Tracking the HVB State of Health - how much decline is normal?

[mkhuffman]

What does World Of Tanks have to do with your HVB SoH?

I have no idea what you are talking about.

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[Mach-Lee]

What does World Of Tanks have to do with your HVB SoH?

WOT = Wide Open Throttle AKA flooring it

Not World of Tanks...

 

[mkhuffman]

WOT = Wide Open Throttle AKA flooring it

Not World of Tanks...

Oh, good catch. I would never have made that connection.

 

[Mrn]

It was a joke. If you ask Google what WOT stands for, you find out many would think it's World Of Tanks.

That is how inscrutable this topic would be to a new person reading it.

 

[Kamuelaflyer]

WoT is a tank mmo game. Hence the joke. Come on guys, it wasn’t that hard. It only took me till I got to the next page to figure it out. And I’m slow.

 

[mkhuffman]

WoT is a tank mmo game. Hence the joke. Come on guys, it wasn’t that hard. It only took me till I got to the next page to figure it out. And I’m slow.

It was a joke. If you ask Google what WOT stands for, you find out many would think it's World Of Tanks.

That is how inscrutable this topic would be to a new person reading it.

Yes, it went over my head, and my reflexes were not fast enough to catch it.

 

[Sully11740]

It was a joke. If you ask Google what WOT stands for, you find out many would think it's World Of Tanks.

That is how inscrutable this topic would be to a new person reading it.

I used search box on forum to figure it out. WAY too much jargon/acronyms on web.

 

[mkhuffman]

I have a few updates.

1. The SoH of my battery has increased from 91.5% to 92%. I realize that is a small change, but still very interesting since it has been at 91.5 for quite a while. Could it be the degradation is slowing down?

2. My range has definitely decreased. I used to make the drive to work starting at 100% and arriving at between 40 and 45%. This week I arrived at 36% and the efficiency was better than normal. That is around 8% less than last year, which is pretty much exactly what the SoH is showing. 92% is 8% loss of range. Wow. The data adds up.

3. I was able to measure the HVB voltage when the battery dropped below 10% and the difference between the average and the minimum is 0.017V. Is that a problem? Seems pretty darn close to me. I say it is not a problem. See graph below.

Hopefully we can get some more responses to the poll. I will update the OP after some more miles have passed and I have some more data to add to the SoH tracking chart.

 

[DanCoon]

I just stumbled across this thread and checked mine through CarScanner. Mine is showing 94% with 63,300 miles. I have one of the earlier cars that came off the line.

 

[mkhuffman]

I just stumbled across this thread and checked mine through CarScanner. Mine is showing 94% with 63,300 miles. I have one of the earlier cars that came off the line.

Wow, that is so much better than my battery is doing. I plan to do another 100% charge today and see if the SoH improves again. I doubt it will. Probably there is some averaging going on, and one charge above 92% of 91 kWh isn't sufficient to get the SoH to change. But multiple might. Who knows?

 

[bbulkow]

The real question is how much degradation is enough to trigger warranty replacement?

 

[superdave80]

The real question is how much degradation is enough to trigger warranty replacement?

Warranty kicks in if it falls below 70%.

 

[Shayne]

I just rolled over 20,000 miles and this is actually the first time I have looked at the state of health for the battery (97.5%). This is what it looks like after 3 HVBJB replacements and a lot of back road country driving. Maybe just like humans, exercise is really good for battery SOH.

I have the L2 home charger set to 85% and charge when it gets under 50%
I have around 10 DCFC over the entire year of ownership
I charge to 100% on weekends since I do a lot of back road driving Saturday and Sunday
Car is driven daily

My HVB SOH was at 97.5% before the HVJB replacement. After the replacement it was back to 100%. Think those readings can be messed with and do not hold the same legal weight as the odometer. I mentally add 2.5% to the reading now as it was the HVJB and BECM that were changed not the battery.

 

[mkhuffman]

My HVB SOH was at 97.5% before the HVJB replacement. After the replacement it was back to 100%. Think those readings can be messed with and do not hold the same legal weight as the odometer. I mentally add 2.5% to the reading now as it was the HVJB and BECM that were changed not the battery.

You can confirm the SoH by conducting a full 100% charge. Then divide the Energy to Empty (EtE) by 91 kWh and that is basically your SoH if the battery is warm (70-80 degrees F). I did a 100% charge on Tuesday and the EtE was 84.9 kWh, which is 93%. The car is currently reporting a SoH of 92%, but I think if the car will consistently charge to 84.9 or higher, the SoH reading will increase. That's my theory!

 

[Maquis]

You can confirm the SoH by conducting a full 100% charge. Then divide the Energy to Empty (EtE) by 91 kWh and that is basically your SoH if the battery is warm (70-80 degrees F). I did a 100% charge on Tuesday and the EtE was 84.9 kWh, which is 93%. The car is currently reporting a SoH of 92%, but I think if the car will consistently charge to 84.9 or higher, the SoH reading will increase. That's my theory!

These are just my thoughts based on reading I’ve done and what (little) I know about batteries: both the SoH and EtE have inaccuracies introduced by battery cell (pouch) imbalances. In theory, deep discharge/charge cycles can reduce cell imbalances and result in more accurate readings. But I don’t think optimizing the measured numbers changes the actual SoH appreciably.

These thoughts are worth exactly what you paid for them!

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