A few years ago I was asked about my preferred batteries for camera flash units – which to be honest, at the time I hadn’t really given much thought to, I just utilised whatever was on hand. But as time went on and my reliance on flash units increased, I began to notice an increasing number of under exposed or black images showing up in my collection of photos because one or all of my flashes hadn’t fired as required. It was at this point that I started experimenting with various battery types and discovered the obvious differences.
Before we begin discussing batteries, it is important that we understanding how a camera flash unit works. These devices momentarily simulate the sun by providing a huge blast of light – and just like the sun it requires a large mass of energy to produce that blast. To do this, the flash unit draws power from the small batteries (typically AA sized 1.5 volt units) and boosts it through the use of a capacitor. The capacitor takes the 1.5 volts and stockpiles it until it reaches several hundred volts. Once the flash is triggered, the capacitor rapidly discharges the power stored, producing the bright flash visible through the flash unit’s bulb.
Now if we are only using the flash unit on the rare occasion, then the battery source makes very little difference – but if we are constantly using the flash unit, then it is important that we utilise batteries that do not restrict the flow of power to the capacitor and allow it to rapidly recharge, otherwise the flash unit(s) will not fire when required, leaving us with under exposed and potentially black images. This is where quality batteries make all the difference.
So what really constitutes a quality battery? That isn’t a simple question to answer. There are numerous types of batteries, typically grouped by their chemical composition, and each has unique characteristics ranging from the amount of power they can supply, right through to how they react under extreme loads which are all useful in a variety of specific environments.
In this instance, we will be looking batteries (below) which meet the needs of flash photography, and rate each type with a rating out of five.
- Alkaline – 3 out of 5Alkaline batteries (e.g. Duracell Batteries) have low self-discharge and can be stored for a long time. They will also last for a long periods when used to power low-current devices – which camera flashes are not, and tend to drop their voltage under load.
These batteries are not rechargeable and will need to be disposed of once their power is depleted. Additionally, heavy use of these batteries in a camera flash units can cause them to become excessively hot, and can potentially cause burns (though it should be noted that they not as hot as Lithium batteries).
- Nickel Oxyhydroxide – 4 out of 5Designed as a substitute for alkaline batteries, they are designed to last longer in high drain electrical products such as flashes, and produce a higher voltage of 1.7 volts compared to an alkaline that only typically produces 1.5 volts. Whilst this may sound like a great thing, it should be noted that in devices without voltage regulators, these batteries may potentially cause damage to electrical circuits.
These batteries are not rechargeable and will need to be disposed of once their power is depleted.
- Lithium – 2 out of 5Lithium batteries (e.g. Energizer Lithium Batteries) have a low self-discharge rate, and unlike other batteries such Alkalines, can carry a large amount of power. This kind of chemical composition can be found in other battery sizes including AA, AAA and button type batteries (e.g. CR2032).
The voltage in these batteries can range from 1 to above 3 volts, and if utilised in the place of a 1.5 volt battery can cause major damage to electrical circuits because when made to rapidly discharge can result in overheating, and furthermore have been known to even explode in rare circumstances. Though modern lithium batteries now come with built in thermal protection to prevent such accidents from happening, they can still become excessively hot – so much so that they can result in burns if they come in contact with human skin after excessive use, or even melt camera flash cases. This is one of the reasons many electrical manufactures warn against use of such batteries in their devices – and generally for good reason.
It is not recommended that these batteries be utilised in flashes unless specifically advised by the flash unit’s manufacturer. They are also not rechargeable so will need to be disposed of once their power is depleted.
It should also be noted that if you do decide to use these types of batteries and are utilising them heavily, the camera flash may temporarily stop working if the battery’s thermal protection circuit kicks in (that is if they have thermal protection), and you will not be able to use the flash until such time as the thermal unit decides the batteries have cooled down enough to work again – which obviously is not something you want to happen to you on a live shoot like a wedding.
- Nickel Cadmium (NiCd) – 1 out of 5NiCd batteries are the cheapest kind of rechargeable battery, and produce only about 1.2 volts.
They are one of the oldest rechargeable batteries, and suffer from issues such as ‘memory’, whereby if the battery is not charged and then depleted completely, they begin to malfunction and quickly stop working. Additionally, these batteries are prone to being over charged and contain poisonous materials.
Though still available, these batteries are dinosaurs by comparison to newer rechargeable batteries and it is advisable to avoid them.
- Nickel-Metal Hydride (NiMH) – 5 out of 5NiMH batteries (e.g. Duracell or Eneloop Rechargeable Batteries) are a newer type of rechargeable battery, and produce about 1.2 volts. They have low internal resistance and are capable of powering electronics that drain power quickly such as camera flash units.
Like NiCd batteries, NiMH batteries do not deal well with overcharging, do not hold their charge very well (therefore it is advisable that you recharge you batteries on the day or the night prior to your shoot), cannot be stored for lengthy periods with no charge (so be sure to fully charge them every 5 to 8 weeks even if they have not been utilised) and should not be ‘fast charged’ as they can potentially suffer ‘memory’ issues.
In summary, the best batteries to use are those that are marked as ‘NiMH rechargeable’ (e.g. the Duracell or Eneloop Rechargeables) with a mAh rating of 2800 or higher. These batteries will provide a consistent level of power as required by camera flash units, reduce the level of poisonous chemicals and metals commonly produced by an abundance of discarded disposable batteries; and will keep producing consistent power right until they are completely depleted.
My own personal preference are Japanese manufactured ‘Duracell Rechargeable’ batteries as they have proven to be reliable, cost effective and available almost everywhere. I have also recently started using a combination of Duracell and the more expensive Eneloop Pros produced by Panasonic also in Japan. These Eneloops Pros are double the price of Duracells, but are meant to hold their power for longer periods when not in use. But in relation to providing more of less power, I have noticed no significant difference between the two batteries with identical mAh ratings.
In case you are wondering, the capacity of a battery is listed as ‘mAh’ (e.g. 1200 mAh, 1800 mAh, 2500mAh etc.). This number indicates how long a battery can continue to provide a specific current. The higher the mAh rating, the higher the battery’s capacity to provide ongoing power. Therefore a battery with 2500 mAh is a much better choice than a 1200mAH battery.