BobB
Posts: 8
Joined: Fri Feb 05, 2021 5:24 am

Level 3 Charging

Wed Apr 21, 2021 7:33 am

I have access to a public Level 3 EVSE, fewer than 5 miles from my home. I’ve used it a few times but generally avoid it because I’ve read that Level 2 charging is better for the health of the battery than Level 3. Just wondering if some of you have any insight with regards to Level 3 charging. Should I be concerned about using it too much?

alohart
Posts: 2338
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Level 3 Charging

Wed Apr 21, 2021 2:37 pm

Because all i3's have the same maximum DC fast charging rate of 50 kW (usually ~45 kW in real world conditions), how much the battery cells are stressed depends on the battery pack size. As a result, DC fast charging is twice as stressful for a 60 Ah battery pack as for a 120 Ah battery pack.

The charge or discharge rate can be expressed as a function of the battery pack's total capacity. A 45 kW charge rate for a 22 kWh (60 Ah) battery pack would be ~2C but would be ~1C for a 120 Ah battery pack. I think that a 1C charging rate for a Li-ion battery cell isn't considered stressful. 2C is certainly more stressful, but it doesn't occur over the entire charge level range. Maybe others will provide more information.

Because 60 Ah battery packs seem much more susceptible to degradation than 94 Ah or 120 Ah packs, I limit DC fast charging for our 60 Ah battery pack. However, I would not worry about DC fast charging a 94 Ah or 120 Ah battery pack.
Aloha,
Art

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

BobB
Posts: 8
Joined: Fri Feb 05, 2021 5:24 am

Re: Level 3 Charging

Wed Apr 21, 2021 2:48 pm

Thanks Art. We have the 94 Ah battery. I was unaware of a relation between battery size and charging rate.

alohart
Posts: 2338
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Level 3 Charging

Thu Apr 22, 2021 11:00 am

BobB wrote:
Wed Apr 21, 2021 2:48 pm
I was unaware of a relation between battery size and charging rate.
This timely article provides much more detail.
Aloha,
Art

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

cdnji
Posts: 45
Joined: Mon Dec 12, 2016 2:07 pm
Location: Canada

Re: Level 3 Charging

Sat Apr 24, 2021 1:41 pm

Thanks for linking the article. After going through it, I'm confident now in using L3 EVSEs.
2017 i3Rex-Suite;Tech;Moonroof

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