You can contact grin at
https://ebikes.ca/product-info/grin-products.html
I ride ebikes and they are excellent for off gridders but I don't mess with home built batteries.
There are a lot of risks charging LI and Ebike batteries usually associated with DIY or blackmarket batteries and parts.
To many fires and explosions causing serious harm so know the dangers and I would suggest ordering a UL approved battery.