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 Post subject: DC fast charging the 2017 e-Golf twice, back to back
PostPosted: Sun Apr 29, 2018 8:40 pm 
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Hi everyone,

I've read in a couple places on this forum that, at least in the 2015 models, DC fast charging the e-Golf more than once, back to back, is bad for the battery, and potentially voids the battery warranty. Is this still true for the 2017 model?

The reason I'm asking: I'm thinking about buying a 2017 e-Golf, but to make this purchase worth it, I would need to use the e-Golf to make 3-4 trips a year from New York City to Massachusetts and back again. This trip is roughly 250 miles each way, so to do the trip, I would need to DC fast charge twice, back to back. Then on the return 250 mile trip, 2-3 days later, I would again need to fast charge twice, back to back. So how bad would it be to DC fast charge the e-Golf twice, back to back, during these 3-4 annual trips (6-8 times total)? Would this really void the battery warranty? And would this significantly affect the battery's long term capacity, or does back to back fast charging only really degrade the battery if you do it constantly?


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 Post subject: Re: DC fast charging the 2017 e-Golf twice, back to back
PostPosted: Sun Apr 29, 2018 9:54 pm 
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Kieran973 wrote:
Hi everyone,

I've read in a couple places on this forum that, at least in the 2015 models, DC fast charging the e-Golf more than once, back to back, is bad for the battery, and potentially voids the battery warranty. Is this still true for the 2017 model?

The reason I'm asking: I'm thinking about buying a 2017 e-Golf, but to make this purchase worth it, I would need to use the e-Golf to make 3-4 trips a year from New York City to Massachusetts and back again. This trip is roughly 250 miles each way, so to do the trip, I would need to DC fast charge twice, back to back. Then on the return 250 mile trip, 2-3 days later, I would again need to fast charge twice, back to back. So how bad would it be to DC fast charge the e-Golf twice, back to back, during these 3-4 annual trips (6-8 times total)? Would this really void the battery warranty? And would this significantly affect the battery's long term capacity, or does back to back fast charging only really degrade the battery if you do it constantly?


Rent a car for those trips. Problem solved.

DC Fast charging does not balance charge the battery pack, which is why they want you to recharge at a Level 1 or Level 2 AC charging EVSE, every other fast charge, so that the battery pack can be equalize charged, all the cells. Important for longevity of the battery cells. And for not voiding your charging warranty. BTW, VW logs every recharge you do, voltage, amps, time, all that stuff. Memory is cheap. Plus how do you think they can let you see all of that info on your smart phone, or push text when your car is completely recharged?

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 Post subject: Re: DC fast charging the 2017 e-Golf twice, back to back
PostPosted: Sun Apr 29, 2018 10:38 pm 
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Joined: Wed Apr 18, 2018 8:44 pm
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"Rent a car for those trips. Problem solved."

What I would actually do is just buy a different car. If you really can't take the e-Golf on one medium distance road trip (250 miles) without not only voiding the battery warranty, but damaging your battery permanently, then that completely defeats the purpose (for me anyway) of even buying a 125 mile EV with fast charging. Why not just stick with a used 80ish mile EV in that case? My work commute is only 22 miles round trip. On the weekends the farthest I usually travel in one day is 40 miles round trip. The only reason for me to buy a greater than 100 mile EV would be to use it for out of town trips some of the time. But if VW, because of poor battery thermal management, offers a DC fast charging option that you can't really use, then their 125 mile e-Golf isn't much different from their 83 mile e-Golf. What they're essentially saying is: this is still just purely a city car. And if that's the case, then buying a used 80 mile EV for 7-12K, or a new Chevy Bolt or Honda Clarity for 23-27K, both seem like much better value propositions than buying a new 2017 e-Golf....


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 Post subject: Re: DC fast charging the 2017 e-Golf twice, back to back
PostPosted: Mon Apr 30, 2018 12:12 am 
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Joined: Wed Apr 04, 2018 12:12 am
Posts: 44
Location: Sunnyvale, CA (NoCa)
Kieran973 wrote:
"Rent a car for those trips. Problem solved."

What I would actually do is just buy a different car. If you really can't take the e-Golf on one medium distance road trip (250 miles) without not only voiding the battery warranty, but damaging your battery permanently, then that completely defeats the purpose (for me anyway) of even buying a 125 mile EV with fast charging. Why not just stick with a used 80ish mile EV in that case? My work commute is only 22 miles round trip. On the weekends the farthest I usually travel in one day is 40 miles round trip. The only reason for me to buy a greater than 100 mile EV would be to use it for out of town trips some of the time. But if VW, because of poor battery thermal management, offers a DC fast charging option that you can't really use, then their 125 mile e-Golf isn't much different from their 83 mile e-Golf. What they're essentially saying is: this is still just purely a city car. And if that's the case, then buying a used 80 mile EV for 7-12K, or a new Chevy Bolt or Honda Clarity for 23-27K, both seem like much better value propositions than buying a new 2017 e-Golf....


You can fully charge at the beginning with AC and drive slowly (150 miles is doable I guess) than charge with DC and again AC in the end. Also you can stop for 1-2 hour brake and charge on AC somewhere in the middle. It's not most convenient way but as you said its only 3-4 times per year.

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VW Caddy 2006
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 Post subject: Re: DC fast charging the 2017 e-Golf twice, back to back
PostPosted: Mon Apr 30, 2018 8:59 am 
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Only VW knows what back to back DCFC sessions will do to your battery. I think the warranty issue is a bit murky - you could try asking someone at VW. I believe the main issue is high battery temperatures as both high speed driving and high speed charging generate heat within the pack which, because the pack is passively cooled, lead to high temperatures. I think driving this trip in the winter would be less of an issue than driving it in the summer due to the ambient temperatures. If you can drive 55 to 60 mph, you may be able to limit the heating due to usage, and might be able to squeak out 110 to 120 miles before recharging. If you charge to 90%, you'll probably be able to get another 90 miles, so then you could stop again for a 3 hours AC charge to pick up enough energy to make it to your destination. You could also perform a second DCFC session but not fully charge the battery, to limit temperature increases.

I am planning this sort of trip only once a year and plan to follow the first DCFC session with AC charging, as I have no choice, given where I plan to drive has very sparse EV infrastructure.

You'll need to decide about cost, convenience, longevity, etc. to figure out which car meets your needs.

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 Post subject: Re: DC fast charging the 2017 e-Golf twice, back to back
PostPosted: Mon Apr 30, 2018 9:16 am 
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Joined: Mon Oct 05, 2015 2:01 pm
Posts: 2105
Kieran973 wrote:
"Rent a car for those trips. Problem solved."

What I would actually do is just buy a different car. If you really can't take the e-Golf on one medium distance road trip (250 miles) without not only voiding the battery warranty, but damaging your battery permanently, then that completely defeats the purpose (for me anyway) of even buying a 125 mile EV with fast charging. Why not just stick with a used 80ish mile EV in that case? My work commute is only 22 miles round trip. On the weekends the farthest I usually travel in one day is 40 miles round trip. The only reason for me to buy a greater than 100 mile EV would be to use it for out of town trips some of the time. But if VW, because of poor battery thermal management, offers a DC fast charging option that you can't really use, then their 125 mile e-Golf isn't much different from their 83 mile e-Golf. What they're essentially saying is: this is still just purely a city car. And if that's the case, then buying a used 80 mile EV for 7-12K, or a new Chevy Bolt or Honda Clarity for 23-27K, both seem like much better value propositions than buying a new 2017 e-Golf....


VW builds cars that are mass production. They build cars that primarily cater to the needs of European drivers. American drivers are an afterthought, as far as VW is concerned with meeting American's transportation needs.

For people that used to drive 15 to 20k miles a year, VW made the TDI models in diesel. For those that drive 8 to 14.9k miles a year, they make a gasoline model. For those that drive less than 8k miles a year and why VW offers so many 7.5k miles a year leases on e-Golfs, they offer their inner city model e-Golf electric car, with less range between refilling the battery.

Americans tend to buy too much car, something that will fulfill 100% of their needs less than 1% of the time, and that is overkill and too much vehicle for the other 99% of their driving, when they should buy something that will meet 99% of their needs, and rent the proper tool for the other 1% of their transportation needs.

Figure out what best suits you. You can quick charge once, or drive a little slower, say 55 MPH to get to your 250 mile destination and then do a full Level 2 240V recharge once you get to your destination, and that would fulfill the battery requirements for recharging. The other option is to do a DCFC midway during your trip, and then once the DCFC is finished, immediately go use a Level 2 EVSE right after the DCFC is complete for another 30 minutes until your battery is now fully recharged. That way, you get the equalize recharging done on the battery, and you save recharging time over a straight 4 to 5 hour level 2 recharge.

You have to understand the what's and why's of LiPo battery chemistry, and it's limitations, before buying an all electric car. The e-Golf is best suited as an inner city crawler, not an interstate road burner that you can just pile on the miles on pushing air out of the way and wasting energy driving at top speed. That's not it's niche or forte.

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 Post subject: Re: DC fast charging the 2017 e-Golf twice, back to back
PostPosted: Mon Apr 30, 2018 9:32 am 
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I thought about following the DCFC with an AC charge, but my wife is about to have a baby, so I'm not sure that making the family wait around for 1-3 hours for the Level 2 charge to complete is the best idea (even though, if I were alone, I wouldn't mind doing this).

As for using the e-Golf for the winter trips rather than the summer trips, I thought about that too, but I figured I just wouldn't have the range to complete this trip in the winter. Maybe I'm wrong.

The way I imagine this trip working in the summer is: charge to 100% right before leaving (range at 125 EPA), drive 100 miles (range at 25 EPA), DC charge up to 80% in 25 minutes (range at 100 EPA), drive 80 miles (range at 20 EPA), DC charge a second time up to 64% in like 20 minutes (range at 80 miles EPA), drive 60 miles (range at 20 miles EPA) and arrive at destination.

Obviously, with more careful driving, real-world range can be higher than EPA estimates. In my non-hybrid Honda Civic right now, I'm averaging about 25% better than EPA (45 real-world MPG vs. 36 MPG EPA), so at that rate, in the e-Golf I'd have more like a 156 mile range at 100%, etc. Assuming I could rely on this 25% efficiency gain during all road trips (I drive slow on the interstate, in the right lane), then I could maybe pull off a trip from NYC to Mass with only one DCFC. But this is still only an if, and traffic, rainstorms, etc. could be the difference between making it with one DCFC stop vs. not making it, and having to do a Level 2 charge, or even worse, tow the car....

Though I am encouraged by Joules Thief's reported 6+ miles/kWh averages (albeit mostly in city driving). If I could even pull off 5 miles/kWh on a road trip, by driving 62 mph in the right lane in 65 mph zones and driving 50 mph in 55 mph zones, then I think I could make it in one stop....


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 Post subject: Re: DC fast charging the 2017 e-Golf twice, back to back
PostPosted: Mon Apr 30, 2018 9:58 am 
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"Americans tend to buy too much car, something that will fulfill 100% of their needs less than 1% of the time, and that is overkill and too much vehicle for the other 99% of their driving, when they should buy something that will meet 99% of their needs, and rent the proper tool for the other 1% of their transportation needs."

Very true. I think you can save a lot of money by realizing that not every car has to do all things, and making sure you're not paying for more capacity than you really need. The issue with me, though, is that our second car, my wife's car, is a Honda CRV, and I'm trying to limit the use of that vehicle on road trips - both for financial reasons, but also because of climate change/lowering our own carbon footprint. I realize that whether we put 5,000 miles a year or 15,000 miles a year on our CRV, this will not be the determining factor in whether the gulf stream collapses, the polar ice caps melt, etc. - but seeing as there's no real plan for dealing with climate change (most countries aren't going to meet the Paris limits), this just helps me stay a little more sane in my day to day. So, what I'd really be looking for in either an EV or PHEV is a car that can do at least some of our out-of-town road trips, that way we can limit the CRV's use as much as possible. I'm also considering the Honda Clarity PHEV and the Chevy Bolt. Though what I like about the e-Golf is:

1.) after EV tax incentives and dealer discounts, it can supposedly be purchased for less than $20K.

2.) it has a better looking exterior, a more comfortable and higher quality interior, more cargo space, and better ride and handling than the Chevy Bolt.

3.) it's a full EV, with way less parts than a PHEV, so in theory, it should have less long-term maintenance issues and costs than a PHEV (though I'm not sure if this is actually even true). Ideally, even after the battery degrades to a 90 mile range at the 8 year mark, you could get another 5 or so years out of it as commuting/grocery-store car (though this is why I was asking about the long-term dependability of this vehicle).

4.) its EPA ratings seem to be conservative - its real-world range seems to be more like 150 miles, and 4-5 miles/kWH as an all-weather average seems doable.

In my mind, the only advantage that the Chevy Bolt has on the e-Golf then is that the occasional 250 mile trip can be done in 0-1 DC fast charging stops, whereas the e-Golf would require 1-2 stops. But if I realistically couldn't take the e-Golf out of town at all, then this would force me to have to re-evaluate...

JoulesThief, that's an interesting idea you propose - doing a Level 2 charge immediately after the DC fast charge. Do you mean, though, that I would DC fast charge to 80%, then switch to Level 2 charging for the last 80-100%? Or do you mean fast charge to 80%, drive around for a a few miles, and then do a Level 2 charge? Thanks.


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 Post subject: Re: DC fast charging the 2017 e-Golf twice, back to back
PostPosted: Mon Apr 30, 2018 10:14 am 
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Joined: Mon Oct 05, 2015 2:01 pm
Posts: 2105
Kieran973 wrote:
"Americans tend to buy too much car, something that will fulfill 100% of their needs less than 1% of the time, and that is overkill and too much vehicle for the other 99% of their driving, when they should buy something that will meet 99% of their needs, and rent the proper tool for the other 1% of their transportation needs."

Very true. I think you can save a lot of money by realizing that not every car has to do all things, and making sure you're not paying for more capacity than you really need. The issue with me, though, is that our second car, my wife's car, is a Honda CRV, and I'm trying to limit the use of that vehicle on road trips - both for financial reasons, but also because of climate change/lowering our own carbon footprint. I realize that whether we put 5,000 miles a year or 15,000 miles a year on our CRV, this will not be the determining factor in whether the gulf stream collapses, the polar ice caps melt, etc. - but seeing as there's no real plan for dealing with climate change (most countries aren't going to meet the Paris limits), this just helps me stay a little more sane in my day to day. So, what I'd really be looking for in either an EV or PHEV is a car that can do at least some of our out-of-town road trips, that way we can limit the CRV's use as much as possible. I'm also considering the Honda Clarity PHEV and the Chevy Bolt. Though what I like about the e-Golf is:

1.) after EV tax incentives and dealer discounts, it can supposedly be purchased for less than $20K.

2.) it has a better looking exterior, a more comfortable and higher quality interior, more cargo space, and better ride and handling than the Chevy Bolt.

3.) it's a full EV, with way less parts than a PHEV, so in theory, it should have less long-term maintenance issues and costs than a PHEV (though I'm not sure if this is actually even true). Ideally, even after the battery degrades to a 90 mile range at the 8 year mark, you could get another 5 or so years out of it as commuting/grocery-store car (though this is why I was asking about the long-term dependability of this vehicle).

4.) its EPA ratings seem to be conservative - its real-world range seems to be more like 150 miles, and 4-5 miles/kWH as an all-weather average seems doable.

In my mind, the only advantage that the Chevy Bolt has on the e-Golf then is that the occasional 250 mile trip can be done in 0-1 DC fast charging stops, whereas the e-Golf would require 1-2 stops. But if I realistically couldn't take the e-Golf out of town at all, then this would force me to have to re-evaluate...

JoulesThief, that's an interesting idea you propose - doing a Level 2 charge immediately after the DC fast charge. Do you mean, though, that I would DC fast charge to 80%, then switch to Level 2 charging for the last 80-100%? Or do you mean fast charge to 80%, drive around for a a few miles, and then do a Level 2 charge? Thanks.


I would mean using the DC fast charge to take the battery to 90 or 95% State of Charge, which is fine, and then go and plug in immediately to a Level 2 charger in the same location, and fill up that last 5% in 25 or 30 minutes on the Level 2 charger, so that the battery pack DOES get an equalization charge, so all the battery cells are equally recharged, before you head back down the interstate or highway again. As long as all the cells get an equalization recharge, you've done the batteries good, and you've met VW's requirements with doing an AC charge, every other recharge. You will be doing the battery good, not harm, at that point.

The last 10 minutes indicated on my dash of my 2105 SEL add hardly any Kwh to the battery pack. In the 2017, that would be the last 15 minutes of Level 2 240V 30 amp recharger.... so if you are on a trip and pressed for time, recharge to 90% on the DCFC, and then add another 20 minutes doing Level 2 recharging up to 95 to 97 or 98%, then get back on the road. Make a meal stop out of it. 30-35 mins DCFC, move to level 2, and another 20-25 minutes on the level 2 recharger.

You can discharge an e-Golf battery faster than you can recharge it. Therefore, it pays to conserve battery pack by driving 55 mph as much as possible, and not waste the time replenishing at an EVSE station, you'll wait longer at the EVSE station than the time you'll save going 55 , 60 or 65 MPH, on an e-Golf.

If your time is worth anything, forgo the political climate and nonsense, and drive the CRV on the longer trips. Time = money

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 Post subject: Re: DC fast charging the 2017 e-Golf twice, back to back
PostPosted: Tue May 01, 2018 7:48 am 
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OK, that's a great tip, thanks. For the Level 2 equalization charge, I noticed you said it can be done by only charging to 97%-98%. So this charge "balances" the battery cells even if you don't go all the way to 100%? Is there a minimum SoC or a minimum charging time you need for this Level 2 equalization charge to do its thing? Like could you fast charge to only 80%, then spend 15 minutes Level 2 charging to say 88%, and this would have the same effect of preserving long-term battery health?


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