High mileage but young ... what is the battery risk?

[bkgee]

Hello and thank you for this forum! I'm looking at purchasing an e-Golf and trying to wrap my head around all the variables.

One variable in particular is the HV battery. From all of my searches so far it seems that the e-Golf battery is a reliable long life component and not many have been replaced on warranty. I plan to ask any potential seller if I can drive a full cycle on a car before I buy it, so that I can verify the state of health / degradation.

I'm looking at a very high milage car with 150,000 miles. It's a 2019, so not really old, just very high mileage. Probably a frequent long commute... Here is my question for the forum - does the high mileage alone pose a concern regarding battery degradation? or is degradation much more a factor of age?

I would need to travel quite a bit to look at this car, and have quite a long first EV drive home too. So trying to consider the battery issue thoroughly before I commit. If there is no particular reason the battery would have higher degradation than a much lower mileage example of the same year, then this older car could be a much better deal at almost half the price of other 2019s I'm seeing.

Thanks in advance, much appreciated!

 

[f1geek]

Hello and thank you for this forum! I'm looking at purchasing an e-Golf and trying to wrap my head around all the variables.

One variable in particular is the HV battery. From all of my searches so far it seems that the e-Golf battery is a reliable long life component and not many have been replaced on warranty. I plan to ask any potential seller if I can drive a full cycle on a car before I buy it, so that I can verify the state of health / degradation.

I'm looking at a very high milage car with 150,000 miles. It's a 2019, so not really old, just very high mileage. Probably a frequent long commute... Here is my question for the forum - does the high mileage alone pose a concern regarding battery degradation? or is degradation much more a factor of age?

I would need to travel quite a bit to look at this car, and have quite a long first EV drive home too. So trying to consider the battery issue thoroughly before I commit. If there is no particular reason the battery would have higher degradation than a much lower mileage example of the same year, then this older car could be a much better deal at almost half the price of other 2019s I'm seeing.

Thanks in advance, much appreciated!

HV battery degradation is function of calendar age as well as charge cycles, and pack temperature also interacts with these two variables, higher temperatures being bad for cell health. You are located in Reno where it is not too hot, but I don't know where car is for sale. The way to mitigate high temps is to keep pack at less than 100% SOC for more than a few hours at a time. Remember also that the VW engineers who designed the e-Golf were conservative in their specifications, even though the pack does not have active thermal management, a feature of any mass produced EV sold in the USA except for the Leaf and e-Golf.

150,000 miles is a ton of miles which means a lot of charge cycles. Assuming car was purchased 5 years ago and driven 50 weeks a year, 5 days a week, that works out to 120 miles a day, on average. This car was charged at least once a day since its rated range when new is 125 miles, though the good part is that the car probably never sat at 100% for days on end, which is bad for the cells, too. Let's say the car was charged twice a day, so that is 2500 charge cycles so far. We will assume car was charged mostly on AC, which tends to gentler than DCFC, but temperature also plays a role here. I have been keeping track of my car's SOH (state of health) and it has ~70,000 miles now. I am estimating it has about 90% SOH. Using the data I have for degradation over the past ~1100 charge cycles, I would estimate this car has about 25 to 26 kWh usable capacity, and compared to new, assuming 25 kWh, that is about 79% SOH. With an as new EPA range of 125 miles, that is 99 miles of range (that is driving the car from 100% to 0%, which most people wouldn't do). Remember, this is an estimate.

If you can take the car out for a spin on the highway doing 65 mph, that is 1.5 hours of driving to test the range (charge to 100% and drive till about 10% and don't get stranded). Or you could plug in an OBD dongle and use Car Scanner to look at what the BMS thinks the usable capacity is.

Can you live with a car that you can drive about 85 miles before you need to charge it?

 

[bkgee]

Thanks f1geek, much appreciated,

After I wrote my post, I kept thinking about what I've learned, and came close to your conclusions but without the supporting detail. A full drain and charge every day at minimum, and risk of routine DCFC charges.

I'm not sure I will travel to Palm Desert CA just to test this car, but it's not out of the question yet. Maybe a conversation with the sales person first.

To your question, I think 85 miles is on the low side of my hopes, but in reality would fit 90%+ of my use cases. Reno is a small town and my commute is 25 miles round trip.

I would love a Golf that I could easily take on long range road trips (why I've also been looking at TDIs) but want and need a car that can save me thousands of dollars a year - in which case I suffer using my full size pickup for the road trips. I test drove an eGolf yesterday in Sacramento (yes I drove 4 hours round trip on a data collection mission) - I actually love the car quite a bit, and it makes me not really want to deal with a TDI's engine and transmission oils, differential oils, break downs/repairs, etc etc.

 

[f1geek]

Thanks f1geek, much appreciated,

After I wrote my post, I kept thinking about what I've learned, and came close to your conclusions but without the supporting detail. A full drain and charge every day at minimum, and risk of routine DCFC charges.

I'm not sure I will travel to Palm Desert CA just to test this car, but it's not out of the question yet. Maybe a conversation with the sales person first.

To your question, I think 85 miles is on the low side of my hopes, but in reality would fit 90%+ of my use cases. Reno is a small town and my commute is 25 miles round trip.

I would love a Golf that I could easily take on long range road trips (why I've also been looking at TDIs) but want and need a car that can save me thousands of dollars a year - in which case I suffer using my full size pickup for the road trips. I test drove an eGolf yesterday in Sacramento (yes I drove 4 hours round trip on a data collection mission) - I actually love the car quite a bit, and it makes me not really want to deal with a TDI's engine and transmission oils, differential oils, break downs/repairs, etc etc.

Palm desert is very hot. That puts extra stress on the battery. Best of luck with your decision. You could ask for a photo of the dashboard showing SOC and estimated range - this is not ideal information because the GOM (Guess O meter) is based on recent driving, but at least it is some indication of pack SOH. Or if it is a VW dealer, you could ask for a pack health test.

 

[bkgee]

I'll look into the pack health test - thanks for the tip!

 

[mpulsiv]

I wanted to give more insight about calendar years that “f1geek” mentioned.

Battery age is something to consider. Someone reported 3% degradation with OBDeleven just for letting a battery sit idle (e.g., 0 miles clocked in 12 months). Let this sink in for a moment. Car hasn’t been driven for a year and you naturally lose 3%.

 

[f1geek]

I wanted to give more insight about calendar years that “f1geek” mentioned.

Battery age is something to consider. Someone reported 3% degradation with OBDeleven just for letting a battery sit idle (e.g., 0 miles clocked in 12 months). Let this sink in for a moment. Car hasn’t been driven for a year and you naturally lose 3%.

It is possible, but will vary by car. For example, Hyundai Ioniq batteries may lose only 3% after 10 years and 100,000 miles.