas]

The most interesting thing here is : what should you do when going home after a trip in the mountains with 30 km downhill to start with. When charging to 100% regenerative braking would not be available. Would this reducing the braking potential of the car. Or would it be better to charge to 80% ? And arrive with 100 % down hill anyway with the regen. Probably the last.

side note: just went over the owner manual of the Panamera. In sport mode it charges the battery but maximum to 80% for two reasons. After 80% it is less effective but also to keep battery free for regenerative braking. Completely different system of course and lot less powerful regen braking compared to the Taycan.

And for the 270 kw regen : this are only peak moments I presume. Unless driving continuously down hill on a really steep slope.

It won't recuperate 20% unless you are sliding down Everest My experience of going downhill with heater broken (i.e. nothing to absorb energy), it simply switched off regen and it was a very disconcerting feeling - it would still brake but differently. When the heater was working, it would "regen" even on 100%, but I think it was putting the excess energy into the heater.

 

[McgR]

It won't recuperate 20% unless you are sliding down Everest My experience of going downhill with heater broken (i.e. nothing to absorb energy), it simply switched off regen and it was a very disconcerting feeling - it would still brake but differently. When the heater was working, it would "regen" even on 100%, but I think it was putting the excess energy into the heater.

The 80 % was for the 17 kWh Panamera battery not for Taycan.

Driving down hill can generate quite some electricity in my experience.

I haven’t driven the Panamera in the mountains yet but I did with my former X5 45e and after 30 km down hill it regenrated from 50 to almost 100%. This would be around 10 kWh so for the Taycan would only be 10-12 % SoC.

I have actually seen an increase of 10% in SoC driving down the Gross glockner road in max regen setting in the Taycan.

Driving down hill in the winter is different indeed because of the heating needed. Last winter I arrived with 96% downhill 30 Km, started with 100%, minus 5 degrees outside.

I have also seen negative consumption once driving down the Malloya pass to lake Como. I think this was more than 1 km hight difference. It can charge quite a lot

 

[DougFrisk]

I read that Taycans can regen as much as 290kW. If the battery isn't preconditioned and warm, why is this power level not damaging it?

Can regen up to 290, doesn't always regen at 290 kW. If you look at the power meter on the dash, you can see the limits displayed there graphically. If you use an ODB dongle and the car scanner app you can see the maximums numerically. If the battery is very cold or very near full charge you can see the reduction in maximum regenerative braking.

As for the heater, it draws 10 kW. It's not doing much to absorb power during braking.

 

[Jonathan S.]

It won't recuperate 20% unless you are sliding down Everest [...]

I get about 8% from driving down ~4,700 feet (or 1,433m for those who do not measure in Freedom Units).
So perhaps some mountain passes in the Alps could reg 20% on a summer drive?
Definitely an unusual situation though.
Plus the battery would be depleted below 80% from driving up first!

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