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Slow charging (110V) impact on battery health ?

5_+JqckQttqck

Active Member
Apr 27, 2018
1,851
1,336
Toronto
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

Winter temps drain a significant amount of energy to warm the pack up. I tried to set the charge current to [email protected] AC with a target 90% charge when I leave in the morning... The car only got up to 270km (~55%, 35% short of the target charge after 10+ hours). Better to have more than less come winter.
 

arnis

Member
Apr 13, 2015
919
596
Estonia
There are even downsides for charging very slow (anything below 3.3kW is very slow).
If one full charge takes like 3 days. It is 72 hours of vehicle being online.
And there are some things that actually do wear out over time. Like coolant pump.
It's just running there. It has a lifetime. For usually like 50 000 hours.
Well, this is just 5 years.
Absolutely unnecessary wear and tear.

Also when vehicle is online for charging, it has a significant standby drain.
On some other vehicles, charging at normal speed (like 3-6kW) is 85% efficiency.
Charging on 120V lowers the efficiency down to 70%. Likely even less for Tesla as it has
much more awesome stuff inside.
 

Vinc

Member
Jul 7, 2018
427
265
Los Angeles
There are even downsides for charging very slow (anything below 3.3kW is very slow).
If one full charge takes like 3 days. It is 72 hours of vehicle being online.
And there are some things that actually do wear out over time. Like coolant pump.
It's just running there. It has a lifetime. For usually like 50 000 hours.
Well, this is just 5 years.
Absolutely unnecessary wear and tear.

Also when vehicle is online for charging, it has a significant standby drain.
On some other vehicles, charging at normal speed (like 3-6kW) is 85% efficiency.
Charging on 120V lowers the efficiency down to 70%. Likely even less for Tesla as it has
much more awesome stuff inside.

What about using level 2 charger but changing the settings in the car all the way down to 10A? My MS spends days in the garage without being driven, so my usual strategy is to just charge very slowly rather than charging faster just to have the battery sitting longer at 80% and drain by itself.

Now I am second guessing my approach...
 

TexasEV

Well-Known Member
Jun 5, 2013
7,640
8,464
Austin, TX
What about using level 2 charger but changing the settings in the car all the way down to 10A? My MS spends days in the garage without being driven, so my usual strategy is to just charge very slowly rather than charging faster just to have the battery sitting longer at 80% and drain by itself.

Now I am second guessing my approach...
Much less efficient charging that way. Set it at the highest amps your level 2 EVSE is capable of and keep the car plugged it. When the charge level drops by 3% the charging circuit will come back on. Let the battery management system manage the battery and just enjoy the car.
 
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Reactions: Vinc

arnis

Member
Apr 13, 2015
919
596
Estonia
What about using level 2 charger but changing the settings in the car all the way down to 10A? My MS spends days in the garage without being driven, so my usual strategy is to just charge very slowly rather than charging faster just to have the battery sitting longer at 80% and drain by itself.

Now I am second guessing my approach...
Reduce charge limit to 60-80%, set charging speed to some optimal level, for example 32A. No need to push it to the max.
My calculations estimate efficiency is "good" since charge rate of around 3.3kW. That is 16A at 230V. So no less than 16A.
120V is always inefficient. In addition to low current there is also considerable loss due to low voltage.
If charge rate is maxing out all the wiring offboard the vehicle, there might be a tiny extra loss there if it heats those conductors.
 
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Reactions: Vinc

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