Why do we need to "re code" a new battery, what does it do.

[G-A-R-Y]

I've heard so much about the need to recode a replacement battery, is there a need, what does it do?
Surely it's just a "dumb" battery. And what needs coding??
2023 Crafter 177

 

[Pauly]

It resets the charging regime and tells the van to relearn the state of charge of the battery etc

It’s not ultra critical as the van will adapt to it after it’s been driven X amount of times, it’s more important if you change the capacity of the battery as the van may get a bit confused over state of charge etc if it thinks the batt is a different capacity than it is

 

[G-A-R-Y]

It resets the charging regime and tells the van to relearn the state of charge of the battery etc

It’s not ultra critical as the van will adapt to it after it’s been driven X amount of times, it’s more important if you change the capacity of the battery as the van may get a bit confused over state of charge etc if it thinks the batt is a different capacity than it is

So what if you remove the second factory auxiliary battery (AGM) and associated relay and replace it with a B2B and lithium. That's what I've done, it all appears to be working great. The van is VW Grand California.

 

[Pauly]

I’m not sure
Does the factory second battery have a shunt on the negative terminal for the van to measure state of charge ?
If it doesn’t then the van doesn’t measure state of charge of the battery

 

[G-A-R-Y]

It does have a basic shunt, it shows what's going in and out, this allows for time remaining to be displayed on the VW camper panel display. Sometimes it shows 60 hours remaining, sometimes it shows 15 mins, very inaccurate although lithium voltage of 13.5v being shown. I've been testing for a few weeks and all is well despite my lithium being under the bonnet. It's gets warmer there than when used on a Sprinter. Once out of warranty I'll relocate to under the seat.
Thanks for good advice.