DC Charge - Power/Voltage/Current don’t agree

[plastic]

Above us a snapshot from my current charge session at Evgo. I’m just trying to make sense of 199 amps at at least 356 v (to charge the battery - actual charge voltage should be higher) - which would be 70 kw - minus 1k for heater. I get there are losses, but 25kw of losses would have something glowing like the sun.

To be clear Im sure Im misunderstanding things somehow, but would like to figure out what i have wrong.

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[E90alex]

356V is the current battery pack voltage, not the charger output voltage.

Charging uses constant current at first and finishes with constant voltage closer to 100%.

So at 46.46kW at 200A the charger is outputting at about 232V

 

[plastic]

You need a voltage greater than the batteries current voltage to charge though, no? If the charger was only supplying 232V and the battery was at 356v it wouldn't be charging? I didn't think there was any cell splitting or dc/dc going on in the charging pathway.

 

[kltye]

You need a voltage greater than the batteries current voltage to charge though, no? If the charger was only supplying 232V and the battery was at 356v it wouldn't be charging? I didn't think there was any cell splitting or dc/dc going on in the charging pathway.

Yeah there's something wrong with the calculation there. The input voltage needs to be slightly higher than the pack voltage to charge - some Evgo stations even have a stage at the start of the charging process that says "Matching battery pack voltage". The system current should be what's going into the battery, and I've never seen the heater run at only 1kW (at least in my 2021). What did the Evgo station itself say the charging power was?

 

[plastic]

EVgo displayed from 46kW to 50kW ramping up slowly through through the charge. The OBD-II reading from carscanner matched the EVgo displayed reading.

The fordpass app shows 51kWh delivered for the same session. For an ER batter that maps to 51/.57 or 89kWh in size, so tracks at a 91kWh battery

The EVgo power numbers map to 41/.57 or 72kWh.. which is suspiciously matching the SR battery size. My car is an ER.

I'm even more confused now. It seems hard to believe that evgo is just giving away 25% more power than it's charging for....

 

[kltye]

EVgo displayed from 46kW to 50kW ramping up slowly through through the charge. The OBD-II reading from carscanner matched the EVgo displayed reading.

If the current displayed was more like 120 amps it would all make sense to me, it's just the 200 amo charge rate that confuses me.

Actually going from 20% to 80% on an extended range battery should be 91kwH * .6, or ~55kwH. 41kWh / 0.6 is 68kWh which seems more like a standard range battery (72 kWh). So I'm even mire confuse. Range estimator gives me ~230miles at 80% from mostly cold driving, so I doubt it's the wrong battery.

The slow ramp up from 46kW to 50kW is indicative that the DC charger was current limited (charging speed goes up as the pack voltage increases). I wonder if CarScanner is somehow using the wrong PIDs to figure out the current going into the battery pack.

As for your 20%-80% observation, that's indeed strange and I don't have any explanation for that - unless it wasn't actually a 20%-80% charge (not accusing you of anything, except that even the best of us makes mistakes, or the car is somehow lying to you about its SoC).

 

[plastic]

(sorry, edited my post with the fordpass info and change it a bit)
I don't actually think ford secretly swapped my battery somehow, feels more likely that the evgo station is somehow busted (but in my favor?)

 

[Mach-Lee]

(sorry, edited my post with the fordpass info and change it a bit)
I don't actually think ford secretly swapped my battery somehow, feels more likely that the evgo station is somehow busted (but in my favor?)

Yes busted and limited to only 200A.

 

[noway]

In DC charging the charge voltage and the battery voltage is "the same". There are no DCDC regulator between as 800V cars needs to have to charge on 400V stations, so no voltage conversion is or can be done. The increased voltage needed to charge the battery provided by the charger will also be reflected on the battery voltage while charging. There will be a small voltage drop from cables and contactors, but not high enough to be in the kW range, as it would quickly fry all cables if they was to produce kW of heat during charging.

 

[Teslaeata]

The problem is trying to make literal and logical sense of something about which you can’t know all the imponderables, best not to even try!!

Just luuuuuurrrrrrrrrve the ‘Stang!

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