Batteries come in all shapes and sizes and work on different principles of chemistry. The common batteries used in cameras and speedlights are AA in size though the smaller version called AAA is also becoming quite popular. I will restrict my discussion on these batteries since this is where we are faced with choices. The odd shaped batteries that come in DSLRs and some other cameras are made as per camera specifications and we really don’t have much choice there. I do not recommend using cheap third party batteries after having invested a huge amount in your camera.
Big question faced by photographers is whether to use the usual non-rechargeable or rechargeable batteries. For high-drain devices like cameras, battery grips and speedlights it definitely is better to get decent rechargeable batteries. It is more environment friendly too. The initial cost is recovered when these batteries are reused again and again. Some companies now even sell batteries that have been initially charged using solar energy.
Chemical reactions that generate power differ in some of the common varieties of batteries. Common types of these AA/AAA batteries –
Carbon Zinc/Zinc Chloride
These are the ones that are commonly found everywhere and are the least expensive battery type. The backup provided by these is very less and so for high-drain devices these are not at all recommended. Use them only for the pen-light in your camera bag if you also carry one like I do.
These are the least commonly available of the non-rechargeable batteries and are the best option in this category. The number of flashes than can be had from your speedlight while using these are probably the highest. They also have a very long shelf life. Use these for standby.
Duracell and Energizer batteries became famous for their Alkaline offerings. Remember the bunny advertisement where it keeps going on and on? They have a higher capacity than the common Carbon-Zinc/Zinc Chloride batteries. Alkaline batteries are useful if you use your flashlight once or twice a year and also as a last resort in a camera or speedlights.
Nickel-Metal Hydride (NiMH)
If you are looking to go down the AA rechargeable route, then NiMH batteries are the best choice. By going for rechargeables, you are doing your pocket and environment a favor. These are safe and can be charged multiple times. There are new versions available that can hold the charge to really long duration too. Only trouble is that if they are kept in their discharged state for long, the batteries may refuse to charge again. The new charge retaining NiMH batteries are my personal choice for all my speedlights. I charge them as soon as they are drained. (I use various versions of Eneloops and Camelion batteries)
These were the first rechargeable batteries that became commonly available. These are pretty much obsolete these days. The cadmium used in these batteries is also harmful to the nature as well as humans. The advantage with these batteries is that these can be stored as long as one wants to. Recharge them and they are ready to work. These do not refuse to charge as NiMH batteries can. Their capacity is not as high as NiMH and so do not depend on them for high drain devices.
Choosing the correct batteries –
Use rechargeable batteries if your camera/speedlight usage is anything more than once a month. This is purely from the return on investment perspective.
Alkaline or Lithium (not to be confused with Li-ion) batteries can be used as standby or as a last resort. These also make sense from the financial perspective if your use is going to be once or twice in a year.
Forget about all the other types I have listed above.
Some basic number crunching-
The batteries have a mAH rating. This is a rating of energy storage capacity. (mAh = milli-ampere hour). Batteries with 2000 mAh rating, will have twice the capacity of a 1000 mAh rating. Higher capacity batteries provide more juice per charge but the number of times these can be recharged is less than low capacity batteries. The mAH rating has no effect on compatibility of batteries across devices. The rechargeable batteries are quite frequently marked as 1.2 volts where as the non-rechargeable batteries are 1.5 volts. All the devices that use these batteries work well with 1.2 volts. In fact, the voltage of non-rechargeable batteries also dips to 1.2 volt for most of their lifetime. They give out 1.5 volts only initially.
Choose a good charger
Apart from choosing the correct batteries, choosing a correct charger is also important. Proper charging can prolong the life of rechargeable batteries, whereas improper charging can spoil the batteries. There are four main types of chargers that are available for NiMH batteries in the market.
There are these super cheap chargers which are quite frequently available at dollar stores. These send a constant current to the batteries and do not have a cut-off when the batteries get charged. This is damaging. Keep away from these chargers.
Then there are the inexpensive chargers that come with batteries. These charge the batteries in pairs. A single battery can not be charged in these chargers. Some of them vary the current with the charge-level of the battery pair but there is no cut-off provided. Sometimes there is a cut-off provided which kicks in when all the pairs have charged. The fact that the batteries are charged in pairs is once again not a good thing. Different batteries (even if from the same manufacturer and with same level of drain) have different charging times. Charging them in pair tends to spoil the quicker ones and under-charges the slower ones. Avoid these chargers too.
I prefer the chargers that have individual charging circuits for each battery. These are also called as smart chargers. They even have a microprocessor controlling the charging. Each battery is charged individually, the current varied as per the charge level and then cut off when charged. This ensures proper charging and so better life. Some of these smart chargers also have a refresh function to completely drain the batteries and then recharge them again.
The newest kids on the block are the fast chargers. Some of these are capable of charging batteries in less than half an hour. Good for emergencies but not something that I recommend. The batteries tend to get hot when charged so quickly. In fact, some of these fast chargers have built in fans to keep the batteries cool. Such fast charging is detrimental to batteries. Do not use them regularly.
Best practices for rechargeable batteries –
- Store them charged. Storage for a long time is best avoided and still if you have to do so, remember to charge them completely once the charge level reaches around 10%.
- Use smart chargers.
- Charge the batteries in a cool place.
- Follow the instructions on the batteries.
- Do not mix and match battery brands and types. Do not mix old and new batteries. Do not mix batteries of differing charge levels.
- When using them in flash and when the flash is intended to be used more than 20-30 times in a matter of minutes, shift to external battery packs or give them time to cool down.
- Do not drop the batteries.
- Avoid exposing them to extremes of temperature.
- Feel free to charge them as and when required. The new NiMH batteries have minimal memory effect.
- Refresh the batteries once in every six months. If your charger does not have a refresh function, discharge the batteries completely and charge them fully. Any more frequent that this is counter-productive and will expose the batteries to undue stress.
Keep an eye on chargers –
- Do not use chargers where single batteries can not be charged.
- If you happen to have NiCd chargers, do not charge NiMH batteries on them.
- The batteries feel warm when they are charging but they should cool down when the trickle charging kicks in. If they don’t then the charger is providing more than the required amount of charge during this phase.
- Do not use very slow chargers or extremely fast chargers.
- Remove the batteries from the charger once they are charged. Don’t use the charger as a storage device.