Battery Degradation taken into account in charging algos?

[C20916]

I know Tesla and Elon say you should only charge your battery to 90% each night unless you're going on a trip then charge it to 100% because it's better for the battery, and when you charge to 100% the braking regeneration doesn't kick in until you get to 90%.

I bought a used 2016 90D, which has experienced battery degradation. I only get ~272 miles on a full charge, instead of the full 294 miles. I've noticed when I go on a trip and charge the battery full and get my 272 miles, that within 5 -10 miles of range being used to where I'm around 265-268 miles of range left, the braking regeneration is active. Which 90% of the full 295 mile range is 265 miles.

So my question is, if my battery has degraded pretty much to about 90% of it's original range, am I hurting the battery at all or causing it to degrade faster if I charge it to approx 265 miles every night, instead of leaving it on the Daily charging setting which gets me ~242 miles of range? Charging to 265 miles still has regeneration kick in right away.

 

[Tam]

...am I hurting the battery...

Extreme 0% and 100% are not good for your battery.

So setting yours at 90% is fine as instructed on the charging menu.

I would go with the charging menu and set it at 90% rather than set it at "miles" unit.

90% can mean different "miles" at different times.

So, setting at 90% is the goal, not "miles".

However, if you need to be on a road trip, then you should go ahead and set what you need: 90% to 100% as needed.

That means if you need to plan whether to

1) charge to 100% and arrive at 20% or
2) charge to 80% and arrive at 0%

Then choose 100% !

See:

The Rules of Model S Road Tripping

 

[C20916]

thanks for the response and I understand what you are saying, but if we use %, my question is more around the braking regen and when it should kick in. As you state 90% can mean different miles at different times, but it seems the braking regen calculation is set to be 90% of the full range with no degradation. So while yes my 90% is 242 miles, someone elses might be 250 miles, but I am guessing that everyone's braking regen kicks in at 265 miles, assuming 294 mile full capacity battery.

I remember reading that Elon said to charge only to 90% so that the car can take advantage of the braking regen, well if the regen kicks in at 265 miles regardless of what your 100% is, I didn't know if there was any harm in charging for me to say 95% everytime vs 90%?

 

[Tam]

...any harm in charging for me to say 95% everytime vs 90%?

You can look at your energy consumption on your instrument cluster for your present status of regen capability: Any restriction, partial or not.

The instrument cluster above shows that you can still have regen but not full regen and up to about -30 kW and definitely not -50 kW.

Of course, when your battery is all filled up, you can't put any more kW in there so the broken dashed yellow line would to to 0 kW mark.

As you start driving away, your battery starts to shed energy away and your 0kW mark would gradually move to negative territory until you would see no more broken dashed yellow line restriction.

So no regen is only true for the first few inches when you start driving away, but after a few feet of driving, there's room for a very small amount of kW to cram back in even though it's not perceptible by G-force.

Back to whether to charge at 95 or 90%:

Tesla charging menu does not encourage me to charge at 95%.

I would follow Tesla charging menu instruction and charge to 90% if more than 90% is not needed.

If charging 95% is needed then go ahead and do it.

But I would not just charge to 95% when there is no reason for it.

It sounds like you fine-tune the charging to 95% because you think that's full regen capability because you think that's how battery longevity works.

Remember, regen is also restricted in cold weather so even when you have only 60%, your instrument cluster can also clearly show the picture above.

That's also true in cold weather and your battery is at 30%, 20%, 10% and 0%...

So if you want to charge to the percentage that allows full regen in cold weather, would you want to charge it to the maximum of zero percent because, with that 0%, you can still get the picture above!

I would say no to charge your car according to regen status in the hope of its longevity.