Charging question

[Billionaireboy]

Ahoy Hoy - hope all are enjoying your long weekend.

I know you should not charge your Tesla up to 100% often. However, I have my charge limit at 100% but stop charging when I get to 85% to 90%.

I do this as I think (and I could be completely wrong here) that the charging slows down when it gets closer to the limit - so if I set the limit to 100% then I get faster charging around the 85% to 90% than if I set the charge limit to that.

Does my logic make sense?

Does anyone know or think this would cause a problem to the car?

 

[TheRealWatto]

This is like turning the thermostat up to 30 thinking it'll make the boiler heat up faster.

You should set it to what you want the battery to charge to.

 

[Lee Davis]

This is like turning the thermostat up to 30 thinking it'll make the boiler heat up faster.

You should set it to what you want the battery to charge to.

My wife does that. I used to fight it, now after 30 years I just roll with it.

 

[GeorgeSymonds]

I’m afraid your logic is wrong

Charging speed slows down as the battery fills up, not as it approaches the set charge limit. If you want to charge to 80%, just set it to 80%.

One exception for me, if I was supercharging and wanted say charge to 80% I’d probably set it to 85 or 90% if I needed to use the facilities, get some food, but only because I’d prefer to get back to the car with it charged to 82% than get an overstay charge. This just gives a few minutes time buffer. I wouldn’t advise setting it to 100% though as that would give maybe a 30 min buffer and that’s encouraging bad behaviour. I don’t really agree with it but I understand why people with, say, young kids trying to get food might do so. In that case it depends on how busy the superchargers are. Either way, tactical level setting at a supercharger to buy more time won’t change the charge rate.

As an aside, the later M3 SR+ and M3 RWD with LFP battery are happy to charge to 100%

 

[Regulo]

As an aside, and to hijack this thread, I never need to charge to 100% (LR3 li-ion battery) as I don't make long trips, but how often should I charge to 100%? I think it allows the battery management to correctly calibrate?

 

[Adopado]

As an aside, and to hijack this thread, I never need to charge to 100% (LR3 li-ion battery) as I don't make long trips, but how often should I charge to 100%? I think it allows the battery management to correctly calibrate?

I'm in a similar situation. The potential calibration mismatch is only really an issue if it affects your use of the car i.e. if the battery is reporting less range than you think it should and it's concerning you. It's up to you but going to 100% every few months isn't going to do any harm IMO. To get the calibration benefits you also need to go down to around 20% and let it sit for a couple of hours before charging again. I went for a long time without going 100% and then did a couple of 100% - 20% within about 10 days and it resulted in the car showing 10 more miles on a 2019 Fremont SR+ ... so not much more than about 5% ish ... so, measurable but not a huge deal.

 

[Billionaireboy]

This is like turning the thermostat up to 30 thinking it'll make the boiler heat up faster.

You should set it to what you want the battery to charge to.

I believe in Jeremy's theory

 

[Billionaireboy]

I’m afraid your logic is wrong

Charging speed slows down as the battery fills up, not as it approaches the set charge limit. If you want to charge to 80%, just set it to 80%.

One exception for me, if I was supercharging and wanted say charge to 80% I’d probably set it to 85 or 90% if I needed to use the facilities, get some food, but only because I’d prefer to get back to the car with it charged to 82% than get an overstay charge. This just gives a few minutes time buffer. I wouldn’t advise setting it to 100% though as that would give maybe a 30 min buffer and that’s encouraging bad behaviour. I don’t really agree with it but I understand why people with, say, young kids trying to get food might do so. In that case it depends on how busy the superchargers are. Either way, tactical level setting at a supercharger to buy more time won’t change the charge rate.

As an aside, the later M3 SR+ and M3 RWD with LFP battery are happy to charge to 100%

I currently do this at home when I know I need to get somewhere and leave at a certain time, I fully agree not to overstay (financially charged or otherwise) at a public or supercharger, so that others cant use them

 

[init6]

I know you should not charge your Tesla up to 100% often.

That's not correct if you have LFP batteries. From the manual:

If your vehicle is equipped with an LFP Battery, Tesla recommends that you keep your charge limit set to 100%, even for daily use, and that you also fully charge to 100% at least once per week. If Model 3 has been parked for longer than a week, Tesla recommends driving as you normally would and charge to 100% at your earliest convenience.

 

[prabhu]

That's not correct if you have LFP batteries. From the manual:

I'm hearing mixed views about this recommendation. People claim that all batteries would degrade faster when the cells hold maximum voltage so this 100% would only help Tesla display an accurate state of charge for the LFP chemistry and not the owners. I personally charge the car to 50-60% for daily use and 90% for road trips.

 

[init6]

I'm hearing mixed views about this recommendation. People claim that all batteries would degrade faster when the cells hold maximum voltage so this 100% would only help Tesla display an accurate state of charge for the LFP chemistry and not the owners. I personally charge the car to 50-60% for daily use and 90% for road trips.

What is your source for this? I'm going by what the manufacturer recommends in their manual.

 

[prabhu]

What is your source for this? I'm going by what the manufacturer recommends in their manual.

There are many, frankly, it is common knowledge that high voltage in cells increases resistance and degradation so even Apple laptops limit the full charge. Here's one example - Best charging behavior for LFP batteries - PushEVs

 

[init6]

There are many, frankly, it is common knowledge that high voltage in cells increases resistance and degradation so even Apple laptops limit the full charge. Here's one example - Best charging behavior for LFP batteries - PushEVs

The conclusion in that article is the same as Tesla's guidance:

Like many things in life, maybe the best is to compromise and reach a middle ground. You can usually charge your electric car with LFP battery up to 70 %, but then once a week charge it fully – before taking it for a ride (avoid let it stay on 100 % for a long period).

 

[prabhu]

The conclusion in that article is the same as Tesla's guidance:

Sure, end of the day it is the owner's wish regarding what they do with their car.

 

[init6]

Sure, end of the day it is the owner's wish regarding what they do with their car.

Agreed, but the article you referred to came to the same conclusion as the Tesla manual recommendation, so where are the mixed views that you previously referred to?

 

[MrT3]

What is your source for this? I'm going by what the manufacturer recommends in their manual.

Plenty of discussion and links to research here:

MASTER THREAD: 2021 Model 3 - Charge data, battery discussion etc

@AlanSubie4Life[/USER] The screenshot you asked for calcultaing the constant /battery size LR 2021 EU with 18" VIN 815xxx, Update 2020.44.25 E5D - old headlights Parked in a garage, Temp. 13°C; Mileage = 225 km WLTP 580 km - 148 Wh/km Rated on car @100% = 534 km (332 mi) , a 7% increase from...

teslamotorsclub.com

There certainly isn't evidence that LFP batteries don't suffer accelerated ageing when left in a high SoC. They haven't been out long enough, or enough research performed, to really understand but general opinion is they do suffer but not as much as other types of lithium batteries.

The vehicle manufacturer recommends what they do because they are confident that you won't age your battery to less than 70% after 8 years/100k miles keeping it at 100%, which is all they care about from a warranty point of view. But if you avoid 100% then your capacity could be nearer 90% rather than 70% after 8 years.

If you don't frequently charge to 100% then your estimated charge becomes inaccurate and you could go from 20% to 0% within a few minutes when driving - this is much worse for Tesla than a bit of accelerated ageing, hence the recommendation they provide.

 

[init6]

If you don't frequently charge to 100% then your estimated charge becomes inaccurate and you could go from 20% to 0% within a few minutes when driving - this is much worse for Tesla than a bit of accelerated ageing, hence the recommendation they provide.

That's also much worse for the driver