Eletechsup 1A 1.2V 1S NiMH Battery Dedicated Charger 1.5V 3V 4.5V CC/CV Charging Module Board (1S, 1)

I incorporated this board into a product to make it rechargeable. Coupled with Eneloop batteries there should never be the need to renew them, as they are rated 2100 cycles, compared to 300 cycles for Li-Ion ones. Plus there is no associated risk to NiMh.