Gone are the good old days when cameras depended on two button cells or two AA batteries for power. Gone also are the films and winding levers of the manual age. With the advent of digital photography, cameras have changed from those simple light-tight boxes with a shutter to the power-hungry, sophisticated equipment that we know them to be today. Cameras need power for everything—right from displaying images to zooming in and out. And because of the lack of standardisation in the batteries, these power sources range from common AA sized ones to bulky, specialised battery packs for professionals. These tips will help you choose and maintain your batteries.

These are proprietary rechargeable batteries that you get with most cameras. Lithium-ion (Li-ion) batteries have higher open circuit voltage than other competing batteries like lead acid, nickel metal hydride and nickel cadmium. Another very important consideration is that these batteries do not suffer from the memory effect. They also have a low self-discharge rate, compared to other batteries.

Contrary to common belief, a Li-ion cell must never be discharged below a certain voltage. Therefore most Li-ion battery systems have a circuit that shuts down automatically when the battery is discharged below a certain limit. If you intend to store the batteries unused for a long time in the camera, it should not be fully discharged, or it can damage the batteries. Ideally, they should be stored with about 40 percent of charge. Though Lithium-ion batteries should not be frequently fully discharged, this becomes necessary after about every 30th recharge for optimum results. This prevents the fuel gauge from showing an incorrect battery charge. Li-ion batteries should be stored in a refrigerator if you intend to store it for long, but do not freeze the batteries.

These batteries are fast getting replaced by Nickel Metal Hydride (NiMH) batteries mainly due to the toxic effects of Cadmium. For charging Nickel Cadmium (NiCd) batteries, you need to use a charger with good charge capacity, fast chargers being more efficient. But faster charging has a higher risk of overcharging, which can damage the battery. Most battery chargers for NiCd batteries are equipped with automatic cut-off circuits. The safe temperature range for a NiCd battery in use is between −20°C and 45°C. As the battery nears full charge, the temperature will rise to 45–50°C. Some battery chargers are capable of detecting this temperature increase and cut off charging at this point. NiCd battery has a high self-discharge rate. To retain the full charge, many battery chargers are capable of giving a ‘trickle charge’. If you need to store the battery unused for a long time, it should be discharged to at most 40 percent of its capacity.

It is best to let the battery cool before recharging because a warm battery will not get charged to its full capacity. If there is a slight difference in the capacity of cells, one of the cells will usually be fully discharged before the others; this results in reverse charging, which can reduce battery life. So it is always better not to mix batteries of different capacities or even different batches of batteries. There are battery chargers that can discharge all the cells before charging so that the voltages remain equal.

NiCd batteries often suffer from ‘memory effect’ when recharged before they have been fully discharged. This prevents the batteries to get fully discharged after a few charge-discharge cycles, and thus the full capacity of the battery is not fully utilised. Another similar phenomenon is lazy battery effect. This results from frequent overcharging. In both the cases, the battery appears to be fully charged but discharges very fast. Sometimes, this lost capacity can be recovered by a few deep discharge cycles. Some battery chargers have this feature built into them. NiCd batteries contain cadmium, which is a toxic metal that can cause severe environmental pollution.