I have said this many times before. This is the only car I have ever had that can fix itself. I can't count the times I have had warning lights, and the next day they are gone.

 

That's a strange but positive sign. A bad battery module doesn't usually fix itself. It's possible the car's battery management system has rebalanced the cells, which can sometimes mask a weak module.

Don't trust it completely yet. Keep monitoring the cell levels, especially after a high charge. The problem could still reappear.

 

So this is at 90% charge

 

this had my light on

 

I will try to run at 90% for next few days, maybe get brave enough to charge 95 again. Will also screen shot the 80% cell balance when I get a chance

 

I think this one was my worst

 

I imagine it like I have a flashlight with four batteries in series: three AA and one AAA.

What I notice is that if the ID4 pack is top-end balanced, then all the cells reach Full together. Which looks nice on the car scanner app graph when the pack is "full". But then during discharge, the weak one reaches low-voltage cutoff sooner. So it doesn't help at all that all the other cells still have some usable charge.

But the pack can instead become bottom-balanced, so that the cells all reach low cutoff voltage together. But then, during charging, the weak cell will reach full-charge voltage faster, and charging will end, leaving the other cells less than full.

Either way, the result is the same: the total power available is the capacity of the weakest cell, times the number of cells. In the "flashlight" example, that like having four AAA cells in series. It'll work just fine, but some of the capacity of the healthier/bigger cells is "locked out"

It sounds like maybe your pack is balanced at full; but could still be unbalanced at low SOC

 

I have two questions. First, how do you get a scan of battery modules? Second, if individual modules go bad, can they be replaced? Thanks.

 

Individual Cells cannot be replaced by VW. Individual Modules can. My 2021 is in the shop now having one module replaced because a singe cell in that module is 0.02V lower than the highest cell. Here is the last photo that the dealer sent yesterday. They are replacing 1 of the 12 silver modules inside the battery pack under warranty.

 

how do you get a scan of battery modules?

Get a $30 dongle and the free car scanner app. That is what produced the bar graphs above. The figure that matters is the deltaV (difference between the highest and lowest cell voltage.)

if individual modules go bad, can they be replaced?

Yes a number of people here have had one module go bad and replaced under warranty, see:

https://www.vwidtalk.com/search/468171/?q=module+bad&c[showFilter]=visibleOnly&o=relevance

 

Get a $30 dongle and the free car scanner app. That is what produced the bar graphs above. The figure that matters is the deltaV (difference between the highest and lowest cell voltage.)

Yes a number of people here have had one module go bad and replaced under warranty, see:

https://www.vwidtalk.com/search/468171/?q=module+bad&c[showFilter]=visibleOnly&o=relevance

Lol, I know this one Muppet on here, called Yevgeniy, that had to replace his out of warranty

 

Dropping the battery is one thing. Getting it back up with the bolt holes lined up quite another. The lift table is priceless.

 

Here is the ID3 video. He had to drop the battery because the Pyro fuse had blown. The battery work is about halfway in.

The lift table he is using seems undersized to me.