GMC HUMMER EV Forum | HummerChat.com banner
1 - 20 of 36 Posts

·
Registered
GMC Sierra, Bolt, Sky, Mach E
Joined
·
718 Posts
These dips in the curves are kind of interesting. OutOfSpecKyle saw similar dips on the Rivian and the EV6 and speculated it was some thermal limiting. But then the questions becomes, is it the vehicle that is thermal limiting, or the charger.

Has anyone started fast charges on the Hummer at different SoC levels, such as 40%, 50% or 60% to see what that curve looks like?

My Mach E does not have a curve that is directly related to SoC, it is a time based curve. It will give me 60 miles in the first 10 minutes whether I start at 10% or 50% SoC.
 

·
Registered
Volt, Polestar 2, R1T, Livewire One
Joined
·
946 Posts
These dips in the curves are kind of interesting. OutOfSpecKyle saw similar dips on the Rivian and the EV6 and speculated it was some thermal limiting. But then the questions becomes, is it the vehicle that is thermal limiting, or the charger.

Has anyone started fast charges on the Hummer at different SoC levels, such as 40%, 50% or 60% to see what that curve looks like?

My Mach E does not have a curve that is directly related to SoC, it is a time based curve. It will give me 60 miles in the first 10 minutes whether I start at 10% or 50% SoC.
I rarely stuck around at the truck to be able to observe charging speed at any particular time. It's too bad only chargepoint gives you a graph of the rate of charge after the session, and also too bad that they don't say what the SoC was either.
 

·
Registered
Joined
·
3,814 Posts
Discussion Starter · #6 ·
These dips in the curves are kind of interesting. OutOfSpecKyle saw similar dips on the Rivian and the EV6 and speculated it was some thermal limiting. But then the questions becomes, is it the vehicle that is thermal limiting, or the charger.

Has anyone started fast charges on the Hummer at different SoC levels, such as 40%, 50% or 60% to see what that curve looks like?

My Mach E does not have a curve that is directly related to SoC, it is a time based curve. It will give me 60 miles in the first 10 minutes whether I start at 10% or 50% SoC.
Tom from InsideEV has a Hummer now, doing charging and 70 mph range test today.
 

·
Registered
GMC Sierra, Bolt, Sky, Mach E
Joined
·
718 Posts
This kind of confirms my assumption that there is some thermal limiting going on. He is starting at a very high SoC, likely going to 100% to start the range test. He is over 100kw and from other tests at that SoC the rate is way down after a long charging session. A long session at high current is really heating up the battery, so it slows down later in the charge to keep the battery from over heating.

I am willing to bet that when he does the 0-100% charge after the range test, he will be scratching his head at the very different results.
 

·
Registered
Volt, Polestar 2, R1T, Livewire One
Joined
·
946 Posts
This kind of confirms my assumption that there is some thermal limiting going on. He is starting at a very high SoC, likely going to 100% to start the range test. He is over 100kw and from other tests at that SoC the rate is way down after a long charging session. A long session at high current is really heating up the battery, so it slows down later in the charge to keep the battery from over heating.

I am willing to bet that when he does the 0-100% charge after the range test, he will be scratching his head at the very different results.
I think you're probably right. Looked back on some of the photos I took of charger screens. I took this one obviously after it started throttling the rate of charge. Started at 9%, by 45% it dropped the rate down significantly like what TFL saw.
Watch Communication Device Telephony Gadget Portable communications device


I'd like to see Tom do a "charge until it throttles" repeated tests starting at 0,10,20,30,40,50%.
 

·
Registered
GMC Sierra, Bolt, Sky, Mach E
Joined
·
718 Posts
The other thing to consider is if the charger cable/connector are getting too hot. There is a temperature sensor in the CCS connector on the charger side. It might be interesting to stop the charge, after it throttles, then move to a different charger and start again to see what happens. That would prove if the thermal limit is on the charger side or the vehicle side.
 

·
Registered
Volt, Polestar 2, R1T, Livewire One
Joined
·
946 Posts
The other thing to consider is if the charger cable/connector are getting too hot. There is a temperature sensor in the CCS connector on the charger side. It might be interesting to stop the charge, after it throttles, then move to a different charger and start again to see what happens. That would prove if the thermal limit is on the charger side or the vehicle side.
Rivian is able to indicate to the user who is responsible for the slow down. I don't know why GM isn't doing it.
 

·
Registered
Joined
·
90 Posts
The other thing to consider is if the charger cable/connector are getting too hot. There is a temperature sensor in the CCS connector on the charger side. It might be interesting to stop the charge, after it throttles, then move to a different charger and start again to see what happens. That would prove if the thermal limit is on the charger side or the vehicle side.
The heat in the cable and head are relative to the amps, not the kW going through them. TFL changed the EVGo screen a couple of times to show the volts/amps when it was at 300 kW and it showed only about 400 amps. We've seen EVGO chargers handle a full 500 amps for extended times with Rivians and other high-kWh 400 volt-based EVs. I think this is something within the EV throttling. As others noted, TFL left the EV "on" and the cabin cooling "on". If you are running the EV and have the HVAC in cooling mode and the EV thermal management prioritizes the cabin cooling, it will starve the glycol chiller and not provide full pack cooling capacity. I've seen Ioniq 5's get hit with both that situation when charging in other videos.
 

·
Registered
2019 Chevy Volt, Voltech with 7.2 kW optional Charger
Joined
·
1,331 Posts
The heat in the cable and head are relative to the amps, not the kW going through them. TFL changed the EVGo screen a couple of times to show the volts/amps when it was at 300 kW and it showed only about 400 amps. We've seen EVGO chargers handle a full 500 amps for extended times with Rivians and other high-kWh 400 volt-based EVs. I think this is something within the EV throttling. As others noted, TFL left the EV "on" and the cabin cooling "on". If you are running the EV and have the HVAC in cooling mode and the EV thermal management prioritizes the cabin cooling, it will starve the glycol chiller and not provide full pack cooling capacity. I've seen Ioniq 5's get hit with both that situation when charging in other videos.
I actually emailed them about this. They claimed the car was off and they only ever pressed the Infotainment Radio button to power on the screens to see the kWs being put into the vehicle.
 

·
Registered
Joined
·
90 Posts
This kind of confirms my assumption that there is some thermal limiting going on. He is starting at a very high SoC, likely going to 100% to start the range test. He is over 100kw and from other tests at that SoC the rate is way down after a long charging session. A long session at high current is really heating up the battery, so it slows down later in the charge to keep the battery from over heating.

I am willing to bet that when he does the 0-100% charge after the range test, he will be scratching his head at the very different results.
I think I have found evidence that cell and pack voltage vs SOC while charging and after resting a bit may also be a factor about these variable and apparently unpredictable charging situations. I stumbled on a recent GM patent application for a charging control scheme that focuses on the cell voltages at various SOC's that can create dendrites. It creates multiple charging tables the BMS can use to regulate the charging amps, depending on the SOC at charge session start. Apparently, if you start from zero SOC at at a high charge rate, the cells hit that critical voltage earlier than if you start the charge session at higher SOC's. I have attached the charging curve chart included in the patent application that shows how the charge curves could vary depending on the SOC starting point. Note this is for a peak of 190-200 kW charging, which suggests the Lyriq pack was the example pack used.

I really need to dive into this further....it could be a gold mine of Ultium-based pack charging information. Stay tuned.
Slope Rectangle Font Parallel Plot
 
1 - 20 of 36 Posts
Top