EVMan
Posts: 309
Joined: Sat Feb 25, 2017 4:31 pm
Location: USA, CA

L2 fast vs slow charge ~ battery life

Sun Jan 12, 2020 9:49 pm

For all those, who charge mostly overnight and charging speed is not an issue
what is the better option to charge at L2 in USA.

Reduced 15Amp or 32 Amp ?
What is better for battery life ?

I know 220 volts is like 2% more efficient than charging at 110 Volts, so 22Volts wins over 110 volts

Also does it matter in Winters vs summers ?
2017 33KWH Rex
Model 3 Long Range
Solar ToU Plan

alohart
Posts: 1982
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: L2 fast vs slow charge ~ battery life

Mon Jan 13, 2020 1:02 pm

EVMan wrote:
Sun Jan 12, 2020 9:49 pm
For all those, who charge mostly overnight and charging speed is not an issue
what is the better option to charge at L2 in USA.

Reduced 15Amp or 32 Amp ?
What is better for battery life ?
Less current generally results in less battery cell degradation. 30.1 A is the peak current at 240 V according to Idaho National Laboratory i3 charging tests. That's a C/2 charging rate which isn't very intense, so the difference in battery cell life between 15 A and 30 A is probably insignificant. DC fast charging would be ~2C which would decrease battery cell life if this were the typical charging rate.
EVMan wrote:
Sun Jan 12, 2020 9:49 pm
Also does it matter in Winters vs summers ?
I doubt that battery cell life would be affected significantly based on using different charging power for winter vs. summer.
Last edited by alohart on Mon Jan 13, 2020 1:39 pm, edited 1 time in total.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

EVMan
Posts: 309
Joined: Sat Feb 25, 2017 4:31 pm
Location: USA, CA

Re: L2 fast vs slow charge ~ battery life

Mon Jan 13, 2020 1:21 pm

Thanks Art,
When i said Summers vs Winters, i was mainly referring to the temperature of the battery

As some videos of Tesla suggest, the car tries hard to increase battery temp , while charging, even if that means efficiency is lowered by generating heat.
Apparently Batteries like to be charged when warm and while DC charging, car makes effort to increase temp to 45C to 50C , when nearing full charge
Once charging is complete , it tries to cool the battery

So it may be in winters 30 Amp is desirable to keep them warm, and in summers 15 amp may just do the trick , to generate less eat
Its a one time setting , for a long term, so curious , even if one slightly better than others

I get 247 volts at my home. I have always seen less voltage in commercial street L2s
2017 33KWH Rex
Model 3 Long Range
Solar ToU Plan

jadnashuanh
Posts: 4837
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: L2 fast vs slow charge ~ battery life

Tue Jan 14, 2020 9:41 pm

Many commercial power systems use 208vac, so lower power is more common there versus at a home.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

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