CANADA, so idealy a Ca retailer, or at least north american. Might look at battery space for starters. I'm not sure if the scooter places like monster and others are carrying lithium yet.
Sorry I missed the location. I've been extra dumb lately. My dad survived, but he's still in hospital. So I'm not mentaly all there lately.
I'm also confused by the use of one 16v battery in the string, but it's very likely that a 12v one could be substituted as far as running the scoot goes. It's charging where it gets tricky.
However, that opens up another possible problem, since you would then be likely to overcharge the whole thing by 4v unless you got a new charger for "48v".
The possibility exists that your charger is a "48v" charger, and you've been undercharging all along. A voltmeter may be able to tell you what the output voltage of your charger is, and verify that a 12v replacement will work or not work.
Then we still don't really know what to suggest you buy untill we know what kind of lithium polymer battery you have. It could be lico, limn, or lifepo4. Each would have a slightly different end of charge voltage. Personally, I hate this shit where you get a battery and only know it's "lithium" and nothing else. The retailer refusing to help you makes it even worse, but that scoot could have been sourced straight from china leaving the CA retailer perplexed about it.
What to do? I'd cut that sucker open, and hope to see labels on the cells themselves. Then you could at least know what chemistry to look for in other brand names. Since the end of discharge voltage varies so much between lico and lifepo4, you really can't just swap in lifepo4 if you have lico.
Maybe you get lucky and find a broken wire inside and vilola it's fixed!!
In addition, do a search of all relatively nearby wheelchair battery sellers online, looking for the same brand. I came up empty on a quick search, but maybe you can dig deeper and find the same brand and size.