Battery SoH - Official manufacturer reports

cannco253

It's difficult to find information on this so I thought opening a new thread might be a good way for everyone to share information. Hat tip to AndyBoBandy for mentioning that manufacturers are probably regularly checking batteries themselves to monitor degradation, when you agree to the online T&C's you don't really know what's going on behind the scenes.

I know you can plug in an OBDII and use an app for most cars to scan the battery, but I'm wondering what different manufacturers provide to owners following an official battery check, if anything at all. I still don't understand why they make this difficult for owners to find out given that it's the first thing you would check on a secondhand EV purchase. On a slightly different note, has anyone ever used an OBDII to check out a secondhand ICE car before buying one in the past?

I've had a Nissan Leaf battery report (image in the link below) which I thought was very poor. When the car was in for it's most recent service I asked the mechanic about the battery report and he agreed that it was hardly worthwhile doing, and advised met to get an OBDII. The dash and report does show you the battery capacity across 12 bars, the first bar being 15% and each subsequent bar 6.25% which while not great is some information.

https://mynissanleaf.com/viewtopic.php?t=20823

VW are providing battery reports for ID cars (partial screengrab below). At least this shows some figures, would be good to see the full report. AFAIK there is no way to see the SoH through the in car software and nothing is displayed in the dash.

https://insideevs.com/news/548404/volkswagen-confirms-8percent-degradation-id3/

zg3409

There is a good chart here for Nissan leaf

https://pushevs.com/2018/03/20/nissan-leaf-battery-degradation-data-24-vs-30-kwh-batteries/

I remember seeing an official Nissan chart based on more data, but it's similar.

Most manufacturers & dealers won't share exact degredation with customers, as it may drive warranty claims. The other thing is most if not all have a hidden extra buffer which may or may not be used up over time to make the battery appear better for a longer time. Even tesla puts "long range" batteries into some standard range cars, as it will result in less warranty claims and owners can software switch to larger battery.

Nissan had a software fix to display less lost capacity, which makes no sense, they claimed it was calculated wrong before and the correct figure was higher.

We really cannot trust manufacturers to truthfully display and measure left capacity. Even the BMS won't really know the capacity unless car is run down to say 5% and charged up again. Even then actual capacity depends on temperature and how fast battery is discharged. In theory a discharge from 100% to 0% in a controlled environment is needed. I am sure all manufacturers collect data during servicing, and use that data to factor in future warranty claims. I for one don't trust any of them. My ioniq 28kWh with 70,000km on the clock reports "100%", no degredation which is not physically possible, they only start reporting degredation at over 160,000km which is the battery warranty limit for newer cars. (My one has 200,000km warranty.)