DC fast charging the 2017 e-Golf twice, back to back

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Kieran973

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Joined
Apr 18, 2018
Messages
16
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?
 
Kieran973 said:
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?
 
"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....
 
Kieran973 said:
"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.
 
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.
 
Kieran973 said:
"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.
 
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....
 
"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.
 
Kieran973 said:
"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
 
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?
 
Kieran973 said:
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?


IMHO, watching LiPo batteries recharge for radio controlled toys and ham radio's, you should strive let the charger FINISH balance recharging to all cells at either 4.05V for a 90% SOC or 4.20 V for a 100 % SOC.

I would take the DCFC up to an indicated 90% SOC, and then, I would put the car on the Level 2 Charger and run it for 20 to 30 minutes, which should add another 2 to 3 kwh to the battery pack, or close to it. You want your "gauge" needle to finish up somewhere from all the way full, to half a tick down on the fuel gauge, after completing the level 2 charge portion. The next recharge, let the car do a full complete to the top of the gauge level 2 balanced recharge.
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If any of you are going to charge to 100% SOC, you should do ti very rarely because keeping the cells at 4.2 V (especially at ambient temperatures over 90 F) will kill them over time. Keep your pack at 80% or 70% at most to get the most life out of all the cells. Balancing the pack is MUCH less important than keeping the SOC well below 100%. But if you want to degrade the pack quickly, by all means, continue to charge to 100% on a daily basis.
 
f1geek said:
If any of you are going to charge to 100% SOC, you should do ti very rarely because keeping the cells at 4.2 V (especially at ambient temperatures over 90 F) will kill them over time. Keep your pack at 80% or 70% at most to get the most life out of all the cells. Balancing the pack is MUCH less important than keeping the SOC well below 100%. But if you want to degrade the pack quickly, by all means, continue to charge to 100% on a daily basis.

VW does not charge to 4.2V on their battery packs. That is for illustration purposes only on RC batteries. VW recharges their batteries to about 91%SOC, which is when your fuel gauge indicates that the 'tank' gauge is 100% full.

So the most you can put into that e-Golf battery is 91%.

My e-golf gets charged until the EVSE shuts off, almost every single time it gets recharged. The gauge reads full. I currently show 117 miles of range per recharge, off from 129 mile per recharge, when the car was new. 31 months with the e-Golf now, and 16200 miles. I'd say that's pretty normal degradation.
 
Losing 10% SOC in less than 3 years and 16,000 miles is the result of you fully charging the battery pack and letting it heat soak. If you set the charge limit to 70% or 80%, the cells will degrade much less. “Balancing the cells” regularly is unnecessary and damaging. I’d much rather have less degradation and balance the cells once a year for my yearly long trip when I charge to 100%. VW lets you choose a max % SOC because VW knows you’ll quickly kill the pack if you insist on 100% charges every day.
 
Hi f1geek,

I don't yet own an e-Golf, but I was under the impression that VW required owners to follow every DC charge with an AC charge, otherwise the battery warranty would be "voided." Are you saying this isn't the case? Or that this is the case, just don't, on that follow-up AC charge, go all the way to 100% -- only go up to like 70 or 80%?
 
f1geek said:
Losing 10% SOC in less than 3 years and 16,000 miles is the result of you fully charging the battery pack and letting it heat soak. If you set the charge limit to 70% or 80%, the cells will degrade much less. “Balancing the cells” regularly is unnecessary and damaging. I’d much rather have less degradation and balance the cells once a year for my yearly long trip when I charge to 100%. VW lets you choose a max % SOC because VW knows you’ll quickly kill the pack if you insist on 100% charges every day.

Get back to me when your battery on your 2017 is 3 years past the build date. By 18 months, my range was down to 121 miles. By 30 months it's down to 117 to 119. None of my charging methods, or limits or techniques have changed. I don't ever charge to 100%. VW makes the charging levels achieved on their battery packs such that with what they show as a "full" recharge, will get the battery through the warranty period. I'm not worried, at all. My battery seems to be losing capacity a lot slower than it did in the first 12 months.
 
The manual says to avoid "frequent and consecutive" DCFC sessions and also says to follow every DC charge by an AC charge. I believe the manual says to alternate DC with AC to reinforce the point about not consecutively DC charging. I believe this instruction has nothing to do with balancing the pack (there is ZERO mention of balancing the pack in the manual, as far as I can find, so I think "balancing the pack" is BS, as far as VW is concerned) but has everything to do with the pack temperature. If you consecutively DCFC the pack will get hot, and the combination of high temperatures and high SOC is what rapidly damages lithium ion batteries.

Why do you think all EVs except for the Leaf and e-Golf have TMS? Have you read about how Arizona Leaf packs were destroyed and Nissan had to redevelop the battery? Of course, I think even revised 24 kWh, 30 kWh and maybe even 40 kWh Leaf packs have the wrong chemistry because they degrade too fast (no data on the 40 kWh pack yet) and I suspect even having TMS with the existing Nissan chemistry wouldn't help that much. Once Nissan switches to LG Chem for their cells, and adds TMS then I think the pack durability will get much better. Maybe VW doesn't sell a lot of e-Golfs in a lot of hot places, but then again, Southern California can get pretty hot for a lot of the year. If you look at e-Golf sales vs Leaf sales, I suspect the vast majority of e-Golfs are sold in the higher latitudes (Northern Europe), so high temperatures are generally not seen by these cars. VW doesn't even sell the e-Golf in all 50 states, thus limiting the e-Golf exposure to most of the southern US where the pack would get beat up by high temperatures.

One of the benefits of having a large pack is rarely needing to charge to 100% SOC. Avoid charging to 100% regularly. Again, high SOC and high temperatures are BAD for the cells. If you need to charge to 100% all the time, then you need a BEV with a larger pack (Bolt, Model 3, etc.).

As far as voiding the warranty, you are going to have to figure that one out because it's not clear to me.
 
Isn't there a software "cushion" where an indicated 100% charge is actually more like 80% already? (24kwh battery pack with usable charge capacity more like 19-20kwh?)

I have read through the manual on charging at least 2 or 3 times now and yes, VW is very clear on no back-to-back DC charging. Nowhere do they suggest not charging to 100%, but they do advise not to leave it charged at 100%.

Not questioning your opinion because it sounds like you have an engineering mind, just seeking clarification.
 
msvphoto said:
Isn't there a software "cushion" where an indicated 100% charge is actually more like 80% already? (24kwh battery pack with usable charge capacity more like 19-20kwh?)
The cushion is nowhere near this much. In my experience charging the 35.8 kWh battery on my 2017, the "fuel gauge" encompasses around 34 kWh, which is about 95% of nominal capacity.
 
There is cushion, but it's mostly at the bottom of the SOC, not the top. OK, I'll clarify my warnings before: 1. ANY temperature and very low SOC are BAD for the pack. 2. High temperature and high SOC are BAD for the pack.

The e-Golf gives a lot warnings as the pack gets near the bottom, and cuts power, eventually shutting the whole car off if the SOC gets too low - and flashes instructions to charge immediately, because at any temperature a low SOC is very bad for the cells. If the pack gets too hot, you'll see the power needle move and find that charging speeds reduce - both of these reduce the current flowing in the pack and thus decrease heat generation in the pack to keep temperatures in check, as there is no TMS to remove heat.

My philosophy with the 2017 e-Golf is that I want the pack to last for 10 to 15 years and still be able to get me at least 100 miles on a charge, and because I don't need to use more than half the pack on a daily basis, I will do whatever I can (within reason) to keep the cells in their "goldilocks" zone so degradation is limited.

Yes, the I believe the e-Golf does not allow the cells to reach 4.2V (the theoretical maximum - though depending on cell chemistry, this value will be different)when the fuel gauge says full (100%), based on my experience with a 2015 e-Golf. After 2000 miles, I have yet to charge the pack to any higher than 80%, so I don't actually know how high the voltage reads at a full fuel gauge.

VW went with Samsung SDI's 37 Ah PHEV2 prismatic cells for the 2017 e-Golf. If you can find the specs on this cell, then you can get a better idea of actual 100% SOC and better understand how that relates to a full fuel gauge, if you have an OBD2 reader.
 
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