You sound clued up on Zoe battery leasing so I’ll take your word for it. I don't suppose you have a link do you? I’d prefer the Zoe. Unfortunately it looks like Renault UK have removed the detailed information on leasing options and buyout, and now simply state that leases start from £25 per month.
When I looked into it a while back most people - including the current owner of that car - opted for the ~£50 per month lease. The cost of buying out the battery lease at that time was a sliding scale based upon age, and I think was £1600 on the 7 year old car I was looking and would be £1100 two years later.
I wouldn’t be surprised if the asset value of the battery is written down based upon the monthly payment and once the total of monthly payments reach or exceed the original value of the asset then the ownership may be transferred to the lease for a nominal cost plus admin costs. That wouldn’t be unusual.
Again it wouldn’t be unusual for the lessor to terminate a lease agreement early if the lessee forward paid the balance of the agreed term. When this happens then the lessor may allow ownership of the asset to be transferred if doing so would meet the cost of the value not yet written down.
The only current information I can find is on the Renault Group website (below). The £150 per month iou mentioned would far exceed the cost of the unlimited annual mileage option, which at €124 per months is around £103 per month. The €69 (£57) option for 7500km (4600 miles) looks like the ~£50 pm option
Source:
All you need to know about recharging the Renault ZOE - Renault Group