AC Charging Speed - What's more efficient?

[Whammy Bar]

Maybe there's no difference, but since this edible is working overtime, I had a thought...

Say I need to add 30kW to the truck to get back to my 90% charge target. Let's say I have 10 hours until I need to scram.

Am I better to let my level 2 charger rip at a full 48A and charge the truck in 3 hours? Or would I be more efficient charging at 24A for 6 hours.

I don't know what kind of losses happen on the internal charger, wasted heat, etc.

Anyone have any info on which is best? Same same? Any cool reading material?

Mickey, if you respond with some wisdom, thank in advance!

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[Maquis]

My opinion is that there are enough fixed losses in the charger and support systems in the truck that it makes charging at the highest rate most efficient. Some will disagree with me.

In the end, it’s probably not enough of a difference to worry about.

 

[queuewho]

I also read somewhere that with AC the higher the less losses. Some times being slower helps in some other ways though.

I lowered my charger down to 16A so I can more easily fit my charging into my excess solar generation. One option is, I could just quickly charge up using the grid and then have my excess solar sold back to offset it. Problem is there are some small fees per grid kwh used that get charged, and those fees aren't offset by kwh sold back.

Also, actively charging keeps the battery warm. If you have a trip coming up, it might be better to charger slower and have the truck be finishing up to your charge limit right when you plan to leave.

 

[RickLightning]

Many see the 32amp setting as a good compromise. Less heat. But haven't seen anyone scientifically measure it.

It would likely differ with different brand chargers too.

 

[Txxthie]

If you have a trip coming up, it might be better to charger slower and have the truck be finishing up to your charge limit right when you plan to leave.

Leave with a warm battery and that will improve efficiency of the truck. ABC (always be charging). I deep charge 1-2x a week to 90% (free public charger) and 1-4hrs each morning at home (30A) before departure depending upon my range needs.

 

[Whammy Bar]

Ok... So here's some prelim data.., however accurate, I don't know.

Emporia charger delivered 47.3kW last night to the truck. Ford Pass 4.2.5 when it doesn't crash reports the truck added 44kW.

The above charge was delivered at 48A, 50°F, clear sky with the moon in a waxing crescent phase, and the truck parked on a flat paved surface.

Will turn down (for what) to 24A and post back eventually.

 

[RickLightning]

Ok... So here's some prelim data.., however accurate, I don't know.

Emporia charger delivered 47.3kW last night to the truck. Ford Pass 4.2.5 when it doesn't crash reports the truck added 44kW.


The above charge was delivered at 48A. Will turn down (for what) to 24A and post back eventually.

The problem (in this illustration only) with FordPass is the inexact data.

That's a 6 - 8% loss if the FordPass number is accurate, due to no decimal places. That seems low.

 

[Heliian]

I added 74kwh(57%) of battery power with 86kwh of power from the charger. - 10degC though so power used for bms and my morning departure with a nice warm truck.

 

[Zprime29]

On the flip side of winter, do things change when it's over 100F outside?

 

[Whammy Bar]

Got some more info, this time at 24A charge rate.

Delivered 48.22kW via Emporia to a reported 42kW received by the truck.

---

@48A - 93% of each kW made it to the truck
@24A - 87.1% of each kW made it to the truck

I'll try and rerun these scenarios a few times to see how it averages out. Currently I'm plugging in when in the ~55ish % range wise, and letting it charge back up to 90%

 

[Pioneer74]

On the flip side of winter, do things change when it's over 100F outside?

The truck will then consume power to run the cooling circuit and fans.

Around 60 to 80 degrees is the sweet spot.

 

[RickLightning]

Got some more info, this time at 24A charge rate.

Delivered 48.22kW via Emporia to a reported 42kW received by the truck.

---

@48A - 93% of each kW made it to the truck
@24A - 87.1% of each kW made it to the truck

I'll try and rerun these scenarios a few times to see how it averages out. Currently I'm plugging in when in the ~55ish % range wise, and letting it charge back up to 90%

If you're not starting each test with the battery at the same temperature, AND with the vehicle at the same SOC< these numbers aren't very useful.

Also, if you want to play with math:

42/48.22 -1 = 12.9% loss
41.46/48.22 - 1 = 14% loss
42.44/48.22 - 1 = 12% loss

If you plug in an OBD reader, you'll find out that the displayed number is rounded/truncated (haven't played enough to care). You'll also can see exactly the amount of kW that the truck takes.

My point is that if you acknowledge a 12 - 14% loss (i.e. 2 point swing) on this, and you do the same on the 48amp, you might be comparing a 12% loss to a 9% loss, and if you're at a different state of charge and/or battery temp, then they may in fact be the same.

In reality, a cold battery has to warm up to charge faster, and the 48amp will warm it faster.

 

[Whammy Bar]

If you're not starting each test with the battery at the same temperature, AND with the vehicle at the same SOC< these numbers aren't very useful.

Also, if you want to play with math:

42/48.22 -1 = 12.9% loss
41.46/48.22 - 1 = 14% loss
42.44/48.22 - 1 = 12% loss

If you plug in an OBD reader, you'll find out that the displayed number is rounded/truncated (haven't played enough to care). You'll also can see exactly the amount of kW that the truck takes.

My point is that if you acknowledge a 12 - 14% loss (i.e. 2 point swing) on this, and you do the same on the 48amp, you might be comparing a 12% loss to a 9% loss, and if you're at a different state of charge and/or battery temp, then they may in fact be the same.

In reality, a cold battery has to warm up to charge faster, and the 48amp will warm it faster.

Temp is pretty constant at around 50F here in SoCal.
Truck has sat for at least 4 hours prior to charging being started.
I wasn't aware of any charging curve differences when AC Charging, regardless if the battery is at 10% or 90%.

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