C Cell Batteries vs 26500 Batteries - Comparisons and Recommendations
C cell batteries and 26500 batteries are physically very similar batteries - they are cylindrical batteries commonly used at home appliances, toys, flashlights, musical instruments etc.
C cell batteries and 26500 batteries differ in chemistry type and thus their nominal voltage, capacity, internal resistance (drain type), shelf life, use and similar.
C Size Batteries and 26500 Batteries - Dimensions and Specifications
C cell batteries are cylindrical batteries with physical dimensions of 50.0 mm (~1.9685 inches) height and 26.2 mm (~1.0315 inches) diameter.
26500 batteries feature height of 50.0 mm and 26.0 mm diameter, while very similar 25500 batteries feature 50.0 mm height and slightly smaller 25 mm diameter.
Due to the better similarity to the C cell batteries, 26500 batteries are more common than 25500 batteries.
Since C batteries are larger than AA (~50.5 x 14.5 mm) and A batteries (50.0 x 17.0 mm), C batteries may be replaced by these cells using plastic size adaptor, with the loss of capacity.
C batteries are also labeled as MN1400 batteries, MX1400 batteries, 343 batteries, U11 batteries, LR14 batteries, R14 batteries, 14A batteries, 14D batteries etc.
Most common labels are C battery, MN1400, LR14, and R14.
Both C cell batteries and 26500 batteries come in several chemistries and are generally divided into primary (non-rechargeable) and secondary (rechargeable) batteries.
Generally, C cell batteries are Nickel Cadmium (NiCd), Nickel Metal Hydride (NiMH), alkaline (manganese dioxide, for example) and zinc-carbon batteries, while 26500 batteries are lithium batteries.
Nickel Cadmium (NiCd) rechargeable C cell batteries have nominal voltage of 1.2V, and they are able produce large currents, but their capacity and number of charging/discharging cycles is limited when compared with equivalent Nickel-Metal Hydride (NiMH) batteries.
Due to their relatively high discharge rate, memory effect, environmental impact of cadmium, NiCd batteries are being phased out, but still may be found in cheaper tools as C batteries or sub-C batteries (42.9 x 22.2 mm) with or without soldering tabs.
Nickel Metal Hydride (NiMH) rechargeable C cell batteries feature good capacity, they are cadmium/mercury free, have low self-discharge rate, tolerate large number of charging/discharging cycles, have good shelf life, etc.
Depending on the NiMH battery type, nominal capacity of NiMH C batteries vary usually between 4.0 and 6.0 Ah with nominal voltage of 1.2 volts.
Low drain NiMH C cell batteries feature larger capacity than high drain NiMH C size batteries, but high-drain models can easily produce 60-70 or even more Amps (model dependent!).
Note: Both NiCd and NiMH types of batteries should be charged only with the chargers designed for such battery chemistries. High-quality, well balanced and maintained NiMH batteries may withstand 700-800 charging/discharging cycles, more than justifying their initially higher prices.
Zinc-Carbon non-rechargeable C cell batteries feature nominal voltage of 1.5 volts and nominal capacity in the 3.0 - 4.0 Ah range. They are very affordable C size batteries intended for mostly low-drain applications. Also, they offer shelf life of 3-5 years
Alkaline non-rechargeable C cell batteries are most common C size battery chemistry. These batteries feature nominal voltage of 1.5 volts and nominal capacity in the 6.0 - 8.0 Ah range.
Alkaline batteries cost more than zinc-carbon batteries, but they have larger capacity and longer shelf life, sometimes 7-10 or even more years.
Alkaline batteries are intended for medium-drain applications including LED flashlights, portable radios, toys, and other similar devices.
Lithium non-rechargeable C size/26500 batteries are commonly Lithium Thionyl Chloride (Li-SOCl2) batteries featuring extremely low-self discharge rate (<1% per year), high capacity and are able to operate at low temperatures.
On the other hand, Lithium Thionyl Chloride (Li-SOCl2) batteries feature relatively high-internal resistance and are suitable for low-drain applications. Also, after being in standby for many years, they don't produce their nominal voltage right away - depending on the model, this time varies.
On average, Lithium Thionyl Chloride (Li-SOCl2) C cell/26500 batteries feature nominal voltage of 3.6 volts and capacity of 8.0 - 10.0 Ah - they are able to store 2.5 - 3x more energy than for example, alkaline C size batteries.
Rechargeable lithium 26500 batteries use several very similar lithium chemistries including IMR (LiMn204 - Lithium Manganese Oxide), INR (LiNiMnCoO2 - Lithium Manganese Nickel), IFR (LiFePO4 - Lithium Iron Phosphate), ICR (LiCoO2 - Lithium Cobalt Oxide) or some other similar/hybrid (LiNiCoO2 - Lithium Nickel Cobalt Oxide, LiNiCoAlO2 - Lithium Nickel Cobalt Aluminum Oxide, etc.) technology.
Their nominal voltage differs from 3.2 to 3.7 volts and nominal capacity from 3.0 to 6.0 Ah - again, some models are intended for low-drain and some for high-drain applications.
While both rechargeable and non-rechargeable lithium batteries are mutually replaceable, at least for low-drain applications, devices designed to be powered by C-cell batteries and nominal voltages of 1.2 - 1.5 volts should not be powered by lithium 26500 batteries due to the large voltage difference (more than 2x) - such voltage difference may damage the device.
Some newer devices including LED flashlights, toys, portable radios and similar are designed to be powered by either C-size batteries or 26500 batteries, despite the voltage difference - these devices feature small DC/DC converters ensuring that proper internal voltage is always available regardless of the input voltage.
Note: Only the devices that specifically state that they CAN be powered by either C-cell batteries or 26500 batteries should be powered by these batteries. Other devices should be powered by only one battery type as labeled by the device's manufacturer!
Long Story Short: If you have a device that is powered by C-cell or 26500 battery, check the battery type and get the battery of the same chemistry type.
Only if the device's manual clearly states that it may be powered by either C-size battery (nominal voltage 1.2 - 1.5 volts) or 26500 battery (nominal voltage 3.2-3.7 volts) consider replacing C-size battery with 26500 battery or vice versa.
Personally, if the device allows C batteries to be replaced by 26500 batteries, especially if the device is used often, do it - 26500 lithium rechargeable store more energy and may be recharged 1000+ times, depending on the battery model and type of use.
Note: always charge the batteries with the battery chargers intended for such batteries.