Found my battery's aging %, seems low -- or is it?

bizzle · **Joined:** Thu Oct 29, 2015 7:34 pm **Posts:** 370

Was anyone able to figure out where to look with a VCDS? I have one, but haven't bothered hooking it up since last year (and the software was still in beta in regards to eGolfs). I might hook it up today but wouldn't know where to look.

phr00t · **Joined:** Wed Oct 07, 2015 6:35 am **Posts:** 43

I purchased a Bluetooth OBD2 reader & am trying to find out how to gather the battery "state of health" with it. It would be great to see how the "state of health" has decreased over my eGolf's life. There are a bunch of Android apps that read OBD2 data, but none are great for electric vehicles... except "Leaf Spy", which is specifically geared for the Nissan Leaf. Torque Pro has a "PID Scanner", which scans for OBD2 values -- one of which is probably the data I need to get the "state of health". Unfortunately, there are a ton of PIDs and I don't know how to track down the right one. I wonder if any of the numbers from my earlier post might help.... the PID is 4 digits, I think.

Anyway, wondering if anyone else found their "state of health" successfully via any means, or have tips on how I could go about finding mine with this new OBD2 scanner & an Android phone.

vetaldj · **Joined:** Fri May 01, 2015 3:20 pm **Posts:** 86

Well, back to forum after quite some time.

Sorry I was not able to check this out yet. Today/tomorrow I will connect it one more time and will see what I can find. Will post later on.

schleppy · **Joined:** Wed Jan 25, 2017 7:06 pm **Posts:** 60

Has anyone paid for JUST a battery check up? I have no intention of having the dealer do any work on my e-Golf unless they need to, but I want to maintain the battery warranty, and they are the only ones that can "check" the battery. Has anyone had any luck getting just a battery check up done? If so, how much?

f1geek · **Joined:** Fri Jan 23, 2015 1:18 pm **Posts:** 281

Good luck getting a battery capacity number from an official source. I asked at my local VW dealer and they said they weren't able to provide that information. A month later, I talked to VW rep on the phone and they informed me that VW doesn't "have the technology" to provide that information. After a lot of arguing, VW finally relented and told me a dealer could do it, but it would require leaving my car from several days to a week for the dealer to perform tests. All of these responses seem ridiculous to me as there is no way the car can provide a range estimate if the BMS doesn't know the usable capacity in real time. VW and its dealers just don't want this information made available.

I have been trying to keep track of my battery capacity over the 2.5 years I've driven the car. I have about 20,000 miles on the car now. I have found that the estimated usable capacity is highest at a high SOC and decreases as the SOC approaches 0%. Last July with an SOC of 19%, the estimated usable capacity was 19.5 kWh. Last September, at 19% SOC, the usable capacity was 19.3 kWh. This January at 19% SOC, it was 19.5 kWh. Yesterday, at an SOC of 20%, the usable capacity estimate was 18.3 kWh.

So, it looks like my car lost about 1kWh of capacity (about 5%, assuming 20.5 kWh initial usable capacity) since I began tracking the data.

vetaldj · **Joined:** Fri May 01, 2015 3:20 pm **Posts:** 86

Got some time to dig in VCDS. Well, I did not find magic number or settings yet. What I found is ability to see each cell's voltage. My car has 88 cells with 3.51-3.54 range on each. Car was not charged though. Will review this one more time. Knowing max new voltage and having this number can help us get SOH number, maybe. Need to review each cells' voltage when car is fully charged to see what it will be.

Found bunch of interesting info, history, total kWtt charged, total miles driven etc. But nothing close to state of health.

Will continue digging and will send my file for battery module to Ross Tech so maybe they can get some useful info for us soon.

miimura · **Posted:** Thu Jul 13, 2017 10:08 pm

Voltages don't tell you anything about SOH. They only tell you about balance and SOC. When the battery ages or degrades, it delivers a different amount of energy between V2 and V1. So, you have to find out how much energy passes into or out of the pack while it's in use. This is called Coulomb Counting. The car keeps track of this in order to have accurate SOC at any instant and SOH over time.

JoulesThief · **Joined:** Mon Oct 05, 2015 2:01 pm **Posts:** 2021

miimura wrote:

Voltages don't tell you anything about SOH. They only tell you about balance and SOC. When the battery ages or degrades, it delivers a different amount of energy between V2 and V1. So, you have to find out how much energy passes into or out of the pack while it's in use. This is called Coulomb Counting. The car keeps track of this in order to have accurate SOC at any instant and SOH over time.

Speaking of counting Coulombs, have to done a recent battery degradation sample on your e-Golf?

miimura · **Posted:** Fri Jul 14, 2017 10:02 pm

JoulesThief wrote:

miimura wrote:

Voltages don't tell you anything about SOH. They only tell you about balance and SOC. When the battery ages or degrades, it delivers a different amount of energy between V2 and V1. So, you have to find out how much energy passes into or out of the pack while it's in use. This is called Coulomb Counting. The car keeps track of this in order to have accurate SOC at any instant and SOH over time.

Speaking of counting Coulombs, have to done a recent battery degradation sample on your e-Golf?

No. Not since the last set in May.

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Found my battery's aging %, seems low -- or is it?