Just look up 18350 batteries on amazon 2 Pcs KeepPower Flat Top 18350 10A Discharge IMR 1200mAh 3.7V UH1835P Quality High Drain Li-ion Rechargeable Lithium Battery UH1835P https://www.amazon.com/dp/B078H8V1KT/ref=cm_sw_r_cp_api_i_lAkQEb03C93C0

I’ve been using these for about a year and while their life has been reduced over that time and they need to be charged every evening, they’re still going