When insuring your electric vehicle with a hired battery, you need to include the battery in the declared value of the vehicle. The insurance value of the battery is stated in your hire agreement, but it is typically around £6,500. If the car cost you £6,000 and the battery value is £6,500, then you declare the vehicle value at £12,500 and not the £6,000 you paid for it.
You must also make sure you tell the insurance company that it has a hired battery pack. They should make a note of this.
The reason why you must make sure the battery pack is insured is if you had a serious accident and the vehicle was written off, the battery agreement needs settling. The insurance company would pay RCI for the cost of the battery pack and then your agreement would end. If you didn't insure the battery pack, you'd end up continue paying for the battery hire for a vehicle you no longer owned and possibly for a battery that no longer existed!
While the hired battery arrangement did confuse insurance companies initially, most have now caught up and now fully understand the arrangement and it doesn't increase the price of your insurance. Companies like Aviva, Direct Line, LV and others are now charging low premiums for electric cars with hired batteries. One example in my own family is a Renault Zoe (with hire battery) has cost only £156 to insure, which was cheaper than the previous petrol Ford Focus.