Level 1/2/3 charger efficiency curves?

[daemonic3]

I tried doing some keyword searches and information is very scattered but I have not seen any tables or curves generated for the various efficiencies and levels of charging. Does anyone know of this being done? I have seen folks mention things anywhere from 85% to 95%, but I'm curious if there is a big difference between Level1, Level2 (at various amps), and Level3 (at various kW). NOTE: I am talking about the CHARGER inside the car, not the EVSE delivering the power.

My Grizzl-e will report kWh delivered, to one decimal place, so +/- 0.05kWh. The Fordpass app or car however, is very imprecise in reporting actual amount received. The charge log will give a percentage to nearest whole number which is already +/- 0.5%. And that is on a scale of 0-91kWh useable, so multiplying it out gives error of +/- 0.46kWh. Not good unless the charge session was large enough so the error is small. So far I'm getting between 88% and 94% using this imprecise method.

The best way would be to sit there and grab/log the OBD data during a live session. I would like to try it on my Level2 charger and grab 16A, 24A, 32A and 40A data points. I never grabbed Level1 but I can try that as well using the Ford EVSE. I have only DCFC once and don't see doing it any time soon so that set will be empty.

So my questions are:

1. Has anyone done this or seen it shared anywhere?
2. I have only logged OBD data when the car is on, anyone tried it while the car is off and charging? I am not sure if accessory power to the OBD reader is active in that mode. Otherwise I may have to find a way to subtract out the loss of running the instrument cluster.

I figure this might take an hour to collect, likely the data settles in only a few minutes during each charge. I just need to wait for a day when it is not record setting heat (114F today?!?!?) and I have a cooler garage.

And if anyone asks "why do you care?!?" well it just sounds like interesting data, that's why!

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[hawkeye3point1]

Easiest method I know using Carscanner data = energy-to-empty after charge minus e-to-e before charge / e delivered.

For Level 2 it is normally 90% +/- 2% regardless of current (24 - 45A). Level 3 somehow averages in the high 90s, opposite of what I would expect considering how much energy is expended to heat the pack to 90 deg. in NE climate.

 

[RickMachE]

And level 1 is around 85%.

 

[A-A-Ron]

Level 3 somehow averages in the high 90s, opposite of what I would expect considering how much energy is expended to heat the pack to 90 deg. in NE climate.

Even if it takes more energy for conditioning, it's a smaller percentage of the higher energy rate at Level 3 (If you're losing 1kw on a 9kw L2 charger, it's 11% but 4.5kw loss on a 150kw charger is only 3%). Also, with L1/2 - you're losing energy to the DC conversion process which isn't an issue with L3 charging.

ETA: My numbers are pulled out of the air, just there for the example

 

[ohmslaw]

I know where your coming from. Most converters I work with professionally have a peak efficiency load; would be nice to know what it is for the onboard charger. Always have more than enough time to charge overnight; would be nice to hit peak efficiency.

 

[daemonic3]

I know where your coming from. Most converters I work with professionally have a peak efficiency load; would be nice to know what it is for the onboard charger. Always have more than enough time to charge overnight; would be nice to hit peak efficiency.

Exactly! It would also be nice to know that since they sell a hard wired 48A L2 EVSE, that they designed for increased efficiency with load. I'd like the peace of mind that using my 40A setting has less waste than if I ratchet it down to 24A or something. Also it would help avoid having the worst loss (heat) at the highest loads.

I deal with these efficiency curves all the time in my work (regulators on IC's for phones, watches) and usually you have funny knees, bends, or inflection points in the curve because the regulator/converter switches modes at different load points. This will maybe help me find if the AC/DC converter has a single mode from 16A and upward or if it uses a mode-changing strategy.

 

[ohmslaw]

Even if it’s a difference of only like 1% between different currents that’s a large amount over the life of the vehicle. So let’s say it’s 90% efficient at 48amps and 90.5 at 30 amps. A 20kWh addition to the battery at 48amps would be 22.2 kWh and at 30amps that would be 21.9 kWh.

that would be a savings of $0.08 per day at my current electric rate of $0.26/kWh. Over the course of a year that’s $28; $280 over the 10 years we plan to have the vehicle. Seems stupid for such a negligible amount; but literally 0 effort to save money.

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