Fisher99
Posts: 269
Joined: Sun May 12, 2019 6:24 pm

Charging Cycles

Tue Mar 24, 2020 4:45 pm

Can someone enlighten me as to how charging cycles are counted? Is charging from 0% (yes, I know we never actually get to 0%) to 100% the same as charging from 50% to 100% twice (i.e, both equal to one charging cycle)? Or is 0-100 one charging cycle and 50-100 twice equal to 2 charging cycles? I very seldom charge from anything lower than 20%-30% remaining battery. I see figures stating the number of possible charging cycles on a battery but am not sure what a charging cycle really is. Am I wasting my apparently limited number of charging cycles by not getting as close to 0% battery remaining before I charge?

Yeah, I'm sure that I could dig through old threads and find an answer to this question but nobody has posted for several days, and many of us are self-isolating at home, so I thought we could use some discussion... :D

eNate
Posts: 415
Joined: Mon Sep 09, 2019 5:33 pm

Re: Charging Cycles

Tue Mar 24, 2020 5:37 pm

You've got it.

Starting with an individual battery cell, a full charge-discharge cycle is 0 to 100 back to 0.

As you link multiple cells together it becomes conceptual, on the same basis.

The accepted wisdom with the i3 is three thirds or two halves, etc., are equivalent to a full cycle. And since most of us never get to zero or virtual zero, and a few of us don't always get to 100, we're all supposedly still on equal footing.
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Fisher99
Posts: 269
Joined: Sun May 12, 2019 6:24 pm

Re: Charging Cycles

Thu Mar 26, 2020 9:03 am

Interesting! Thanks for the explanation. There are times that I think I should be limiting charge to 80% but since I have no automatic way to do that and I'm too lazy to monitor it manually, I just plug it in and forget about it. In the winter time, particularly, I plug it in whenever I'm at home, even it it still has a reasonable amount of battery. In the summer though, I'm more likely to only charge it if it gets down below 50% and I'm done with the car for the day.

eNate
Posts: 415
Joined: Mon Sep 09, 2019 5:33 pm

Re: Charging Cycles

Thu Mar 26, 2020 9:30 am

The enemy of any battery is heat. Cells get hottest as they near full charge. This can be mitigated by not fully charging (i3 only charges to 94% on 60Ah models), charge tapering (i3 BMS can slow charging is warranted), and active cooling (check).

If you have the time to spare between drives, you can always select to charge at a reduced rate. I nearly always charge at 16A / 120v, not out of concern for battery health, but because it's what's available at work. That rate barely registers as a blip on the battery temperature readout.

I don't know what Level 2 rate begins to creep into "abusive" territory for the i3, but by all accounts I've read, the car does a good job taking care of itself, leaving not much to worry about.
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alohart
Posts: 2023
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Charging Cycles

Thu Mar 26, 2020 1:46 pm

Fisher99 wrote:
Thu Mar 26, 2020 9:03 am
There are times that I think I should be limiting charge to 80% but since I have no automatic way to do that and I'm too lazy to monitor it manually, I just plug it in and forget about it.
If I set an alarm on my iPhone for 1 hour before the estimated fully charged time displayed on our 2014 BEV's instrument panel and stop charging at the alarm time, the charge level will be ~90% displayed or ~85% actual for our 208 V 16 A EVSE. If I might need full range, I can relatively quickly charge the remaining 10% just prior to departure. That's good enough for me.
Aloha,
Art

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

Fisher99
Posts: 269
Joined: Sun May 12, 2019 6:24 pm

Re: Charging Cycles

Fri Mar 27, 2020 11:33 am

Never thought about checking the estimated completion time on the dash. Actually, didn't even know that it showed that info, as I've never really paid attention to the dash when I plug in. But that does sound like a reasonably workable option.

eNate
Posts: 415
Joined: Mon Sep 09, 2019 5:33 pm

Re: Charging Cycles

Fri Mar 27, 2020 1:12 pm

I installed a 20A Tork dial timer for this.

What's cool is it has two output legs: one is switched ON while the timer is running, and the other side is switched OFF.

So I can plug in to one receptacle and dial in the number of hours I want the car to charge, or or can plug in to the other receptacle and dial in the number of hours to delay charging.

The main reason I installed this is because I do most of my charging at work, so I like to leave home showing about 75% SOC. Anything above that, and the car will hit 100% before the end of my work day, which means I'm not maximizing my use of free (to me) electricity.
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Fisher99
Posts: 269
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Re: Charging Cycles

Fri Mar 27, 2020 2:15 pm

Do any of the current electric vehicle's take care of this automatically? Seems that the onboard charger/BMS should easily be able turn off charging at a preset percentage of charge.

eNate
Posts: 415
Joined: Mon Sep 09, 2019 5:33 pm

Re: Charging Cycles

Fri Mar 27, 2020 3:49 pm

I know for certain Kia does with the eNiro. I don't recall if it's preset to 80%, or if it's user adjustable, but 80% is a commonly discussed stop point.

I've read references to Tesla requiring the user to select a setting for charging to 100% when they need the extra range, otherwise it stops at a lower level. Whether it applies to specific models or provides a user adjustable stop point, I don't know.
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alohart
Posts: 2023
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Charging Cycles

Fri Mar 27, 2020 4:11 pm

eNate wrote:
Fri Mar 27, 2020 3:49 pm
I know for certain Kia does with the eNiro. I don't recall if it's preset to 80%, or if it's user adjustable, but 80% is a commonly discussed stop point.
Early Leafs had this capability as well. Not sure about current Leafs.
eNate wrote:
Fri Mar 27, 2020 3:49 pm
I've read references to Tesla requiring the user to select a setting for charging to 100% when they need the extra range, otherwise it stops at a lower level. Whether it applies to specific models or provides a user adjustable stop point, I don't know.
I believe that the Tesla charging UI allows the driver to set charging to stop at any charge level which is the way it should be.
Aloha,
Art

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

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