Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
Coupon (27.45 USD): BGTorch4
(CouponsFromChina.com tip: this code has to be applied in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): 8d9793, CMB3, BCNLXK, BGFLS15, BGAFF10OFF, BGCuponation10, 4BLF, BGHONEY2110, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, BGFLBA, BANGGOODSD, 6GSGIT
(there’s a little possibility that old coupon will work)
Price history and price alert
Do you need price history chart (for all/most countries) for 2x KeepPower P1835J 18650 3500mAh Battery? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).