Lithium 18350 Battery Equivalents and Replacements
Lithium 18350 battery is a rechargeable 3.6-3.7V battery commonly used in high-drain devices including flashlights, cameras and other photo equipment, medical and security systems, etc.
18350 battery feature physical dimensions that are very similar to several other battery sizes, making it "almost" compatible with such batteries. But, such "almost" compatibility may lead to confusion among its users.
Published: October 8, 2021.
18350 Battery Features and Specifications
The physical dimensions of the 18350 battery are (D x H) 18 x 35 mm (0.708 x 1.378 inches) with the nominal voltage of 3.6-3.7 volts and capacity between 600 and 1400 mAh, standard discharge current between 2 and 10+ Amps and maximum burst current of 15 or even more Amps.
Nominal voltage, actual capacity, and drain currents depend on the exact 18350 battery chemistry:
- IMR 18350 lithium batteries feature LiMn204 (Lithium Manganese Oxide) chemistry, a nominal voltage of 3.6 - 3.7 V per cell, and a maximum recommended charging voltage of 4.2 V. IMR 18350 batteries on average have a smaller capacity but are capable of delivering very strong currents.
- INR 18350 lithium batteries feature LiNiMnCoO2 (Lithium Manganese Nickel Cobalt Oxide) chemistry and are very similar to IMR batteries. INR 18350 batteries can provide strong currents, with slightly lower capacity.
- IFR 18350 lithium batteries feature LiFePO4 (Lithium Iron Phosphate) chemistry, a nominal voltage of ~3.2 V per cell, and a maximum recommended charging voltage of 3.5 - 3.6 V. Lithium 18350 batteries are the safest lithium 18350 batteries, but even they require the built-in BMS to operate safely.
- ICR 18350 lithium batteries feature LiCoO2 (Lithium Cobalt Oxide) chemistry, a nominal voltage of 3.6 - 3.7 V per cell, and the maximum recommended charging voltage of 4.2 V. Lithium ICR 18350 batteries commonly have higher capacities, but maximum allowed currents are often limited to just a few C.
Note: there are other chemistries on the market too, but they are not often used in 18350 batteries.
High-drain 18350 batteries are commonly either IMR 18350 or INR 18350 batteries.
As rechargeable batteries, 18350 batteries may withstand hundreds of charging and discharging cycles, depending on the storage/drain temperature, charging/discharging current, battery quality in general, the quality of the 18350 battery charger, and similar.
Note: Just like any simile lithium battery, 18350 batteries should be recharged only using battery chargers intended for 18350 lithium batteries.
Some 18350 batteries are "protected 18350 batteries" - they contain Battery Management System (BMS) on a small PCB within the battery itself.
Such BMS protects the battery from unwanted events like high/low voltage, high/low temperature, short circuit, overcurrent, and similar.
Also, such BMS occupies some volume of the battery, decreasing the capacity.
But, in order to prevent the capacity loss, some manufacturers offer protected 18350 batteries but somewhat longer due to the BMS, keeping the original capacity.
This is great, if the device can accept such "longer" but "protected" 18350 batteries, since such batteries may be 2-4 mm longer than the standard 18350 battery.
18350 Battery vs Other Similar Batteries
Physical dimensions of the 18350 and few similar batteries are:
- 3.7V 18350 battery (D x H) 18 x 35 mm,
- 3.7V RCR123A battery (D x H) 17 x 34.5 mm: RCR123A is a rechargeable CR123A battery, often labeled as a 17345 battery. Both RCR123A (17345) and 18350 batteries feature very similar dimensions, except that the 18350 battery is slightly wider, with the height being almost the same.
If the device intended for the RCR123A (17345) battery features a battery compartment wide enough, it can accept both RCR123A (17345) and 18350 batteries.
- 3.7V 18650 battery (D x H) 18 x 65 mm: 18650 battery is almost twice as long as 18350 battery. Since some devices feature battery compartments intended for either one 18650 battery, or one protected 18650 battery (which may be few millimeters longer than standard 18650 battery) or two CR123A (or RCR123A, or 17345) batteries, such devices often can accept two 18350 battery.
However, just in case, before switching from one 18650 battery to two 18350 batteries, check the Owner's Guide of the device that You have if such switch is explicitly permitted by the manufacturer of the device.
- 3.7V 18700 battery (D x H) 18 x 70 mm: 18700 battery features exact dimensions of two 18350 batteries stacked on one another. Also, some protected 18650 batteries feature a height closer to 70 mm than 65 mm.
Thus, if the device is powered by 3.7V 18700 battery and it is allowed by the device manufacturer to replace one 18700 battery with two 18350 batteries, feel free to do so.
Just be sure that the new pair of batteries is able to provide strong enough current.
- 6V CR-P2 battery (H x L x W) 36 x 35 x 19.5 mm: CR-P2 is a flat lithium battery internally consisting of two CR123A batteries and in many devices, it can be replaced by a pair of 3.0V CR123A batteries.
If the device supports the use of pair of 3.7V batteries then one can use a pair of RCR123A (17345) or a pair of 18350 batteries instead of one CR-P2 battery.
Note: due to the width differences, a single CR-P2 battery fits the battery compartment better than the pair of 18350 batteries and much better than the pair of CR123A/RCR123A (17345) batteries. Not to mention that the CR-P2 is designed in a such way that it can't fit the battery compartment the wrong way ...
- 6V 2CR5 battery (H x L x W) 45 x 34 x 17 mm: 2CR5 battery is in many ways similar to CR-P2 battery, but it is somewhat higher but narrower. Many devices come with a battery holder that can accept two CR123A batteries (or RCT123A/17345, if the higher voltage is allowed), but may have issues with a somewhat wider 18350 battery.
Again, if You plan to replace the 2CR5 battery with a compatible battery holder that accepts two RCR123A/17345 batteries, such battery holder may accept two 18350 batteries.
But, with two 18350 batteries, it may NOT fit the battery compartment of the device in question.
So, if You plan to replace the 2CR5 battery with a pair of 18350 batteries, check the Owner's Guide of the device and see if 18350 batteries are compatible with your device.
Long Story Short: Lithium 18350 batteries feature relatively good capacity and are generally capable of providing really strong currents. Thus, they are often used in high-drain devices.
When looking for a new 18350 battery, check the batteries from reputable brands that have good reviews from many users - just be sure that they are able to provide strong enough currents.
Again, 18350 batteries and other similar lithium batteries should be always recharged using lithium battery chargers intended for such batteries. Better safe than sorry ...