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Draining close to empty

RVD98072

Member
Oct 9, 2017
214
90
Seattle, WA
Is it bad to run the battery down close to empty all the time?

On ICE, I'm used to driving until the red light is on for awhile and using an EV I usually drive until I'm down to <20 miles range left on the Tesla and <10 miles range in other EVs (e.g. Leaf, etc.).

Is it bad to run it down that low? I don't run it to empty but usually the car is complaining about low charge, etc.

On the other end, I charge up to 80% or 90% only and never up to 100%.
 

TexLaw

Member
Jan 29, 2017
484
441
Bellaire, TX
Are you charging at home? If so, there really isn't much sense in letting the battery run down. If you are not, I suppose there could be some convenience in running it down, but it isn't particularly healthy.

If I recall correctly, it's best for the battery pack health to keep it at or above 20% on the low end.
 
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Reactions: IdaX

Cowby

S E X C R
Jun 2, 2015
603
122
ATL, GA
If u plan to keep the car for a long time then battery life optimization is from 30-80%, otherwise drive it like you would ice cars.
 

AZ Desert Driver

Rare combination
Mar 12, 2016
1,335
715
Tucson AZ
It seems like the idea of draining came from the old NiMH operation and the user has not evolved to the more modern chemistry that does not have Memory.
Now, if I was in the market for a used car, how could I tell if the battery was abused? What price penalty should apply here?
 

RVD98072

Member
Oct 9, 2017
214
90
Seattle, WA
fwiw, i charge up to around 90% and then drive off immediately and it's always at 264 miles (I have a MX 100D). I haven't noticed any decline since I got the car (roughly 7000 miles in right now).

i charge at home sometimes but mostly charge out at urban chargers while i'm on the road.
 

IdaX

Member
Dec 27, 2016
429
526
Moscow, Idaho
You shouldn't feel bad about using your entire range if you're on a trip and need an aggressive leg to get to a charger or something. But as a routine matter of course, no need to get below 25% or so.
 

lymex2018

Member
Feb 4, 2018
132
146
China
So this shows how the battery operates on its TOP. Would its bottom look the same?
I'm not quite sure what this bottom mean. The full pack is the full pack energy when charged to 100%, but the BMS can estimated when not charge to full. On the other end, when draining the pack to 0%, then there will be zero.

However, another parameter to look at is the internal resistance, the smaller the better.
 

AZ Desert Driver

Rare combination
Mar 12, 2016
1,335
715
Tucson AZ
So if I understand the above....when shopping for a used Tesla, take the car to a charger and fill it to 100%. Note how many miles the full pack reflects. Compare that to what a new pack should be. Divide A by B and see how much degradation has happened. If that number is better than 90%, don't discount for abused battery. If the number is 70% - choose another car. At 80%, assume the car has been abused but not ruined and discount by How Much?
 

lymex2018

Member
Feb 4, 2018
132
146
China
So if I understand the above....when shopping for a used Tesla, take the car to a charger and fill it to 100%. Note how many miles the full pack reflects. Compare that to what a new pack should be. Divide A by B and see how much degradation has happened. If that number is better than 90%, don't discount for abused battery. If the number is 70% - choose another car. At 80%, assume the car has been abused but not ruined and discount by How Much?
Yes. And the "normal" value can be found here. You can select mileage or age to see of it is above the average or below.
 

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