Battery degradation

[alexecar]

Hi,

I drive a 2016 e-Golf SE and have reached 23 months and 22k miles of my 36 month/36k mile lease. I do notice a degradation of battery, and my 60 mile round-trip commute is starting to get close if I drive the speed limit. I know that I can drive more conservatively, but I like to arrive quickly ;-)

After today's drive, the car showed the following statistics "Since charge":

Distance 60 mi
Time 1:06 h
Avg speed 54 mph
Avg consumption 3.6 mi/kWh
Remaining distance 6 mi

Temperature here today is 46-60 F

Calculating the total battery capacity based on this: 66 mi / 3.6 mi/kWh = 18.3 kWh
Percentage from original capacity: 18.3 / 24.2 = 75.8%

I understand that the e-Golf has a 70% capacity battery warranty, so I still have 5.8% to go lower.

Here are my questions:
- Is there a more accurate way to get the current battery capacity, what does VW use to check for warranty claims? I have a OBD2 tool for VW cars, if this is necessary.
- Any other experiences with battery warranty claims, any reasons why VW would deny them even if you are down to under 70% ?

Thanks,
Alex

 

[f1geek]

The correct calculation is, assuming you have 6% left, 66/3.6/0.94=19.5 kWh estimated usable capacity. Of course, a few % difference in SOC (State of Charge) can make a difference in the calculation. Also, VW warrants NET capacity. Assuming the net capacity when new is 90%, then the starting net capacity is 21.8 kWh. Therefore, you are at 19.5/21.8=89%, not 76%. You're going to have to wait a bit longer for the degradation to hit 70% of net capacity (~15.3 kWh).

I wish there were a more accurate way to get current net capacity. I've called VW about this and they say only a dealer will provide warranty net capacity data and if you haven't reached 70% or lower, then you will probably be charged for this information. If you are able to get it via OBD, could you please post this method to the forum?

I don't have any experience with VW warranty claims, but based on the their company culture (diesel emissions cheating), I'm guessing it will be like pulling teeth to get a replacement battery free of charge. Also, if you read the warranty, VW only promises to replace the defective battery with one that has no less than 70% net capacity, so it seems to me e-Golf owners are screwed and the best range you'll be able to get with a "new" battery is 55 miles (with no charge remaining) the way you are currently driving.

The only thing you can realistically do right now is to either slow down, use less energy in the car (turn off A/C or heat) or drive in ECO mode. ECO+ will limit top speed, so you probably won't enjoy that mode.

Best of luck!

 

[miimura]

^^^ This. I could not have said it better.

 

[JoulesThief]

Averaging 54 mph means you're hauling ass to get that kind of average, including time at stop signs, stop lights, and offramps, and general street non freeway traffic. You're probably never driving the speed limit anywhere to achieve that kind of average, at least in California. You have to be driving on side streets and residential streets somewhere.

Get out of B or D3 or D2 or D1 mode, if you are using them coast a bit more, and see if your range per recharge increases.

 

[alexecar]

Thanks for all responses. Too bad there is no straight way to get battery capacity.
My commute is 29 out of 30 miles freeway, with just 2 traffic lights and one stop sign. I can get 54mph average easily without going much over 65, at least at 6am and earlier ;-)

 

[JohnCegolf]

My question is: Will the computer adjust your projected miles on a full charge based on your driving habits?
Meaning if you started to drive conservative, will the projected miles on a full charge begin to increase?
I've noticed since I started driving on the highway my miles have dropped from 92 to 60 in a matter of two weeks. I can't see another reason.

 

[f1geek]

Yes, the e-Golf's GOM (Guess-O-Meter) provides a guess of the range based on your recent driving habits. If I drive on the highway, the GOM displays a much lower range estimate than if I drive around town at low speeds. When I drove down a mountain, the range estimate was ridiculously high for a few hours before the computer recalculated based on driving on a flat road. I believe most EVs provide a range estimate this way.

 

[Spektre]

Yes, old thread here, I know, but I liked the title. I'm aware of the other threads including Estimating Battery Degradation and Have you experienced battery degradation?

Many thanks to f1geek and others for explaining how to calculate degradation. I'm going to get religious about it, but I've been lazy calculating my degradation until now. My first calculation is from yesterday:

38 miles driven @ 3.9mi/kWh, 38% remaining when I got home (from CarNet) = 15.7kWh est.

I'll keep gathering data, but it looks like I'll hit the warranty point sometime this year - I'm currently at 51,749 miles.

This should be fun...

 

[f1geek]

Thanks for the update. You will probably get a more accurate estimate of usable capacity if you drain the capacity closer to 10% (or less, if you dare). Also,there is the assumption that you charged to 100% prior to starting your trip - you may want to check the CarNet SoC at full charge, because when I charged my car to "full" on the analog gauge, the OBDII data said 96% SoC (did not check CarNet for a value).

 

[Sparklebeard]

Do you have OBD11? Based on another thread on here I did some digging and I'm currently trying to figure out the Wh figures listed on module 19.

There's some speculation that the SOH_Q and SOH_P figures somehow tie into battery degradation. I did some math here based on my cars, extrapolating out from the figures I saw listed in OBD11.

The math here seems to work out to suggest that the cars leave the factory with about 90% of the battery available for use when 'fully charged' on the battery gauge. The "Energy storage unit SOC" strongly seems to be listing the vehicles current state of charge in Wh, and this was supported not just through the math working but also observing the figure drop 300Wh (in 100Wh increments) over some period of time with the car running and me monitoring figures in OBD11.

The HV battery charge state figure matches the figure shown in CarNet, so this must be the "user facing" SOC, not the absolute cell SOC.

2019
(12/18 build plate)
2852 mi
Energy storage unit SOC: 15475 Wh
HV battery Charge State: 49.0
SOH_Q: 97%
SOH_P: 97%

[Calculated usable capacity today]: 31581 Wh (15475/49*100)
[Calculated usable capacity at factory]: 32558 Wh (31581/97*100)

2016
(08/16 build plate)
26,154 mi
Energy storage unit SOC: 15000 Wh
HV battery Charge State: 80.0
SOH_Q: 87%
SOH_P: 87%

[Calculated usable capacity today]: 18750 Wh
[Calculated usable capacity at factory]: 21551 Wh


Anyone else with OBD11 or VCDS please feel free to add your figures to this, it would be great if we did find a way to diagnose battery health without relying on the trip computer.

 

[sham]

Do you have OBD11? Based on another thread on here I did some digging and I'm currently trying to figure out the Wh figures listed on module 19.

There's some speculation that the SOH_Q and SOH_P figures somehow tie into battery degradation. I did some math here based on my cars, extrapolating out from the figures I saw listed in OBD11.

The math here seems to work out to suggest that the cars leave the factory with about 90% of the battery available for use when 'fully charged' on the battery gauge. The "Energy storage unit SOC" strongly seems to be listing the vehicles current state of charge in Wh, and this was supported not just through the math working but also observing the figure drop 300Wh (in 100Wh increments) over some period of time with the car running and me monitoring figures in OBD11.

The HV battery charge state figure matches the figure shown in CarNet, so this must be the "user facing" SOC, not the absolute cell SOC.

2019
(12/18 build plate)
2852 mi
Energy storage unit SOC: 15475 Wh
HV battery Charge State: 49.0
SOH_Q: 97%
SOH_P: 97%

[Calculated usable capacity today]: 31581 Wh (15475/49*100)
[Calculated usable capacity at factory]: 32558 Wh (31581/97*100)

2016
(08/16 build plate)
26,154 mi
Energy storage unit SOC: 15000 Wh
HV battery Charge State: 80.0
SOH_Q: 87%
SOH_P: 87%

[Calculated usable capacity today]: 18750 Wh
[Calculated usable capacity at factory]: 21551 Wh


Anyone else with OBD11 or VCDS please feel free to add your figures to this, it would be great if we did find a way to diagnose battery health without relying on the trip computer.

I have a Bluetooth OBD11 Reader. How do you find that data?

 

[JoulesThief]

Do you have OBD11? Based on another thread on here I did some digging and I'm currently trying to figure out the Wh figures listed on module 19.

There's some speculation that the SOH_Q and SOH_P figures somehow tie into battery degradation. I did some math here based on my cars, extrapolating out from the figures I saw listed in OBD11.

The math here seems to work out to suggest that the cars leave the factory with about 90% of the battery available for use when 'fully charged' on the battery gauge. The "Energy storage unit SOC" strongly seems to be listing the vehicles current state of charge in Wh, and this was supported not just through the math working but also observing the figure drop 300Wh (in 100Wh increments) over some period of time with the car running and me monitoring figures in OBD11.

The HV battery charge state figure matches the figure shown in CarNet, so this must be the "user facing" SOC, not the absolute cell SOC.

2019
(12/18 build plate)
2852 mi
Energy storage unit SOC: 15475 Wh
HV battery Charge State: 49.0
SOH_Q: 97%
SOH_P: 97%

[Calculated usable capacity today]: 31581 Wh (15475/49*100)
[Calculated usable capacity at factory]: 32558 Wh (31581/97*100)

2016
(08/16 build plate)
26,154 mi
Energy storage unit SOC: 15000 Wh
HV battery Charge State: 80.0
SOH_Q: 87%
SOH_P: 87%

[Calculated usable capacity today]: 18750 Wh
[Calculated usable capacity at factory]: 21551 Wh


Anyone else with OBD11 or VCDS please feel free to add your figures to this, it would be great if we did find a way to diagnose battery health without relying on the trip computer.

I have a Bluetooth OBD11 Reader. How do you find that data?

It's probably available if you have a Ross-tech VCDS USB hex cable and software, available from Ross-tech, for a price.

 

[Sparklebeard]

I wouldn’t go with a Ross tech interface at this point; you can get the same functionality for less with OBDeleven.

I don’t think a generic OBD reader can read the number 19 gateway status channels.

 

[HighMR]

I wouldn’t go with a Ross tech interface at this point; you can get the same functionality for less with OBDeleven.

I don’t think a generic OBD reader can read the number 19 gateway status channels.

What does that mean? If I want to purchase OBDII, what should I look for?

 

[2016golfse]

Generic OBD2 is a bluetooth enabled reader that you'll generally find on Amazon, etc. that allows you to scan codes, etc. using apps.

OBDEleven is a bluetooth enabled reader and app that is specific to VAG vehicles that allows you to do the above as well as program customizations, etc.

Ross tech = VAG COM has been around a long time and includes a cable and software for a laptop that does what OBDEleven can do and more such as live data logging. OBDEleven is the cheaper alternative to Ross tech and does what most users want/need at a fraction of the cost.

 

[eGolfJoe]

Do you have OBD11? Based on another thread on here I did some digging and I'm currently trying to figure out the Wh figures listed on module 19.

2019
(12/18 build plate)
2852 mi
Energy storage unit SOC: 15475 Wh
HV battery Charge State: 49.0
SOH_Q: 97%
SOH_P: 97%

[Calculated usable capacity today]: 31581 Wh (15475/49*100)
[Calculated usable capacity at factory]: 32558 Wh (31581/97*100)

2019 eGolf SE, 6000 miles.
I have a Ross Tech VCDS cable and unfortunately I didn't take a snapshot of what the car's values were when new. Here's my numbers taken today after 6000 miles and taken right off the charger at 100%. Note that most of my driving is freeway, and I charge before I dip into the red. Always charged L2, usually at home to 50% and then 100% at work for the return trip (48 miles 1 way).

HV Battery Charge State 100%
Battery_Charge_Condition 96.8% (note difference with above reading)
HV-EM_Energy_information-High_voltage_battery_energy_information 31100 Wh
HV-EM_Energy_information-HV-EM_high_voltage_battery_energy_info... 30150 Wh
EM_prcSoh-SOH_P 91%
EM_prcSoh-SOH_Q 91%

I have noticed that my motor power gauge is dropping sooner than it used to. Would drop before around 38%, now dropping at 43%. The battery energy numbers above must be after VW's safety buffer, but what about my SOH_Q and _P numbers? They're quite a bit lower than your numbers.

 

[Spektre]

(Old thread, I know, but thought it'd be best to keep it going rather than start anew.)

So I finally broke down and sprung for an OBDeleven - decent little device, though I wish we had more insight into the actual meaning of all the fields we're able to view.

Using all the info I'd gathered from this site, Reddit, and SpeakEV, I had finally come to the conclusion that I was below the 70% mark on battery capacity. After fully charging, I was seeing 14400 Wh in the "Energy Content of HV battery, RWB-internal deduction" field in OBDeleven. I figured this is roughly 60-64% of the nominal capacity.

At ~65000 miles, I decided to finally have the brake fluid changed, so while I was there I informed the service dept that I believed the battery capacity was low enough to make a warranty claim.

I am documenting the process more thoroughly in this thread on Reddit if you'd like to read more.

Bottom line is, although no one was able to say to me "Yes, your battery is less than 70%", the paperwork I was given when I picked the car up states that the battery is at 67% and that they are awaiting a decision from VW Regional.

Stay tuned for more!

 

[f1geek]

Thank you for the update. Does the paperwork from dealer say 67% because of your information or because of VW information?

I have always assumed 89% initial net capacity (for 24.2 kWh or 35.8 kWh pack), or 21.5 kWh, so 14.4/21.5=67%.

Sorry about your pack. I wonder if you will get a 24 kWh or 36 kWh pack. But maybe VW can still get the 25 ah cells.

Do you live in a hot climate? Used a lot of DCFC “infrequently” with L2 always used in between DCFC sessions ?

Thanks for keeping us posted.

 

[Spektre]

Thank you for the update. Does the paperwork from dealer say 67% because of your information or because of VW information?

I have always assumed 89% initial net capacity (for 24.2 kWh or 35.8 kWh pack), or 21.5 kWh, so 14.4/21.5=67%.

Sorry about your pack. I wonder if you will get a 24 kWh or 36 kWh pack. But maybe VW can still get the 25 ah cells.

Do you live in a hot climate? Used a lot of DCFC “infrequently” with L2 always used in between DCFC sessions ?

Thanks for keeping us posted.

The 67% is after exhaustive (infuriating?) tests from the dealership. They asked me to bring it in with minimal charge, then they charged it up (without measuring how much energy went in?!), then they hyper-miled it down to zero, then recharged it. They had the car a full 5 days.

I live in Scottsdale, AZ, so yeah, pretty hot . I have never, not even once, charged using DCFC. The car is my daily driver so I charge it with my L2 at home.

As of now, I still haven't heard a peep about how VW plans to proceed. I am, however, eagerly awaiting their response!

 

[f1geek]

Ok so that means OBD eleven is pretty accurate considering it matches functional testing from a skeptical dealer. What a pain they had the car so long.

Ok, so the high ambient temps explain the degradation. If you routinely charged to 100% then that also enhances deg., but still no excuse for VW to give you a hard time on warranty claim.

Best of luck. I hope you get a new 36 kWh pack!