Currently, the best rechargeable C-size battery is the ELB 5000 Battery. A pack of 6 costs $24.

About C-Size Batteries

Although they are no longer as popular as they used to be, C-size batteries are one of the most common alkaline batteries today. They have kept the same dimensions (50 millimeters by 26.2 millimeters) since 1926 and are used in medium-drain electronics such as toys and instruments. Disposable 1.5V alkaline dominated the C battery market for years due to its high capacity and long shelf life.

Rechargeable C-size batteries are rapidly gaining marketshare over their throw-away counterparts, thanks to crucial technological advances within the past decade. Instead of alkaline, they are using 1.2V Nickel-Metal Hydride Chemistry (NiMH) that allows for greater capacity that doesn’t atrophy after long stretches of inactivity. Whereas in the past rechargeable batteries would drain by themselves via discharge even when they weren’t in use, they now retain up to 85% of their charge capacity for months at a time. No more pulling out a rarely used flashlight the night before a camping trip only to find that the charge has evaporated in your garage.

Of all the rechargeable batteries on the market, ELB offers the best C-size battery. The 1.2V NiMH cells have a 5000mAh capacity, almost as much as the standard 8000mAh of disposable alkaline batteries and much higher than other NiMH cells, and close to the capacity of a lithium cell.

For a charger, I recommend the Maha PowerEx MH-C808M. This smart device can charge 9 C-size batteries at a time.