Home Charger power expectations/reporting

[Tooney]

Yes, @ciaranob, measure the voltage on your 100 amp circuit - but don't forget, it isn't the voltage that kills you, it's the amps...

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[daveo4EV]

when I discovered the North American Taycan's actually charge at 48 amps vs. being limited to 40 amps as Porsche incorrectly indicates on their spec's page for the Taycan - I posted pics to this thread…

https://www.taycanforum.com/forum/t...-charger-48-amps-not-max-9-6-kw-40-amps.1793/

as noted in my in car charging Pic's

• when charging at 40 amps (~9.6 kW raw power depending on voltage) - in car charging reports 8.68 kW
• when charging at 48 amps (~11 kw raw power depending on voltage) - in car charging reports 10.46 kW

so yeah - there is the "raw" power coming from the EVSE - and there is what is actually "hitting" the battery -which represents "losses" in the charging process - porsche seems to report battery kW - not "raw" Kw - which is why less than "raw" is in line with expectations.

 

[XLR82XS]

Garage temp 83F / 28.3C. In December. Ugh.

That's about my year round temp - love it. F the cold....

 

[madeyong]

so yeah - there is the "raw" power coming from the EVSE - and there is what is actually "hitting" the battery -which represents "losses" in the charging process - porsche seems to report battery kW - not "raw" Kw - which is why less than "raw" is in line with expectations.

Is it a charging loss due to physics/battery chemistry, etc., or is the difference because the car uses that delta (or part of it) that is not “hitting the battery” to power stuff during the charging process (like the AC charger itself, fans, etc.) rather than powering those items from the battery? I’ve always wondered that. I guess it’s somewhat all fungible but I’m curious if the car uses some of that grid power to actually power the car during the charging process and whether that comes off what the car shows as the charge rate on the center console in the car. For example, I believe I read that when you have preconditioning set to occur with a charging timer that the car uses grid power vs. battery power to precondition the car. I haven’t tested to see if the reported charge rate in the car drops during the preconditioning.

 

[ciaranob]

Is it a charging loss due to physics/battery chemistry, etc., or is the difference because the car uses that delta (or part of it) that is not “hitting the battery” to power stuff during the charging process (like the AC charger itself, fans, etc.) rather than powering those items from the battery? I’ve always wondered that. I guess it’s somewhat all fungible but I’m curious if the car uses some of that grid power to actually power the car during the charging process and whether that comes off what the car shows as the charge rate on the center console in the car. For example, I believe I read that when you have preconditioning set to occur with a charging timer that the car uses grid power vs. battery power to precondition the car. I haven’t tested to see if the reported charge rate in the car drops during the preconditioning.

I was of the assumption that most of these losses might be related to conductive capacity or efficiencies/inefficiencies of the raw materials in the EVSE and in the cables transporting the current to the car (including effectiveness of bounding insulation), the plug systems both on the cable and car and finally the delivery system/cabling in the car itself that direct current to the actual batteries. But indeed some draw may also be supporting active electronics in the car?

 

[daveo4EV]

Is it a charging loss due to physics/battery chemistry, etc., or is the difference because the car uses that delta (or part of it) that is not “hitting the battery” to power stuff during the charging process (like the AC charger itself, fans, etc.) rather than powering those items from the battery? I’ve always wondered that. I guess it’s somewhat all fungible but I’m curious if the car uses some of that grid power to actually power the car during the charging process and whether that comes off what the car shows as the charge rate on the center console in the car. For example, I believe I read that when you have preconditioning set to occur with a charging timer that the car uses grid power vs. battery power to precondition the car. I haven’t tested to see if the reported charge rate in the car drops during the preconditioning.

heat loss - AC to DC conversion, wire resistances, and power drain to run some computers managing the charging process - and charging itself is not 100% efficient - there is just “loss” between the power from the EVSE and reaching the battery - nothing too extraordinary - but 3-5% for AC/DC conversion is your opening bid and a bit more after that for other “things”.

 

[madeyong]

heat loss - AC to DC conversion, wire resistances, and power drain to run some computers managing the charging process - and charging itself is not 100% efficient - there is just “loss” between the power from the EVSE and reaching the battery - nothing too extraordinary - but 3-5% for AC/DC conversion is your opening bid and a bit more after that for other “things”.

AC to DC conversion makes sense. I forgot about that.

 

[Tooney]

"A closer look at minimizing AC charging losses: From the breaker to EV (Part 1)" Article Link
https://chargedevs.com/features/a-c...harging-losses-from-the-breaker-to-ev-part-1/

@madeyong

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