Hi flecc, thanks for your response.
I've seen batterys on ebay, but they ask that you state the model for the battery, and that's what I don't know. eg:
POWABYKE BATTERY ALL MODELS 15AMP BATTERIES NEW CASE on eBay, also, Bikes, Cycling, Sporting Goods (end time 25-Jun-08 10:13:15 BST)...