Hello lesfrank, I'm afraid you've asked the question in a manufacturers clinic for Wisper bikes only, so no-one will see your query. It's best if you repost it in the main electric bikes forum, here's the link for you:
Forum
Just click the blue "New Thread" button at the top to enter your query.
Meanwhile, I think this is the size of your batteries in millimetres:
100 x 101 x 86
and this size has been extremely difficult to get of. However, someone did find one source here:
SLA supply
.