Larger batteries require larger EV chargers

The GMC Hummer EV can be seen as the current zenith of EV technology, as its massive 200 kilowatt-hour battery pack provides an EPA-estimated driving range of 350 miles. This made the monster truck the perfect candidate for an EV road trip to investigate the practicalities of driving normal combustion car trips in an EV.

Along the way, we learned that even with a huge battery, there’s still accommodation to be had. Because of the huge battery, there is actually still accommodation to be had. That’s because we discovered that while a large battery provides good range, it also takes a long time to recharge.

When we took the $108,000 GMC Hummer EV on a road trip, we started with a 75 percent state of charge and an estimated driving range of 250 miles. After 234 miles of 60 mph travel on mostly two-lane highways in mild mid-50s temperatures, we reached an EVgo 50 kW DC charger showing 30 miles of remaining range with the truck averaging a paltry 1.6 miles per kWh. Still, by avoiding the higher speeds of Interstate driving, we had exceeded the expected driving range.

Image courtesy of Dan CarneyIMG_2270.JPG

It wasn’t quite off-roading, but our Hummer EV got a little dirty and delivered us to the trailhead.

But this is where we discovered the pitfall of the large battery. A 50 kW DC charger is ostensibly a “fast” charger, but it added juice to the huge package at an endless rate. In 26 minutes, it increased the driving range by just 47 miles with an additional 17.2 kWh!

From there we went to our hotel which had a Tesla Level 2 AC charger. Charging it overnight, we found the Hummer in the morning showing 216 miles of range. To use the hotel’s only charger (which will surely be a problem in the future) they required us to use $20 valet parking. But self parking there was $15, so the fee was $5 net.

By the time we left the hotel, 81 miles of Interstate driving took 118 miles out of the Hummer’s projected remaining range, leading to a top-up of a 350 kW Electrify America charger. When the truck was plugged in, the charging station first said “the vehicle timed out.” Disconnected and reconnected, the charging station then declined the credit card. Unplugged again and it again said vehicle timed out. Fourth time through this and after more than five minutes wasted it started charging.

It seemed to try to make up for lost time, adding 73.5kWh in 17 minutes and returning the predicted driving range to almost exactly the same distance we had started back at the hotel. Another 132 miles on the road but with only 110 miles of driving range on rural highways we reached the next hotel. This hotel also had a Tesla Level 2 charger, but no adapter for use with the Hummer’s SAE charging connector, so we took it to a nearby commercial 6.4kW Level 2 charger. This one needed 24 hours to fully charge the Hummer, which cost $50.

Another day of driving and staying overnight in a hotel with no charging facilities led to us stopping for lunch the next day and trying to boost the battery on a Blink Level 2 charging station while eating and sight-seeing. This charger was slow, but it seemed like we’d be there long enough for it to make a meaningful difference. It didn’t because the charging station crashed and stopped working after adding 12 miles of driving range.

The Lobster’s huge battery meant we could still drive to dinner, but there wasn’t enough juice to get home. The Hummer’s navigation system didn’t see any 350kW fast chargers along our route but Electrify America’s app said there were some at a Walmart, so we stopped there just before dinner.

This charger added 105kWh in 24 minutes, giving us plenty of energy for the rest of the trip home. Although this charging station, which was an ItalDesign charger, charged the truck flawlessly, its display was unable to show the Hummer’s charging progress during charging. An adjacent charging station had the same problem with the Mini EV it was charging. Software problems seem inevitable at this point.

Image courtesy of Dan CarneyIMG_2337.JPG

During our 900 miles of electrified driving, the Hummer EV averaged 1.6 miles per kWh. So while we appreciated the large battery pack and the long driving range it enables, the Hummer is handicapped by the long charging times of its battery capacity and energy requirements.

All vehicles will benefit from a charging network that is not only larger, but also more reliable, with fewer problems connecting and less likely to end the charging session prematurely, both of which were issues we encountered.

But above all, the charging network needs to be faster, with 350kW chargers as standard, so drivers can be sure they can quickly add the power they need and that if someone else uses the available charger they’ll be ready quickly. A large battery only provides a large need for electricity that most of today’s charging stations cannot quickly satisfy.

More efficient EVs with large enough batteries and an improved charging network that is faster and more reliable will be needed to make EV road tripping hassle-free enough for most drivers to consider going electric for visits home on Thanksgiving.

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