RE: Do Renault now sell their batteries?
£300~£400 per kWh is about the going rate.
Bear in mind that we do not know the actual capacity of the Renault batteries. I saw an early press item in which Renault let out that they were using only 70% of the batteries capacity. That would make it, actually, a 31kWh battery if that is what they actually decided on.
It makes sense if you look at the masses - Fluence battery pack is 260kg, Leaf is 200kg. So we might be looking, instead, at 22kWh of a 31kWh battery pack being used in the former, and 21kWh out of 24kWh for the Leaf (this is no secret).
Nissan quote the actual battery pack size rather than the usable capacity, whereas Renault do the reverse. This would help explain why Nissan say in their handbook and warranty conditions that the Leaf pack should not be routinely charged to 100%, and, apparently, they provide a 'helpful' 80% charge 'limiter' that you can set when you plug it in for a charge. No such limitations on Renault batteries - and yet they are leasing and therefore remain the owners so should be the more risk averse (whereas it is the Leaf owners that should be more concerned, yet Nissan seem to want to give them this helpful advice).
I reckon Renault batteries are actually 30kWh packs to help with long-term life, and also as they degrade they have probably set the software to eat into the reserve capacity, for a while, thereby giving the impression that the pack last longer. ... It's just a hunch, but just consider the battery pack mass, and it explains the apparent cost discrepancy.
The other cost difference is that Renault batteries have some form of active temperature management (TMS) in them, whereas Leaf doesn't have any (very bad!).
Say £250/kWh [for the sake of argument] x 31kWh = £8k + £1k TMS?
For Leaf x 24kWh = £6k
This is all just a hunch....