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Like, on paper they can do 250 kW but you never get more than 100 when actually charging it etc Yeah this is one area where there's a lot of deceptive marketin

by NickM 4y ago

Like, on paper they can do 250 kW but you never get more than 100 when actually charging it etc Yeah this is one area where there's a lot of deceptive marketing. For example the Kia EV6 specs list a max fast charging rate of 350 kW but what that actually means is that you need a 350 kW charging station to reach the car's actual max charging speed of 240 kW (or 180 kW, depending on the battery options). Granted, that is still nice and fast, and the EV6 is a great car, but it's really frustrating how hard it is to compare charge speed from different manufacturers.

abledon 4y ago
> For example the Kia EV6 specs list a max fast charging rate of 350 kW but what that actually means is that you need a 350 kW charging station to reach the car's actual max charging speed of 240 kW (or 180 kW, depending on the battery options). Wow that is the scummiest thing
giobox 4y ago
How is this deceptive? Anyone who has ever charged a phone is probably familiar with the concept that a higher wattage charger provides faster charging speeds - electric cars are no different. Higher power chargers charge faster is not some secret. The car simply states the fastest DC connection it supports - 350kw. It works with any charger up to this wattage, just like my laptop charges from any USB-C source up to 100w - was I missold my laptop too because if I use a 50w charger it only charges at 50w? EVs must charge from a huge range of different wattage chargers - I regularly switch between 7kw, 11kw, 50kw and 250 depending on the spec of the power source. The power you get is determined entirely by the DC plug you use (and to some degree state of charge, but lets not complicate this further...) - the car has no bearing on this beyond supporting up to 350kw in this example. The car can't magically make a 50kw charger output 350kw, as nice as this might be.
- jefftk 4y ago
  The specs say: [1] DC Fast Charge Time (10-80% @ 350 kW via Electric Vehicle Supply Equipment) Level 3 Charger: Approx. 18 min. and Drive Battery Energy: 77.4 kWh The battery is 77.4 kWh. This implies the battery is charging at 180kW. If it were taking in the full 350kW and losing 170kW as heat that would be one (inefficient and dangerous) thing, but it doesn't sound like it actually draws 350kW? For comparison, they say 73min for charging at 50kW, which implies the battery is charging at 45kW. If we figure that same 10% loss, then to charge at 180kW it's probably drawing 200kW from the charger. [1] https://www.kia.com/us/en/ev6/specs https://www.kia.com/us/en/ev6/specs [2] 70% * 77.4 kWh * (60min / 1h) / 18 min = 181 kW
  - giobox 4y ago
    As battery charges its pretty common to taper the charge rate to improve health of the battery. To my knowledge, no EV today will sit at 350kw for the full 10 to 80 percent even if it can draw this. You still get faster charge times as the full draw can usually happen at close to empty, but charge rate will taper as battery fills. 181kw average is still pretty great - there are many EVs on sale that still max draw at 50 (looking at you VW...).
    - jefftk 4y ago
      If the peak current draw were 350kW then I'd agree the specs were fine. I'd thought they were advertising a 10% to 80% charge because that's the period over which they can charge at max speed? Looking now, it seems like they start tapering at 50%, and it's peak draw is 235kW? https://www.arenaev.com/kia_ev6_crowned_the_best_charging_ev_in_the_latest_p3_charge_index-news-495.php https://www.arenaev.com/kia_ev6_crowned_the_best_charging_ev... (I agree this is very good, but it's still wrong to quote 350kW if they never draw this much.)
- freejazz 4y ago
  "Anyone who has ever charged a phone is probably familiar with the concept that a higher wattage" I assure you that my mother has no idea what a watt is.
tshaddox 4y ago
> For example the Kia EV6 specs list a max fast charging rate of 350 kW but what that actually means is that you need a 350 kW charging station to reach the car's actual max charging speed of 240 kW > it's really frustrating how hard it is to compare charge speed from different manufacturers Is the discrepancy just the inefficiency (i.e. waste heat) of the charging circuitry and/or battery chemistry? And if so, do different EV battery+charger systems have significantly different efficiencies? I would have expected that the consumer-facing spec is always the power taken from the grid, that there is always some inefficiency (you can draw less energy from the batteries than came out of the grid), and that the level of efficiency would be roughly similar across all cars. If that were the case, it wouldn't be much of a problem to compare charging rates across cars. But perhaps one or more of my expectations are wrong. Oh, and EVs presumably vary wildly in their "fuel economy" (miles per kilowatt-hour or whatever unit EV folks use), so even a "fair" comparison of charging rate presumably wouldn't paint the entire picture.
- NickM 4y ago
  Is the discrepancy just the inefficiency (i.e. waste heat) of the charging circuitry and/or battery chemistry? I'm not positive on the specifics but I believe it has more to do with the combination of supported voltages/amperages offered by different chargers. i.e. a "350 kW capable" charger in practice means it can do 800V charging, which other chargers of lower kW ratings typically can't do, and the EV6 requires 800V to reach its max charge speed but can't actually handle a high enough amperage to get to 350 kW. Like I said though, I might be confused on some of the details there, but I'm fairly positive it's not just waste heat...dissipating 110kW of waste heat would require some pretty insane cooling hardware. Oh, and EVs presumably vary wildly in their "fuel economy" (miles per kilowatt-hour or whatever unit EV folks use), so even a "fair" comparison of charging rate presumably wouldn't paint the entire picture. This is indeed a good point. A more relevant measure of charging speed would be something like "miles per hour at EPA rated efficiency", though even that gets messy since most cars don't charge at a linear speed. And I haven't seen any car manufacturers use this metric other than Tesla, who like to brag about their supercharger stations exceeding 1,000 MPH of charging speed (though only the newest stations can just barely do that, for very short durations, and only on certain car models). "Time from 20%-80% charge" would also be a better metric, due to non-linear charging speed curves, but I haven't seen that one used much either.

by NickM 4y ago

abledon 4y ago

giobox 4y ago

How is this deceptive? Anyone who has ever charged a phone is probably familiar with the concept that a higher wattage charger provides faster charging speeds - electric cars are no different. Higher power chargers charge faster is not some secret. The car simply states the fastest DC connection it supports - 350kw. It works with any charger up to this wattage, just like my laptop charges from any USB-C source up to 100w - was I missold my laptop too because if I use a 50w charger it only charges at 50w? EVs must charge from a huge range of different wattage chargers - I regularly switch between 7kw, 11kw, 50kw and 250 depending on the spec of the power source. The power you get is determined entirely by the DC plug you use (and to some degree state of charge, but lets not complicate this further...) - the car has no bearing on this beyond supporting up to 350kw in this example. The car can't magically make a 50kw charger output 350kw, as nice as this might be.

jefftk 4y ago
The specs say: [1] DC Fast Charge Time (10-80% @ 350 kW via Electric Vehicle Supply Equipment) Level 3 Charger: Approx. 18 min. and Drive Battery Energy: 77.4 kWh The battery is 77.4 kWh. This implies the battery is charging at 180kW. If it were taking in the full 350kW and losing 170kW as heat that would be one (inefficient and dangerous) thing, but it doesn't sound like it actually draws 350kW? For comparison, they say 73min for charging at 50kW, which implies the battery is charging at 45kW. If we figure that same 10% loss, then to charge at 180kW it's probably drawing 200kW from the charger. [1] https://www.kia.com/us/en/ev6/specs https://www.kia.com/us/en/ev6/specs [2] 70% * 77.4 kWh * (60min / 1h) / 18 min = 181 kW
- giobox 4y ago
  As battery charges its pretty common to taper the charge rate to improve health of the battery. To my knowledge, no EV today will sit at 350kw for the full 10 to 80 percent even if it can draw this. You still get faster charge times as the full draw can usually happen at close to empty, but charge rate will taper as battery fills. 181kw average is still pretty great - there are many EVs on sale that still max draw at 50 (looking at you VW...).
  - jefftk 4y ago
    If the peak current draw were 350kW then I'd agree the specs were fine. I'd thought they were advertising a 10% to 80% charge because that's the period over which they can charge at max speed? Looking now, it seems like they start tapering at 50%, and it's peak draw is 235kW? https://www.arenaev.com/kia_ev6_crowned_the_best_charging_ev_in_the_latest_p3_charge_index-news-495.php https://www.arenaev.com/kia_ev6_crowned_the_best_charging_ev... (I agree this is very good, but it's still wrong to quote 350kW if they never draw this much.)
freejazz 4y ago
"Anyone who has ever charged a phone is probably familiar with the concept that a higher wattage" I assure you that my mother has no idea what a watt is.

tshaddox 4y ago

> For example the Kia EV6 specs list a max fast charging rate of 350 kW but what that actually means is that you need a 350 kW charging station to reach the car's actual max charging speed of 240 kW > it's really frustrating how hard it is to compare charge speed from different manufacturers Is the discrepancy just the inefficiency (i.e. waste heat) of the charging circuitry and/or battery chemistry? And if so, do different EV battery+charger systems have significantly different efficiencies? I would have expected that the consumer-facing spec is always the power taken from the grid, that there is always some inefficiency (you can draw less energy from the batteries than came out of the grid), and that the level of efficiency would be roughly similar across all cars. If that were the case, it wouldn't be much of a problem to compare charging rates across cars. But perhaps one or more of my expectations are wrong. Oh, and EVs presumably vary wildly in their "fuel economy" (miles per kilowatt-hour or whatever unit EV folks use), so even a "fair" comparison of charging rate presumably wouldn't paint the entire picture.

NickM 4y ago
Is the discrepancy just the inefficiency (i.e. waste heat) of the charging circuitry and/or battery chemistry? I'm not positive on the specifics but I believe it has more to do with the combination of supported voltages/amperages offered by different chargers. i.e. a "350 kW capable" charger in practice means it can do 800V charging, which other chargers of lower kW ratings typically can't do, and the EV6 requires 800V to reach its max charge speed but can't actually handle a high enough amperage to get to 350 kW. Like I said though, I might be confused on some of the details there, but I'm fairly positive it's not just waste heat...dissipating 110kW of waste heat would require some pretty insane cooling hardware. Oh, and EVs presumably vary wildly in their "fuel economy" (miles per kilowatt-hour or whatever unit EV folks use), so even a "fair" comparison of charging rate presumably wouldn't paint the entire picture. This is indeed a good point. A more relevant measure of charging speed would be something like "miles per hour at EPA rated efficiency", though even that gets messy since most cars don't charge at a linear speed. And I haven't seen any car manufacturers use this metric other than Tesla, who like to brag about their supercharger stations exceeding 1,000 MPH of charging speed (though only the newest stations can just barely do that, for very short durations, and only on certain car models). "Time from 20%-80% charge" would also be a better metric, due to non-linear charging speed curves, but I haven't seen that one used much either.