I have just checked coupons. The lowest price I could get is 329.99 USD for 48V 15Ah for OT16 (in Banggood). It is from European warehouse! Price history, coupons and price alert are available on this page. Best price?
Latest price update (UTC time):
Banggood (329.99 USD)
Banggood warehouse is located in Europe 
. I have no active coupons for you right now. What about the price? I’m not sure about the price, coz I have only 1 record(s) in my database.
Link: Banggood product page
Price: 329.99 USD
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): OT16bry
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Aliexpress
Click here… to search for ONESPORT Electric Bike Battery 48V 15Ah for OT16 [EU] on Aliexpress
Here are coupons that you can use.
Price history and price alert
It doesn’t make sense to generate price history chart, because there is one price record which is: 325 USD.
You can set price alert (for Banggood).