Slow charging (110V) impact on battery health ?

[eggy]

Apologies, if this has been discussed before, but I couldn't find anything.

I was wondering, whether constantly charging a MS battery on a 110V outlet would have a negative impact on the health of the battery long term considering that the charging process and hence the stress on the battery lasts much longer (timewise) compared to charging on a 11kw/22kw-charging station or even at a supercharger.

 

[KarenRei]

Just the opposite. Slow charging leads to the longest longevity for batteries. Just be aware of how slow it is - remember that a simple hair dryer or mini space heater uses up nearly 100% of the capacity of a 120V 15A socket, and you're looking to charge a car off of it.

If your goal is maximal longevity:

* Get as large of a pack as you can afford
* Charge at as slow of a rate as you can
* Avoid supercharging to the extent that you can.
* Limit your charges, to try to cycle around the middle of your pack's charge range when you drive (aka, fill to 70% full, drive to 40% remaining)

That said, longevity is not proving to be a problem for most users. Tesla put a lot of work into battery management for this purpose (unlike Nissan, with the passively cooled battery "box" on the Leaf which often degrades badly in just a couple years).

 

[TexasEV]

Apologies, if this has been discussed before, but I couldn't find anything.

I was wondering, whether constantly charging a MS battery on a 110V outlet would have a negative impact on the health of the battery long term considering that the charging process and hence the stress on the battery lasts much longer (timewise) compared to charging on a 11kw/22kw-charging station or even at a supercharger.

Yes you are correct.

 

[dhrivnak]

Just the opposite. Slow charging leads to the longest longevity for batteries. Just be aware of how slow it is - remember that a simple hair dryer or mini space heater uses up nearly 100% of the capacity of a 120V 15A socket, and you're looking to charge a car off of it.

If your goal is maximal longevity:

* Get as large of a pack as you can afford
* Charge at as slow of a rate as you can
* Avoid supercharging to the extent that you can.
* Limit your charges, to try to cycle around the middle of your pack's charge range when you drive (aka, fill to 70% full, drive to 40% remaining)

That said, longevity is not proving to be a problem for most users. Tesla put a lot of work into battery management for this purpose (unlike Nissan, with the passively cooled battery "box" on the Leaf which often degrades badly in just a couple years).

While I agree with most of what you have said. the charging to 70% is a double edge sword as keeping the battery balanced is also important as your battery is only as strong as your WEAKEST brick. In the Roadster the balancing only happened above 82% and a number of owners have experienced much shorter range due to an unbalanced pack. So if you set the charge level to 70% I would charge at least to 90% once a month and leave it set for several hours.

 

[KarenRei]

While I agree with most of what you have said. the charging to 70% is a double edge sword as keeping the battery balanced is also important as your battery is only as strong as your WEAKEST brick. In the Roadster the balancing only happened above 82% and a number of owners have experienced much shorter range due to an unbalanced pack. So if you set the charge level to 70% I would charge at least to 90% once a month and leave it set for several hours.

Quite true, and I should have mentioned that. Li-ion SOC measurement is generally based on coulomb counting with periodic recalibration, and periodic equalization is important as well.

 

[HKRied]

I see knowledge here. I'm retired with a 90D. I have a 240 plug and typically charge to 80% (~240 mi) and run down to 100-125 mi every few days before plugging in. On a daily basis, it's unplugged more than it's plugged in. I don't put on a lot of miles and sometimes go days parked in the garage. Although, as the seasons change, I'll travel 1300 miles north/south and set it to 100% for the trip. Same for occasionally vacation travel. So here's the Question: Since I don't drive a lot daily, would it make sense to switch to the 110v adapter for normal day-to-day? I'd still probably charge every other day or so most of the time, 10 hours overnight at 4mi/hr for 40 miles. Feel free to tell me I'm in the weeds here. I know it's minutiae. But maybe I need to stretch my battery life so I get the FSD I paid for.

 

[brkaus]

Instead of 120v, I'd stay with 240v and set the amps way down.

 

[chipmunk]

You should know though, that charging more slowly is generally less efficient and results in more energy being spent on running the electronics that charge the car and maintain the temperature. It's something like 80% efficient, as opposed to 90% efficient on a decent amperage 220 volt circuit. Source

Also, I wonder if there is any impact on the longevity of the charger itself?

 

[KarenRei]

You should know though, that charging more slowly is generally less efficient and results in more energy being spent on running the electronics that charge the car and maintain the temperature. It's something like 80% efficient, as opposed to 90% efficient on a decent amperage 220 volt circuit. Source

That might be a bit distorting. The vehicle uses some power whether it's charging or not. Obviously the slower you charge, the more the percentage of the total power input will go to parasitic losses, but that's not the fault of charging - that's just due to how much time the parasitic losses are counted for.

As a general rule, slow charging is the most energy efficient manner. Without any parasitic losses accounted for (fans, climate control, etc), slow-charged li-ions can be over 99% efficient - but fast charged li-ions lose a lot to heat, often with sub-95% and sometimes sub-90% efficiency.

 

[chipmunk]

That might be a bit distorting. The vehicle uses some power whether it's charging or not. Obviously the slower you charge, the more the percentage of the total power input will go to parasitic losses, but that's not the fault of charging - that's just due to how much time the parasitic losses are counted for.

As a general rule, slow charging is the most energy efficient manner. Without any parasitic losses accounted for (fans, climate control, etc), slow-charged li-ions can be over 99% efficient - but fast charged li-ions lose a lot to heat, often with sub-95% and sometimes sub-90% efficiency.

I understand what you're saying, but parasitic loss can't account for all of that. People are seeing like a 20% variance. It would take a long time to lose that much charge in a car just sitting there unplugged and off.

 

[HKRied]

I'm new here and the response is disappointing (maybe just over my head). I'm a basic computer geek but know nothing of battery tech. I guess I'll stick with 220v.

 

[TexasEV]

I'm new here and the response is disappointing (maybe just over my head). I'm a basic computer geek but know nothing of battery tech. I guess I'll stick with 220v.

Actually make that 240V
Here's Tesla's recommended installation of the 240V 50A outlet:
https://www.tesla.com/sites/default/files/downloads/US/universalmobileconnector_nema_14-50.pdf

The only reason to even think about charging a Tesla at home using 120V is if installing a 50A circuit is cost prohibitive. And if that's the case, give serious thought if a Tesla is really for you.

 

[KarenRei]

Actually make that 240V
Here's Tesla's recommended installation of the 240V 50A outlet:
https://www.tesla.com/sites/default/files/downloads/US/universalmobileconnector_nema_14-50.pdf

The only reason to even think about charging a Tesla at home using 120V is if installing a 50A circuit is cost prohibitive. And if that's the case, give serious thought if a Tesla is really for you.

Now now, not everyone owns their own property and can make modifications. And for the record, it's perfectly reasonable to say 220V, 230V, or 240V. They're just nominal voltages anyway, the actual voltage often deviates significantly from that. And US voltages tend to run below their nominal. If I recall correctly, the actual US average is something like 117V/234V. You might be a couple volts over 120V if you're close to the pole, or even below 110 if you're far away with bad wiring. The high voltage split phase outlets are ostensibly double that of the single phase, but they can sometimes measure a bit less since the phases don't perfectly match up.

Where I am we're a nominal 230V. And usually hover around that mark. US split-phase voltages are in practice pretty similar.

That said, I agree with you that if they can, it would be advisable to install a higher power socket. But if you have the short-range variant Model 3, there's not much point to going over 30A, because the charger can't take more than that.

 

[TexasEV]

And for the record, it's perfectly reasonable to say 220V, 230V, or 240V. They're just nominal voltages anyway, the actual voltage often deviates significantly from that.

in the US it's not reasonable to say 220 or 230V. Nominal residential voltage has been 240V for at least 50 years.

 

[HKRied]

Instead of 120v, I'd stay with 240v and set the amps way down.

How do you the amps?

 

[JHWJR]

I understand what you're saying, but parasitic loss can't account for all of that. People are seeing like a 20% variance. It would take a long time to lose that much charge in a car just sitting there unplugged and off.

It seems that the chargers on the car take a certain amount of energy to operate. Your car gets what's left over. With 110v, there is not as much leftover as with 240v. Therefore, 240v is more efficient as a higher percentage of the current reaches the batteries. And the difference can be significant. But if 110v is all you got and all you are going to get, your biggest challenge will be getting enough in the battery to get you where you need to do, not the extra $2 perhaps that it takes to get a full charge.

 

[brkaus]

How do you the amps?

While you are at the location in question, bring up the charging screen on the center console.

Lower right corner of that screen shows amp settings. Just turn it down with the arrow.

 

[chipmunk]

It seems that the chargers on the car take a certain amount of energy to operate. Your car gets what's left over. With 110v, there is not as much leftover as with 240v. Therefore, 240v is more efficient as a higher percentage of the current reaches the batteries. And the difference can be significant. But if 110v is all you got and all you are going to get, your biggest challenge will be getting enough in the battery to get you where you need to do, not the extra $2 perhaps that it takes to get a full charge.

Absolute agree. I charge on 110v somewhat often, but all things considered I think 220v is preferable if available. Also, since the topic is longevity of the battery, you can afford to keep the battery at a lower state of charge knowing you can quickly top up when needed.

I'm guessing maintaining a lower SOC will extend the battery life more than charging slowly.

 

[Electriccarnut]

Actually make that 240V
Here's Tesla's recommended installation of the 240V 50A outlet:
https://www.tesla.com/sites/default/files/downloads/US/universalmobileconnector_nema_14-50.pdf

The only reason to even think about charging a Tesla at home using 120V is if installing a 50A circuit is cost prohibitive. And if that's the case, give serious thought if a Tesla is really for you.

There's another reason: I had solar installed this year and found my system was selling too much back to PG&E (at 3 cents a KWH) So I bought a Tesla. Mine's a salvage-rebuild and I saved a bunch of money!!, I don't have a supercharger near where I live and charging at 120V doesn't outstrip my solar. I have driven for free since May '18 and my PG&E bills have run about $8.00 a month (Tesla or not).

Love my car. So far it's been faultless.

 

[SSedan]

I would be interested in what the OP experienced but my gut says 120volts in NJ became a problem come winter.

Far as slow charging being good, we are talking a low power 120volt connection spread across 7104cells in an 85kwh battery and taking 3+ days to charge from zero. That is way slower than slow charging to the point where it is just silliness to suggest it is beneficial. About like driving 5mph instead of 35 when hypermiling...........
A 100D could be more than 4 days at 3mph, when you look at it like that it seems stupidly slow right?

Now the case of keeping load low enough for home solar is reasonable