Even though rechargeable batteries work under a wide temperature range it doesn’t mean you can charge them at the same temperatures. You may not be able to control the temperature while operating batteries, but you can control it while charging them and you should try to use a battery charger to charge batteries at moderate temperatures.
You can charge Lithium-ion batteries between 32°F and 113°F; however, it’s recommended to lower the charge rate to less than 1°Cwhen charging between temperatures of 32°F to 41°F. Consumer grade lithium-ion batteries can’t be charged below 32°F as the cell impedance rises and the acceptance of the ions on the anode is greatly reduced. Plating of metallic lithium often takes place on the anode and it gets worse at a higher charge rate. Prolonged charging at cold temperatures could result in an unsafe battery. A good battery charger won’t charge the battery below 32°F; however, special military and aerospace Lithium-ion batteries can be charged at low temperatures.
In general, older battery types such as nickel cadmium are more tolerant to temperature extremes when charging. These batteries can often be fast charged in about an hour; however, the charge should only be done between temperatures of 41°F and 113°F. Moderate temperatures of 50°F to 77°F will generally produce better results, though.
Charging these batteries below 41°F requires a reduced charge rate of 0.1C, which is 10 percent tenth of the rated current. The oxygen and hydrogen can be absorbed within the cell at this rate and a fast charge would result in excessive cell pressure and cell venting. Under these conditions, a battery wouldn’t be able to receive a full charge.
Nickel-metal-hydride (NiMH) batteries can’t be fast charged below 45°F, or slow charged below 32°F. Some types of industrial battery chargers are made to adjust the charging rate to the existing temperature. The charging ability of nickel-based batteries is greatly reduced if charged at a higher temperature. A battery that receives a full charge at moderate room temperature can only receive 70 percent capacity if it’s charged at 113°F, and can only be charged to 45 percent at 140°F. This is why some types of chargers don’t work too well in the summer.
You can usually charge lead-acid batteries, such as car batteries, in freezing temperatures and with low-level charging. To get better results and longer lasting batteries, when you’re charging them in cold temperatures it’s important to control the voltage limits to which the battery is charged.
In most cases, heat will eventually destroy a battery as the warmer the cells are, the shorter the battery’s life will be. If you have to charge a battery in high temperatures, try to keep it short and remember that the cells inside the battery are always a few degrees warmer than the battery housing.