Mods, this is ID.4 specific so I posted here but feel free to move to the Charging forum if you think it's appropriate.
I've posted elsewhere that, at 120 volts, my BMW i3 charges about 20% more efficiently at 16 amps than it does on the stock 12 amp EVSE. I expected this to translate over to the ID.4.
Test summary: I didn't detect any difference in ID.4 charging efficiencies among the different Level 1 amperages. Increased efficiency of 13 to 21% became apparent when supplying these EVSEs with 240 volts.
I brought together all 3 Level 1 EVSEs I have and put them to the test:
- VW 10 amp dual 120 / 240 volt
- BMW 12 amp 120 volt (probably dual voltage but haven't tested it yet
- Duosida 16 amp 120 / 240 volt
My test was a bit basic: plug them in, let them charge for about 10 minutes, and record the SOC and time remaining data from Car Net (and from BMW Connected).
I then crunched the numbers and decided that a meaningful unit would be Percent Increase per Amp over 8 hours
. I usually charge my i3 at work for 8 hours, seems like a good overnight number, and boiling it down to "per amp" provides a good idea of what each amp of power gains on the car's State of Charge.
is how much total charge is gained over 8 hours.
For the BMW i3:
%/A -- [21.0%]
%/A -- [25.0%]
%/A -- [40.0%] (20% more efficient than 12 amp)
So you can clearly see an obvious benefit to charging the BMW at 16A.
When I plug the 16A unit in to 240v, this rate effectively remains the same but the voltage doubles. Another way of expressing it is (16A x 120v) + (16A x 120v) or equivalent to 32A @ 120v:
%/A** -- [80.0%]
Now for the ID.4:
%/A -- [12.5%]
%/A -- [14.5%]
%.A -- [19.5%]
%/A** -- [28.0%]
(13% more efficient than L1)
%/A** -- [48.0%]
(21% more efficient than L1)
A couple of notes.
I don't think the decrease from 10A to 12A is real or significant. This is likely a result of me running the test over only 10 minutes and using round numbers provided by the app (nearest % and 5 minute increments). I believe these are all within a margin or error and are effectively "the same."
If I have the time to run these over a longer period -- 8 hours, perhaps? -- I've have slightly more accurate results.
** The 20A and 32A numbers are the 10A EVSE and 16A EVSE plugged in to 240 volts
However I DO believe the increase in efficiency as we move to Level 2 on the ID.4.
Lastly, even though the BMW and VW %SOC are not directly comparable (the BMW's battery 28kWh usable, about 1/3 the capacity of the VW's 77 kWh), I'm puzzled why the %/A figures don't represent a 3x difference. I may have an error in how I calculated my numbers, since the BMW shows time to reach 100%, vs. the VW showing time to reach 80%. If I find an error I'll correct it but I'm confident the numbers inside each vehicle are reflective of relative charging efficiencies correctly.