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Discussion Starter · #1 ·
We recently got back from an ~3400 mile round trip from Metro Detroit to Fort Myers, Florida. Our route went through Nashville on the way down, and back up across West Virginia. Quite a bit of local driving in Fort Myers area.

Because of wanting to split things up to limit the amount of time in the truck every day, we took 5 days of driving to get down, and 4 to get back. We were able to stop for some day activities, but not as many as originally planned due to bad weather.


TL;DR for the trip:

-Charging was pretty much a non-issue. Overnight charges at hotels were good for less than 50% charge. Make sure you have enough charge at your hotel arrival to get to the next DCFC. At one hotel, one charger was broken, the other was in use. We left in the morning with quite a low charge level. Planning ahead by checking plugshare made us aware of a potential issue for one of the EA stations. Making sure to have enough charge to skip it worked out when we arrived and 2/4 stations were out of commission, and we would have been waiting in a line. Never had issues with unexpectedly slow charge rates. Every charge on a 350kW station was over 200kW at some point. A few were hit over 300kW but the conditions seemed to have to be perfect to hit it.

-We could reliably recover 150-175 miles of highway range with 30 minute stops. Optimizing for 30 minutes puts arrival somewhere between 10-15% and leaving with 65+. Taper starts to kick in above that, but isn’t painful until somewhere above 75%. Starting from 100% was rare, but comfortably gave us around 250 miles in cold weather before needing a charge. 275 might be a good number in good weather but the one time we could have hit it, I stopped early because of upcoming bad weather.

-Charger spacing still sucks in a lot of places. The wide range of fairly optimal charge rate, and just sheer amount of range the Hummer gets, made it a non-issue. We arrived anywhere from 3% to 44% at chargers. Most of the higher charge arrivals were due to staying longer than we needed at the station before, and having a planned activity where we plugged in.

-EV part of the truck was flawless. We had some non-ev issues crop up during the trip that the dealer is going to address.


I wanted to be able to provide a real detailed account of energy usage and charge times, but we had a lot of issues with being billed properly. One thing I didn’t account for was that turning off the vehicle resets the energy consumption page. I was going to try to rely on that for information as well and ended up losing some of it, so at some point I just stopped paying close attention to it.
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The very first leg of our trip was the longest distance before stopping for a charge. In other EVs we would typically have to go out of our way to stop at a previous station, but I wanted to take the chance of skipping that one entirely. It worked out. Traveling the speed limit in below freezing weather we went 242.8 miles on 191 kWh. The truck stated we arrived at the charger with 11% battery left.
Audio equipment Font Machine Electronic device Display device

Unfortunately, this was our first charging stop and we had both the truck and the charger bug out and stop updating charge status while we were eating dinner. This happened a couple more times during the trip and every time resulted in not being charged for the entire session(or in one case, at all). The charging sessions never got interrupted, but I really hope EA/GM fix whatever this issue is, because I'd really like EA to not go out of business from giving away free electricity. It was snowing when I got back to the truck and didn't think to snap a photo of the station itself, so have no idea how much charge we ended up getting here. We continued on to the hotel a short distance later and arrived with 66% charge. After fussing around with it a while, I was finally able to get it working. I had never seen a SemaConnect charger before so had no idea how to get it activated.
Over night, we had 75kWh delivered to the truck in ~13.5 hours. It was just enough time to hit 100% charge.

We skipped our original morning plan to go to the Cincinnati zoo because of the cold and wind, and headed out. Stopped at the EA station in Clarksville, IN for lunch. Getting here was a little strange and somewhat out of the way. In our original plan, we would have tried to skip this stop. 42%-92% over 1:04, 117kWh delivered.

After that we headed to the National Corvette Museum. I had never been there before, and having the charger available made it an obvious place to stop. My son really enjoyed all the cars there, highly recommend planning it as a stop if you are driving an EV through the area. There was an i3 just about to leave when we arrived. The first other EV we had seen at a charger on our trip so far.
Wheel Car Tire Sky Vehicle

We arrived with 44% charge, and left with 90% charge after 54 minutes, and 107kWh delivered. After that we continued on to Nashville where we stayed for two nights visiting family. I used my TeslaTap to charge up there on their Tesla UMC. First time trying to use it with the Hummer and it worked fine here.

Monday we headed to the US Space and Rocket center. We were there for about 2.5 hours, only added ~12 kWh in that time. With how big the battery in the Hummer is, decided that stopping at an L2 station for an activity is basically worthless.
Sky Wheel Car Tire Building

Left there and drove to the EA station in Alabaster AL. Originally had hoped to entirely skip fast charging that day. Probably could have if we drove slower, but in anticipation of maybe having charging issues at the hotel overnight, we opted not to take that chance. 22-58% in 19 minutes 12 seconds, 85kWh delivered. One of our quickest charges on the whole trip, just the time it took for bathroom breaks.
Sky Cloud Plant Tree Road surface


Stopped for dinner, the continued the drive to the hotel we were staying at in Montgomery, AL. Arrived at 30% charge. I opted to use the Tesla station instead of the J1772 since it was 40A vs 32A, and knew it wouldn't hit 100% charge before the next day anyway.
Weird looking cybertruck


I didn't make note of what charge level we left the next morning, it was too hectic because I changed our plan the last minute due to the forecast weather being all rain on the route down through Chipley and Tallahassee. I originally had hoped to stop at something outdoors but that wasn't going to happen. Instead, we drove across Alabama to the public Library in Leesburg GA. It would be our only non-350kW charge stop, as they had a 62.5/125kW station there. They let us hang out in the library and play with their toys while we waited for the charge. Whoever painted the lines obviously didn't anticipate an EV the size of the Hummer though.

Tire Sky Vehicle registration plate Vehicle Car

We might have been able to skip this charge entirely, but my son needed some time out of the car, so it worked out okay. 26 minute charge here, ramped from 111kW to 115kW when we unplugged. Delivered 48.56kWh. Enough charge to get us to the next EA station in Valdosta GA. This was another charge that bugged out. We ended up not getting charged at all here. Walked around walmart for about 35 minutes, more than enough to get us to the hotel we were staying at in Lake City that night.

Problem there is I booked the hotel that doesn't have a charger. Didn't feel like trying to negotiate with the front desk people at the other hotel to not tow my truck for stealing their electricity, I decided to go out and get some charge at the nearby FPL fast charger to skip the next morning's charge. Didn't have to do this, but it meant only needing a single charge for our last travel day, so I opted to. After fussing with the charger for 10 minutes in the rain and not being able to get my phone to scan their QR code in their app to start the charge, I gave up and drove the
10 minutes to the nearest EA station. Saw my first Ioniq 5 who got here after I did. I arrived there with 43% charge, stuck around until 81% after 44 minutes and 87kWh delivered, and drove back to the hotel.

Wednesday morning we left with 79% charge. Google maps estimated we could make it to the EA station in Bradenton with only a few percent charge. Decided to try to take the chance, but was going to stop early if it went down too far. This was the first time taking the Hummer to 10% SoC or below. I believe when it estimates you only have 30 miles left, it will display this warning. Second time I saw it was in much colder and snowier weather at 12% SoC.
Cloud Sky Motor vehicle Automotive mirror Automotive exterior


When we got to the EA station at 7%, it was confirmed that two of the four stations were out of order. One of the stations had a car that was at or nearly at a full charge, with no-one around it, and the other one had a line forming for it. Having anticipated this and not wanting to stick around, we took the chance on the drive to the EVGo station that was about 15 miles away. Ended up arriving there at 4% battery. Not having used EVGo in a long time, my phone didn't have my account password saved. Attempted to reset it to be able to log in and the app was all kinds of busted and we couldn't get that to work. Decided trying to use my Amex card but it kept getting declined. Moved off that 350kW station to the other one. The second one wasn't even recognizing my vehicle. Moved to the 50kW station. After I did this, someone in a leaf came up and plugged into the first 350kW station I left. After he was able to get it working, I realized that they didn't have an AMEX logo on the card reader. After trying my Visa it worked and the 50kW station started.

Holy cow are they slow for the Hummer. We went into the store to find something to eat, and the leaf was already gone by the time we got back. Only went from 4% to 9% over the course of about 15-20 minutes. Changed to the 350kW station and immediately was charging up at 274kW instead. By 20% it was up to 289kW, and we went to grab something to eat for real that time. After 23 minutes we had enough charge to get to our final destination.
Watch Communication Device Telephony Gadget Portable communications device

If you're wondering why it slowed down so much, the Hummer will dramatically slow down the rate of charge if the cabin HVAC and battery cooling systems are competing for resources. If you are in a hurry, you can leave the car on but turn the fans all the way to off and it will return to prioritizing the battery. It was in the 80s out here at that point, hadn't seen this behavior previously. I missed the warning in the UI about this occurring but saw it again at a different charge a few days later.

Finally at our destination. We unfortunately didn't have access to a charger here at first, so I decided to run off that evening by myself and take the opportunity to take the tops off. It was awesome, totally met my expectations. I would have liked to just leave the tops off for the rest of our trip, but it didn't end up working out that way even though the weather cooperated.
Sky Plant Vehicle Motor vehicle Cloud


I arrived at this 62.5/125kW chargepoint station with 17% and stayed until 74%. Over 79 minutes, the longest charge session so far for the whole trip, delivered 143.5kWh. Ramped from 105kW to 116kW before starting to taper around 72%(?). Had a chat with someone with an Audi E-tron sportback that wasn't aware GM was even selling the Hummer yet (this was a common theme from anyone who asked me about it).

Lots of little trips over the next week. Had the opportunity to do some overnight L2 charging on the included portable charger. Worked out okay that way. Day before we were going to start the return trip, we went up to the Babcock-Webb wilderness area to try to do some light off-roading. Hard to really know where we were or weren't supposed to drive here. There were some obvious signs in places were they didn't want you to drive, so we didn't go on those roads, but other unsigned roads we did a little bit.
Automotive parking light Cloud Tire Plant Sky

No operation of gasoline motors here!

*Hit the 10 upload limit so I suppose this is a good spot to stop for Part 1.
 

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Great write up! So you mentioned you charged overnight early on at a hotel. I will probably use/look for hotels that have chargers if I take my Hummer on a trip. Are almost all of those L2 chargers? I also tend to stay at Marriott hotels the most when I travel and they usually just have the Tesla chargers, so would I need to invest in one of those TeslaTap adaptors and then I’d be good to go?

last question…I know Tesla is opening up their supercharger network to other brands, are they not available yet or were you just avoiding those chargers? I’m honestly not sure what the latest info was on when those would be available
 

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Great write up! So you mentioned you charged overnight early on at a hotel. I will probably use/look for hotels that have chargers if I take my Hummer on a trip. Are almost all of those L2 chargers? I also tend to stay at Marriott hotels the most when I travel and they usually just have the Tesla chargers, so would I need to invest in one of those TeslaTap adaptors and then I’d be good to go?

last question…I know Tesla is opening up their supercharger network to other brands, are they not available yet or were you just avoiding those chargers? I’m honestly not sure what the latest info was on when those would be available
1. All hotels I’ve ever stayed at have L2 chargers, usually 32 amp at most. Your looking at probably 6-7 mph added in a Hummer. Tesla chargers similar at 40 amps typically but some could be higher at times.

2. Tesla tap has a 60amp version which is the max available. You can’t use that on Tesla superchargers at all. Just slow Tesla L2 chargers. Tesla hasn’t opened up their network in the USA at all yet, but if they do we will need to see if a Tesla to CCS adapter is viable by someone and at what max/compatible. Tesla is rumored to release its CCS to Tesla adapter soon, but that only helps Tesla owners use the CCS networks (which will add even more congestion for us).
 

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Discussion Starter · #6 ·
Great write up! So you mentioned you charged overnight early on at a hotel. I will probably use/look for hotels that have chargers if I take my Hummer on a trip. Are almost all of those L2 chargers? I also tend to stay at Marriott hotels the most when I travel and they usually just have the Tesla chargers, so would I need to invest in one of those TeslaTap adaptors and then I’d be good to go?

last question…I know Tesla is opening up their supercharger network to other brands, are they not available yet or were you just avoiding those chargers? I’m honestly not sure what the latest info was on when those would be available
I've never seen a hotel that has level 3.

I hadn't gotten to it yet, but the one hotel that had 80A Tesla chargers, I wasn't able to charge on them with the teslatap. Teslatap has a number you can call for support, but it was snowing cats and dogs, windy, and cold as hell, so I just opted to use the 32A J1772 the hotel had instead. Most hotels that have charging have had them a while, Tesla originally did 80A, J1772 was most commonly 32A. J1772 cars that take more than 32A are like a "last 4 years" thing still.

Tesla superchargers aren't open to everyone else in the US yet. I half expect Tesla to add CCS cables onto their chargers and switch to it over time instead of requiring adapters.

I'll try to finish up my writeup tonight, but no promises.
 

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I've never seen a hotel that has level 3.

I hadn't gotten to it yet, but the one hotel that had 80A Tesla chargers, I wasn't able to charge on them with the teslatap. Teslatap has a number you can call for support, but it was snowing cats and dogs, windy, and cold as hell, so I just opted to use the 32A J1772 the hotel had instead. Most hotels that have charging have had them a while, Tesla originally did 80A, J1772 was most commonly 32A. J1772 cars that take more than 32A are like a "last 4 years" thing still.

Tesla superchargers aren't open to everyone else in the US yet. I half expect Tesla to add CCS cables onto their chargers and switch to it over time instead of requiring adapters.

I'll try to finish up my writeup tonight, but no promises.
it will be interesting how Tesla implements that, I expect like you say Tesla will add CCS cables, but will Tesla start the chargers with app, or only service vehicles with plug to charge? this remains an open question. Tesla users are not happy about this since CCS equipped vehicles in the USA will outnumber Tesla vehicles soon, and create trouble on their SC network.
 

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Dark-FX: Great post! some things to consider:

Kyle Connor reported on a recent round trip from Ft. Collins, CO to AZ with the Rivian R1T that all the supposedly-500A rated 350 kW-rated EA chargers he used were throttled to 350 amps max. This could explain some of your lower kW-level charge sessions you've had at EA stations, as the Hummer should be able to charge at 400-500 amps through at least about 40-50%., He switched to using EVgo 350's where ever possible, as they delivered at least 450 A to the R1T at low SOC's, right at the R1T's max amp capacity.

Also, apparently you can tap something on the EVgo display and it will break down the charging kW data into charging volts & amps, which is really handy to know for we EV gear-head types:)

I'm still pretty amazed at how effective the Hummer's heat recovery heat pump is at conditioning your cabin in below-freezing temps. 8 kWh in probably 3-4 hours of driving is just a 2 kW heat load draw...way draw than my much-smaller Volt's resistance heater in similar conditions.
 

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Dark-FX: Great post! some things to consider:

Kyle Connor reported on a recent round trip from Ft. Collins, CO to AZ with the Rivian R1T that all the supposedly-500A rated 350 kW-rated EA chargers he used were throttled to 350 amps max. This could explain some of your lower kW-level charge sessions you've had at EA stations, as the Hummer should be able to charge at 400-500 amps through at least about 40-50%., He switched to using EVgo 350's where ever possible, as they delivered at least 450 A to the R1T at low SOC's, right at the R1T's max amp capacity.

Also, apparently you can tap something on the EVgo display and it will break down the charging kW data into charging volts & amps, which is really handy to know for we EV gear-head types:)

I'm still pretty amazed at how effective the Hummer's heat recovery heat pump is at conditioning your cabin in below-freezing temps. 8 kWh in probably 3-4 hours of driving is just a 2 kW heat load draw...way draw than my much-smaller Volt's resistance heater in similar conditions.
Does Hummer have a heat pump?
 

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Discussion Starter · #10 ·
Does Hummer have a heat pump?
Yes. It's a really interesting design. There are two coolant loops that can be mixed together or have heat pumped between them. Uses a lot of excess heat from the drivetrain and power electronics to heat the cabin and battery.

I'm still pretty amazed at how effective the Hummer's heat recovery heat pump is at conditioning your cabin in below-freezing temps. 8 kWh in probably 3-4 hours of driving is just a 2 kW heat load draw...way draw than my much-smaller Volt's resistance heater in similar conditions.
It also got the battery pack to the optimal temperature for fast charging with some of that energy.
 

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Kyle Connor reported on a recent round trip from Ft. Collins, CO to AZ with the Rivian R1T that all the supposedly-500A rated 350 kW-rated EA chargers he used were throttled to 350 amps max.
All those chargers are older ABB units and are NOT rated to 500A, Kyle should take the time to read the charger specifications. ABB 150kw chargers are rated to 350A max, the ABB 350kw chargers are rated to 400A. The Signet units are 500A for either kw output. He needed to go west to Williams Arizona to find those Signet units. Here is the nameplate for an ABB 350kw charger. You need to be at almost 900V to get that power. At 720V nominal the Hummer would be pulling 288kw.

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All those chargers are older ABB units and are NOT rated to 500A, Kyle should take the time to read the charger specifications. ABB 150kw chargers are rated to 350A max, the ABB 350kw chargers are rated to 400A. The Signet units are 500A for either kw output. He needed to go west to Williams Arizona to find those Signet units. Here is the nameplate for an ABB 350kw charger. You need to be at almost 900V to get that power. At 720V nominal the Hummer would be pulling 288kw.

View attachment 2120

Kyle said these were 500 amp-nameplated chargers, not the old ABB's. It appears to be a software-based dial-back. He and Tom Maloughney are very familiar with the older-ABB charger situation and interviewed an EA rep and discussed how EA is working to replace/upgrade those older units a few weeks ago on an IEVs podcast. Kyle contacted EA about the recent situation with the newer units and EA was cagey about explaining it. So for the near future, if he wants to do a 0-100% fast charge speed test on a vehicle that requires more than 350 A, he's driving it down to Denver, which has the nearest EVgo 500 A-rated Signet 350 kW charge station. Here's a link to his R1T charging video

Out of Spec R1T 0-100% fast-charging test video
 

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@ Dark: I was looking at a probable charging curve for the Hummer based on your reports and probable internal pack heat generation. Looks like at about 300 kW, you could be generating about 22 kW of heat in the pack. The pack thermal mass is like a concrete slab and can absorb a lot of that, but you'd need at least 10 kW of cooling from the TMS to knock down the heat flux some and keep the cells from rising over 45 deg. C before the BMS starts backing off the charge speed at the higher SOC. That's probably about all the AC compressor can make, so sending 5 kW to cool that cabin (and with the massive glass-panel roof, even at 80's F air temperature a sunny day could create that cabin cooling load.).

I don't know if you watched the History channel documentary, but there's a very brief moment where they're assembling the alpha prototype and you can see the front glycol cooling radiator - or maybe the AC condenser. Hard to tell which. Pretty darn big for an EV
 

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Kyle said these were 500 amp-nameplated chargers, not the old ABB's. It appears to be a software-based dial-back. He and Tom Maloughney are very familiar with the older-ABB charger situation and interviewed an EA rep and discussed how EA is working to replace/upgrade those older units a few weeks ago on an IEVs podcast. Kyle contacted EA about the recent situation with the newer units and EA was cagey about explaining it. So for the near future, if he wants to do a 0-100% fast charge speed test on a vehicle that requires more than 350 A, he's driving it down to Denver, which has the nearest EVgo 500 A-rated Signet 350 kW charge station. Here's a link to his R1T charging video

Out of Spec R1T 0-100% fast-charging test video
He went up I-17 and east across I-40, those are all the old ABB ones. Go look at the photos on Plugshare. Currently there are 4 sites in Arizona that have the Signet 350kw chargers:
  • Williams
  • Kingman
  • Quartzsite
  • Showlow
Phoenix has some local sites with Signet, but those are all 150kw chargers. The route from Phoenix to Denver was one of the early completion routes for EA and at the time they were all ABB chargers. I have charged at several Signet chargers, they all go beyond 400A for my Mach E.

Edit: I checked on Plugshare, every EA site on I-40 and up I-25 are all ABB, you can easily tell the difference, ABB has plugs on the front of the units, Signet has plugs on each side of the units.
 

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Discussion Starter · #17 ·
Dark-Fx, what does your son think of the Hummer EV overall and how it compares to your previous family vehicle?
He seemed to enjoy it but probably had enough of being inside it after that trip. It's a little hard to get him into the car seat with how high up the seats are from the ground, but we have one of those seats that rotates, so that helps a lot. Rear facing seats take up a surprising amount of the space that should be available for the driver, but at 5'10" it was just fine for our trip.

Obviously the amount of storage space available, with the frunk and bed, is significantly more than that of the Polestar. We brought way more stuff than we needed to because we could. Not sure when our next vacation is, but we are likely going to take the Rivian.

The day after I got my Rivian- it, the Hummer, and the Polestar 2 were sitting in the driveway. I asked him which car he wanted to take and he pointed to the polestar. Of course that could be because I said "car" and the other ones are "trucks". If not that, then if I had to guess it's just because the polestar has the best ride of the three, OPD is the smoothest and easiest to use at low speeds.
 

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Discussion Starter · #18 ·
@ Dark: I was looking at a probable charging curve for the Hummer based on your reports and probable internal pack heat generation. Looks like at about 300 kW, you could be generating about 22 kW of heat in the pack. The pack thermal mass is like a concrete slab and can absorb a lot of that, but you'd need at least 10 kW of cooling from the TMS to knock down the heat flux some and keep the cells from rising over 45 deg. C before the BMS starts backing off the charge speed at the higher SOC. That's probably about all the AC compressor can make, so sending 5 kW to cool that cabin (and with the massive glass-panel roof, even at 80's F air temperature a sunny day could create that cabin cooling load.).

I don't know if you watched the History channel documentary, but there's a very brief moment where they're assembling the alpha prototype and you can see the front glycol cooling radiator - or maybe the AC condenser. Hard to tell which. Pretty darn big for an EV
Apparently I did actually take a picture of the message.
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That is typical on most EV, it cannot cool the cabin and battery at the same time, I wonder how this will work in AZ summers?
One possible solution would be if the driver acts proactively and "pre-conditions" the cabin for a short AC shutdown prior to starting the session. Turn the temp setting way down when getting near the charger and pre-cool the cabin, then shut it off just before starting the charge session. The pack will probably be OK with this protocol, as it wants to be "warm" (most OEM's target about 30 deg. C) to start fast-charging at optimal speeds.
 
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