Chevy Bolt EV Forum banner

1 - 20 of 28 Posts

·
Registered
Joined
·
197 Posts
Discussion Starter #1
Seems that different EVgo "50 kW" charging stations charge at different actual rates.


Recent stop: Charged form 20% to 60%, got 37 kW charging rate overall. Ambient temperature 100F. Charging station displayed around 370V and 99A.



Earlier stop (different charging stations): Charged from 25% to 50%, got 44 kW charging rate overall. Ambient temperature 100F. Had to restart charging due to error conditions during charging (heat related?).



Based on https://www.chevybolt.org/forum/82-charging-batteries/14002-dc-fast-charging-performance.html , it looks like the more recently used charging station was 100A, while the earlier used one was 125A. But the EVgo app lists both of them the same as "50 kW".
 

·
Registered
Joined
·
227 Posts
Theoretically the 100A stations could pump out 50 kW, but in reality no EV can charge that fast on a 100A unit.
It's the reason that DCFC should be listed in amps, not kW. The actual kW power is a function of the amps, which is fixed, and the current battery voltage, which is variable but never tops out any higher that 400 volts. So simple math shows that 100A x 400V = 40 kW, which is the highest realistic power for an 100A station. Of course taper will mitigate that too.

In general the battery is in the 360V ballpark in the heart of the charging cycle. That's the voltage that generally will maximize your power. You can see it in the instantaneous charge rates:

360V * 100A = 36 kW
360V * 125A = 45 kW
360V * 150A = 54 kW

The Bolt accept max power at 150A. So that's why when plugged into a 175 kW (350A) DCFC, it tops out in that 54-56 kW ballpark as 360V or so is the highest voltage that allows for maximum current before tapering.

Just remember that the nominal voltage of CCS1 is 500V and 500V batteries are not in any production EV. So the 175 kW stations are 350A @ 500V while the 350 kW stations are 350A @ 1000V. Using 360V or so as your multiplier gives better numbers. BTW a 125A DCFC should actually be a 62.5 kW station using the standard nomenclature. This is what causes the confusion between the 100A and 150A stations, which are both labeled at 50 kW.

ga2500ev
 

·
Registered
Joined
·
227 Posts
So where do we look to tell what the amperage is on these things?
It's usually listed on the unit. Here's an EVGo sample:



Note the maximum amperage in the output section. The problem is that since plugshare and the provider sites and apps rarely list the actual amperage, one generally has to read the label when at the station.

ga2500ev
 

·
Registered
Joined
·
329 Posts
Note the maximum amperage in the output section. The problem is that since plugshare and the provider sites and apps rarely list the actual amperage, one generally has to read the label when at the station.

ga2500ev
Very occasionally, someone will update PlugShare with the current rating of the station. I encourage everyone to do the same when you use these. I wish PlugShare had a specific place to enter it, but you can either put it in a comment or in the general description.
 

·
Super Moderator
Joined
·
2,028 Posts
Honestly, it's a fraud that the 100A stations are labeled as "50 kW". There is not a single EV out there that can charge anywhere close to 50 kW on one of those 100A stations. At least with the 125A stations you can get really close (the Bolt can hit 47 or 48 kW I believe).
 

·
Registered
Joined
·
329 Posts
The voltage and amps are usually displayed on the EVgo screen as you are charging. I assume other charge stations (Chargepoint, EA, etc) are the same.
This leads to confusion, as many people are unaware of their cars' taper profiles. I've seem people complain about only getting 67A from a station (it must be broken!) when their Bolt was at 75% SoC.
 

·
Registered
Joined
·
227 Posts
The voltage and amps are usually displayed on the EVgo screen as you are charging. I assume other charge stations (Chargepoint, EA, etc) are the same.
Those numbers are the actual charging power, not the maximum charging power. As the OP stated, both 50 kW (100 amp) and 62.5 kW (125 amp) DCFC are often listed at 50 kW stations. The charging screen technically doesn't give any information about the maximum capability of the station. I think the question is leading to "If I see two 50 kW stations, is there any way to tell without plugging in which one will charge my EV faster?" The label will do that. The screen will not.

ga2500ev
 

·
Registered
Joined
·
227 Posts
Honestly, it's a fraud that the 100A stations are labeled as "50 kW". There is not a single EV out there that can charge anywhere close to 50 kW on one of those 100A stations. At least with the 125A stations you can get really close (the Bolt can hit 47 or 48 kW I believe).
Agreed. The power is quite variable. However, the maximum amperage is fixed. It's clear when there is a 100A DCFC and a 125A DCFC that the 125A DCFC will charge faster. It's one of the reasons I always list both when discussing DCFC. So a 25 kW station would be listed at 50 amps for example.

ga2500ev
 

·
Registered
Joined
·
488 Posts
Agreed. The power is quite variable. However, the maximum amperage is fixed. It's clear when there is a 100A DCFC and a 125A DCFC that the 125A DCFC will charge faster. It's one of the reasons I always list both when discussing DCFC. So a 25 kW station would be listed at 50 amps for example.

ga2500ev
I always try for an Electrify America station if I am under 50%. If over 50% but under 65% I try for either an EA 150 amp, or a 125 amp EVgo or Chargepoint because charging is at 110 amps in that zone.
If you have to use a 100 amp Between 50% and 65% a 100 amp station is only 10 amps lower so it is not too bad. And from 65% to 80% they charge at the same speed because you are past the taper points. Only time I would use a dealership charger is if I am over 80% and need to get at or near 100% to reach the next charging stop since they max out at 50 amps.

Keith

TL : DR Over 50% use whatever, not a big difference. Under 50% try for EA and settle for EVgo or Chargepoint 125 amp.
 

·
Registered
Joined
·
103 Posts
So the 175 kW stations are 350A @ 500V while the 350 kW stations are 350A @ 1000V.
This isn’t quite right.

The newer chargers that support over 50 kW typically can output up to 900 to 1000V, so 175 kW chargers are typically rated as peak rates of 350A and 1000V but at voltages above 500V their peak amperage output is lower than 350A because they have a peak power output of 150 kW or 175 kW.

The 350 kW chargers typically have peak rates of 400A or 500A and 900 to 1000V although their power output is limited to 350 kW. So, voltages below 500V they may be able to output up to 500A.
 

·
Registered
Joined
·
21 Posts
It's the reason that DCFC should be listed in amps, not kW. The actual kW power is a function of the amps, which is fixed, and the current battery voltage, which is variable but never tops out any higher that 400 volts. So simple math shows that 100A x 400V = 40 kW, which is the highest realistic power for an 100A station. Of course taper will mitigate that too.

In general the battery is in the 360V ballpark in the heart of the charging cycle. That's the voltage that generally will maximize your power. You can see it in the instantaneous charge rates:

360V * 100A = 36 kW
360V * 125A = 45 kW
360V * 150A = 54 kW

The Bolt accept max power at 150A. So that's why when plugged into a 175 kW (350A) DCFC, it tops out in that 54-56 kW ballpark as 360V or so is the highest voltage that allows for maximum current before tapering.

Just remember that the nominal voltage of CCS1 is 500V and 500V batteries are not in any production EV. So the 175 kW stations are 350A @ 500V while the 350 kW stations are 350A @ 1000V. Using 360V or so as your multiplier gives better numbers. BTW a 125A DCFC should actually be a 62.5 kW station using the standard nomenclature. This is what causes the confusion between the 100A and 150A stations, which are both labeled at 50 kW.

ga2500ev
Ahhhh, yes! I just sent a feedback to plugshare on this issue... Brand new Bolt, plugged into a '50kW' charger, was getting (max) 37kW. What the heck? Oh, obviously it pumps a max of 100A. Duh! I guess a little math is too hard to learn. Oh well, I will learn. Unfortunately, EVgo at that station was charging $.29/minute!! Yow!
 

·
Registered
Joined
·
126 Posts
EVNo charges $0.35 / minute in Florida - works out to almost 6x the cost of a kWh from home...gotta be desperate to use one, and then only for long enough to reach a less costly alternative
 
1 - 20 of 28 Posts
Top