@osbrook definitely NOT on a Twizy. And to be honest, after my new battery from Renault, with all updated SW from my battery melting incident, the PowerBox logically came after and I am not changing a thing - the situation is as ideal as it gets (2012 Twizy, new battery in 2015 and PowerBox = FUN). Having both now I get to look at both sides of the situation... However it goes to show the traps the dealerships set up for you.
There is nothing in the vehicle that I know of that can give you the BMS version.
I am looking for the procedure used to measure the capacity of a Renault battery. The only method is what I stated with Electrocity - calibration could be questioned however. And you can't put a fast charge on a Twizy in that scenario that I know of. For the Zoe, you have the BMS showing % charge vs the incoming measured KW being uploaded into the car's battery - that seems a good way to get an indication of capacity. Range which varies on driving style and temperature is not a good method of determining capacity either, even though it would be an indicator as it would naturally be lower. Thus seeking a scientific method is key for a claim.
Additionally, unlike a Twizy where you only have bars of remaining charge, the Zoe has % battery left. It has been shown that the car still can drive and has power at 0%. This means that "true" calibration of charge to capacity is not a real measure of what you really have in the battery.
On the contractual side. The 75% of usable capacity guarantee from Renault maybe hard to claim given it is their tools and methods that would determine it. This is obviously a conflict of interest, unless there is full transparency with an independent audit of the methodology/code. For now, collecting the procedures and understanding the BMS capabilities and logic is needed to determine how to have a true measure of your battery's status, and how it will stack up to a claim at 75%.
I don't see an easy answer here unless Renault spills the beans on how it is done. Just getting a BMS update is a push in some cases (seen videos in Spain that show frustrated owners not getting their BMS updates due to lack of tech knowledge and incompetent dealerships). The warranty holds up for full failure, but can you measure capacity is the real problem... @kennethnilsen69 - do you know or have any insights on this for the Twizy?? Given you know much about the programming of its ECU