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Discussion Starter · #1 ·
https://insideevs.com/gm-researcher...energy-density-fast-charging/#comment-1454786

Hypothetically, let's say you had the choice to do one of 2 things: 1) keep your Bolt as is (238 miles, 50 kW fast charging), or 2) change to a higher capacity pack that offered 400 miles of range but ONLY L2/7.2 kW charging (no fast charging).

Would you rather have your Bolt as it is currently speced, or would you switch to the longer range/no fast charging battery? Let's say price stayed the same.

From my experiences with my Bolt, I've found that destination charging can be just as important as fast charging on long (exceeding the Bolt's 238 mile range) road trips.

In a perfect world, I'd like both the range AND fast charging, but if I had to choose just 1....I'm not sure to be honest.
 

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Dang. I thought you were going to give us the choice between two hypotheticals. EG: fast charging (150+kW), or long range (400 miles). Considering fast charging is offered from teh factory for $750, it doesn't really seem like much of an impediment. However, a 400 mile range would probably mean a 100 kWh battery which would be in another price point.

As stated, I'd still prefer the fast charging. I recently drove over 900 miles in the ICE in 15 hours, and that would be impossible in a BEV with L2 only - even if doubling the time frame. A reasonable minimum of say 125 kWh would add 18+ hours to the trip. However, 175 kWh with a fast charger would add maybe 5+ hours to the trip.

Now, what about if you had the option between 150+kW charging with 240 mile range, or 50kW and 400 mile range?
 

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I have just written somewhere else on this forum that it would be unreasonable to deprive your Bolt of the fast DC charger option, but if we were indeed talking 400 mi on one charge, I would be inclined to contradict my earlier statement.

The hypothetical 400 mi range would give me 200-240 winter miles, which translates into 100 or better miles of spare range, which all but precludes the need for DCFC.
 

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Great question.

I'd go for currently spec'd, though my true preference would be current range with actually fast/faster charging. Bolt charging realistically tops out at 25kW in cold weather (personal experience and references below; warm weather TBD).

When I road trip, I can easily go beyond 400mi in a day. Low temps also seriously ding range, so 400mi would turn into more like 250mi in the winter.

When I road trip, I also can't be guaranteed to be near a charger for long periods of time. I frequently travel to see friends in a town about 100mi away. We often go hiking or drive to something while I'm there, and the trip usually entails a top up. I'm not usually in one place with an L2 for long enough to make any appreciable gains, while taking a 1-2hr lunch somewhere with an L3 blends seamlessly into the day.

A good road trip metric for BEVs would probably be something like hrs/100mi, which would be 100mi/speed + time to charge energy depleted at that speed. Whatever range you have at the outset would essentially be a head start.

That's my take.

Reference:
- https://elbil.no/the-biggest-electric-car-test-in-winter-wonderland-ever/
- https://bro05.blogspot.ca/2017/12/this-is-not-going-to-go-way-you-think.html
 

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That's an easy one: true fast charging all the way. By true fast charging I mean without the artificial percipitous taper and current limitations that current Bolts carry. The Spark EVs charge profile is just about perfect.

The reason for fast charge is that it decouples the dwell time from charging. L2 is designed for overnight charging. So even though a 400 mile range battery clocking in at 96-100 kWh clearly has the range, the L2 charger for it will likely top out at 15.4kW ([email protected]) of power in order to completely recharge overnight. That covers a bit more than 60 miles of recharge power per hour presuming an average of 4 miles/kWh.

That 60 miles/hour recharge is the limitation. While it's fine the 95% of the time of normal usage, that last 5% will be painful. 3 hours recharge to get 180 miles on a road trip is going to hurt. And that of course presumes you can find an L2 that'll deliver the full 15.4 kW of power necessary to recharge at that rate.

OTOH a true DC fast charge that can deliver 150 kW up to an 80% first taper would be money. A Bolt in that configuration could recharge 192 miles in 30 minutes. So either road tripping, or just an opportunity top off, 15-30 minutes can deliver a boatload of energy to the point that the "limited" range really doesn't matter.

I decided to defer on the Bolt, getting a Fiat 500e used instead. So I have the limitation of both low range (80 miles) and slow charging (6.6 kW max). Trust me, I'd keep the 80 mile range if I could recharge in 15 minutes. It's a no brainer.

ga2500ev
 

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I'm happy with the range the bolt has, I think in the not so distant future that you will be able to charge in less than 10 minutes at most charging stations.

As battery weight and size comes down the cars will be able to go further just because the weight has been eliminated.

Porsche is going to make an EV, from what I heard they will have a 800 amp fast charge with a 600 mile range that will charge in 15 min or less.
 

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Discussion Starter · #8 ·
After thinking about it, I think I would still need some kind of fast (50 kW+) charging in any long range BEV, Bolt or otherwise, unless I could be guaranteed destination charging was available. Well, unless the other option was a pack good for 1,000 miles. But that is fantasy at the moment.

Even a 400 mile pack with no fast charging would be a problem for some of my road trips, such as my MD-CT one I take once or twice a year. There is no convenient destination charging at the place I usually stay at in CT, and I'd have to go out of my way to find a station to park my Bolt at for the night.

I think GM picked a nice medium with the current Bolt's specs. Hopefully increased fast charging ability (while not sacrificing range) is something GM is working on for future models.
 

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I've owned a bolt since the end of November, 2017, and I've yet to
  • Drive more than 150 miles in a day
  • Discharge the battery lower than 40%
  • Actually use a DC fast charger

My average charge adds less than 7 kW to the battery, and I'm pretty much always using Hilltop Reserve.

For most days, arguably a 60 kW battery is an indulgence for me. It just provides reassurance that I'll be ready for the unexpected.

For serious road trips, I might go 150 miles, I might go 250, or I might drive 450 miles. It's not unreasonable for someone to want to drive from Albany, NY to Toronto, ON. There is a toll route that is only 384 miles (other routes top out at more than 400 miles), but do you want to drive 384 miles on the freeway in a car whose EPA range tops out at 400 miles? You're probably not going to make it in summer unless you drive slow and you certainly won't make it in winter.

For most EV drivers, long road trips will always be the outlier, and as such DC fast charging is more sensible than giving every car a huge battery they mostly never need and might still not be enough.

And for 400 mile trips in a Bolt, DC fast charging is no real hassle. Set out, drive for about 3 hours, stop for lunch and a break, fast charge for 45 minutes while you eat, get on the road again feeling refreshed and finish your trip.
 

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https://insideevs.com/gm-researcher...energy-density-fast-charging/#comment-1454786

Hypothetically, let's say you had the choice to do one of 2 things: 1) keep your Bolt as is (238 miles, 50 kW fast charging), or 2) change to a higher capacity pack that offered 400 miles of range but ONLY L2/7.2 kW charging (no fast charging).

Would you rather have your Bolt as it is currently speced, or would you switch to the longer range/no fast charging battery? Let's say price stayed the same.

From my experiences with my Bolt, I've found that destination charging can be just as important as fast charging on long (exceeding the Bolt's 238 mile range) road trips.

In a perfect world, I'd like both the range AND fast charging, but if I had to choose just 1....I'm not sure to be honest.
For me, 400 miles of range puts me at 6 to 7 hours of driving, when I am on a road trip I drive around 10 hours a day, 600 to 700 miles... having 400 miles of range and no DCFC would mean never taking the Bolt on a road trip.

Also, for anyone who takes road trips that only drives 400 miles in a day, 400 miles of range and presuming the same efficiency implies a 120 kWh battery pack, at 7.2 kW charging it would take 16 hours of charging. If you start your drive at 6:00 AM and drive for 7 hours and stop at a hotel with a 7.2 capable L2 (more likely 6.2) , you would pretty much have to pay for two nights stay to get back up to a full charge, or sit out in the parking lot from check out time until you reached full charge before continuing your journey.

For me, 3 to 3 and a half hours of driving (200ish miles) is about my wife's maximum bladder capacity, so if we ever get a CCS charging network, driving for 200 miles and a stop to eat, rest, bathroom break etc for an hour while the car re-charges would only increase my day of driving on a 600 mile a day schedule from two 15 min stops for gas and a gas fill up at a gas station before checking into the hotel and 9 hours of driving (9.45 hours total) to two one hour brakes with 9 hours of driving (11 hours total) with L2 charging at the hotel to fill up over night. I can take an extra hour and 15 min on my trip a lot better than the 400 mile but only L2 charging option. I would actually focus more on faster DC charging rather than larger battery pack since the wife's bladder capacity determines my stop interval in anything ICE or EV with more than 200 miles of range :)

Keith
 

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I don't have a Bolt, but I'd go for one with less range and a lower price. Given your question, I'd take DCFC over higher capacity, all else being equal (price, performance, etc). I have no intention of driving long distances, but if I did, I'd rather charge quickly rather than slowly and infrequently.
 

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Actually, I want a third choice ... 160-200 miles of range, no DCFC ... and $10K less expensive.

I want a BEV that can easily do 130-150 miles in "cold" (40 degree) weather, combined with my 30-mile-electric range PHEV. PHEV for around town (10-20 miles most days), BEV for almost everything else, and PHEV for the road trips so I can add 10 gallons in 4 minutes and drive another 400 miles. But then I have 2 drivers and two cars. Still... that's what I want.
 
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To be a really effective road trip car, I would want an EV to be able to run at 70 MPH for about 4 hours, and then be able to charge quickly enough so that after a 1-1.5 hour charge, it would be ready to do another 4 hours at 70 MPH. That would allow for a 500 mile day with just one relatively long stop for a meal/charge. Or an even a 700 mile day if you put in another stint after dinner.

Unfortunately, we're still a long way from achieving that target. If one is optimistic, and assumes a Bolt will get 3.0 miles per KWH when doing 70 on the freeway, you get a realistic range of about 150-160 miles between recharge stops, (60 KWh * 3 m/kwh = 180 miles, less a 20-30 mile safety margin). Which at 70 MPH means stopping every two hours or so, for a DCFC that at best would need to be at least 75 minutes long to enable another 2 hours of running at 70 MPH. Doubling the battery size AND upping the DCFC charge rate to 100+ KW would pretty much do the trick, although as Fivedoor pointed out, with a 120 KWh battery, you'd really need access to a DCFC rather than a level 2 charger when stopping for the night in the middle of your trip, as the 18 hour L2 recharge time would simply not cut it.
 

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To be a really effective road trip car, I would want an EV to be able to run at 70 MPH for about 4 hours, and then be able to charge quickly enough so that after a 1-1.5 hour charge, it would be ready to do another 4 hours at 70 MPH. That would allow for a 500 mile day with just one relatively long stop for a meal/charge. Or an even a 700 mile day if you put in another stint after dinner.

Unfortunately, we're still a long way from achieving that target. If one is optimistic, and assumes a Bolt will get 3.0 miles per KWH when doing 70 on the freeway, you get a realistic range of about 150-160 miles between recharge stops, (60 KWh * 3 m/kwh = 180 miles, less a 20-30 mile safety margin). Which at 70 MPH means stopping every two hours or so, for a DCFC that at best would need to be at least 75 minutes long to enable another 2 hours of running at 70 MPH. Doubling the battery size AND upping the DCFC charge rate to 100+ KW would pretty much do the trick, although as Fivedoor pointed out, with a 120 KWh battery, you'd really need access to a DCFC rather than a level 2 charger when stopping for the night in the middle of your trip, as the 18 hour L2 recharge time would simply not cut it.
This post defines the challenge of EV adoption. In theory, the above list are not unreasonable expectations which are easily achievable with virtually every ICE vehicle. Unfortunately the battery pack for this will easily double or even triple the price of the BEV. Very few will spend $100K+ to get a vehicle that in ICE would cost $17K. So it's simply an untenable proposition for a mainstream vehicle. The worst part about it is that for almost everyone who purchased such a vehicle, those capabilities would only be in use well less than 5% of the miles that vehicle would ever be driven. Which means that virtually the entire life of the vehicle would be spent hauling around extra unused capacity. Honestly, it's the same situation with folks who own large SUVs but do the dialy commute by themselves. I know, I've been one of them in the past.

As for the L2 recharge, the situation really isn't that dire. Almost to a vehicle, the internal charger is sized to fully recharge the battery in 8-9 hours. For a 120 kWh pack, the internal charger would need to be 15.4 kW which is [email protected] There are L2 chargers with that capacity, including JuiceBox 75A chargers, Tesla HPWC, and Clipper Creek. Plus the fact that of course DCFC would be a must, as I said the situation isn't as dire as it would seem.

ga2500ev
 

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Discussion Starter · #17 ·
I completed some GM owners survey a while back. I don't remember all the details, but it presented me various configurations of fictional BEVs with varying range/degradation/fast charging/acceleration/price specs. Some had great range and fast charging, but poor battery life. Others had shorter range/slower fast charging/better battery life, but worse acceleration. I think some had "fast" charging ability almost as slow as the Bolt's 7.2 kW rate.

I'm hoping GM's next generation of BEVs (whatever follows the Bolt) have above average range, 100+ kW fast charging, AND spirited performance at a reasonable price. GM favored range over fast charging with the Bolt, and I think I'm actually fine with that approach.
 

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Actually, I want a third choice ... 160-200 miles of range, no DCFC ... and $10K less expensive.

I want a BEV that can easily do 130-150 miles in "cold" (40 degree) weather, combined with my 30-mile-electric range PHEV. PHEV for around town (10-20 miles most days), BEV for almost everything else, and PHEV for the road trips so I can add 10 gallons in 4 minutes and drive another 400 miles. But then I have 2 drivers and two cars. Still... that's what I want.

I like your choice and I prefer to pay less than buy more range than what I need. Where I live, any point is less than fifty miles away in the same direction, and I never drive faster than 60 MPH, so a 100-mile range is more than enough. And I do own a Level 2 EVSE that was assembled and set in 2014 at 7.2 kW before GM announced the Bolt EV. I can recharge nightly while I sleep.:)
 

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As for the L2 recharge, the situation really isn't that dire. Almost to a vehicle, the internal charger is sized to fully recharge the battery in 8-9 hours. For a 120 kWh pack, the internal charger would need to be 15.4 kW which is [email protected] There are L2 chargers with that capacity, including JuiceBox 75A chargers, Tesla HPWC, and Clipper Creek. Plus the fact that of course DCFC would be a must, as I said the situation isn't as dire as it would seem.
Fair enough, but that's really only valid for home charging. If you're going somewhere then you're stuck with what you find. For example, there are plenty of L2 chargers (destination chargers?) near me that only provide 6kW ([email protected]). And quite a few places I've looked at going to are in that ballpark - Hershey Park for example. It's rare near me to see an L2 charger offering more than 32A. A vehicle's ability to take 15kW wouldn't help. As DCFC availability increases, then the point will become moot - assuming you have, in the case of the Bolt, popped for the $750 option.
 
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