Used Camera Charger Buying Guide

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Used Camera Charger Buying Guide

Very few digital cameras have a USB charging facility as it is a very slow way to regenerate the power source. On the other hand, many cameras – digital and otherwise – have battery power sources and these will be available as either single use items or as rechargeable units. Furthermore, each type of battery will have pros and cons that will lead them to being used in specific circumstances.

Types of Batteries

Many digital cameras use standard AA batteries, but these are available in a range of styles:
 

Type

Description

Alkaline batteries

An alkaline battery delivers a steady capacity, but it is limited when providing for a heavy load – such as digital camera. Although rechargeable alkaline batteries are available, single use units are much more commonly produced. Any attempt to recharge a single-use battery may cause leakage or the rupture of the unit which will – in turn – damage the equipment it is supposed to be charging. These types of batteries will have a relatively short lifespan in a digital camera.

Nickel Cadmium (NiCd)

NiCd batteries were the first popular rechargeable battery to be used by general households. Available in all of the standard battery sizes, they are particularly robust. They perform well in both heat and cold and are resistant to overcharging. The Cadmium used in their construction, however, is very toxic and they have a memory effect which reduces performance if they are not fully discharged before recharging. There is also now a legal requirement that they must be properly disposed of after use.

Lithium-ion (Li-Ion)

Many manufacturers recommend Li-Ion batteries which are light, are rapidly charged and discharged and can endure cold weather temperatures. They are less impacted by any memory effect if recharged before full discharging and have a high charge retention, capable of being recharged over a thousand times before needing replacement. Lithium batteries are often matched to a device, limiting their use slightly. Yet their advantages do mean that they are generally the standard for most digital cameras.

Nickel Metal-hydride (NiMH)

Heavy and slow to charge, NiMH batteries are nevertheless more durable and have a longer working life than Li-Ion batteries. Their power and several technical environmental and technical advantages have seen them replace NiCd batteries as the preferred rechargeable power source for most appliances. They also do not suffer from the memory effect that hampered the use of NiCd batteries, although it is advisable to let them fully discharge before recharging in order to achieve a maximum life span.

Types of Battery Charger

Battery chargers are available as mains-powered, car-powered or solar and are generally divided into three categories - dumb chargers, smart chargers, and battery managers:

Type

Description

Dumb Chargers

Dumb chargers are also called overnight or slow chargers. They contain no sensors or level measures, so simply charge a battery for a set amount of time – usually 12 to 16 hours – before stopping. Overcharging can severely reduce the life span and capability of a battery. A dumb charger is often included as part of any rechargeable battery bundle and the timer inherent to the device is non-adjustable.

Smart Chargers

Many smart chargers contain a computer chip to control the charge. This type of charger will assess the charge level of a battery and will either stop charging or switch to trickle charger mode when the power level is at a certain point. These chargers also have higher charging currents and so have the capability of fully charging a battery within 2 to 6 hours.

Battery Managers

A battery manager is a smart charger with additional functions. As well as charging the battery, it can also discharge (in order to fully maximise life span), condition and analyse the capacity of a battery. A sophisticated battery manager often comes equipped with LCD displays to properly show the state of the battery. That is to say, it will display in real time the capacity and voltage so that a determination can be made about use and suitability for a device or task.

There are also Super-Fast battery chargers available. Using a very high current, these smart chargers can recharge a battery in less than 30 minutes, but they do cause increased heat which will deteriorate a battery considerably. It is recommended that a user only employ a Super-Fast charger very rarely if battery capability is paramount, although their speed can be beneficial in certain circumstances, for example, news photography.

It is important to note that, although some NiMH battery chargers can handle NiCd batteries, the reverse is not true.

How Battery Status is Determined and Controlled

To determine the state of a battery, a smart charger can use one or all of these techniques to calculate and control the level of charge present:

Technique

Description

Trickle Charging

Many chargers support trickle charging capabilities. This means that when the charger detects that a battery is fully charged it will automatically switch to trickle charge mode. As this is generally a 5 per cent charge rate in comparison to the usual rate, it ensures that the charge is gently maintained at full capacity until the battery is disconnected.

Negative Delta Voltage Detection (−ΔV)

As a NiMH battery is charged the voltage increases constantly, but when the battery is almost fully charged, it will show a voltage drop. A charger that uses this drop to determine battery status is using negative delta voltage detection (−ΔV).

Temperature Monitoring

When a battery is fully charged but the charge continues, they will release the charge that cannot be contained by converting the power to heat. By monitoring the battery temperature, a smart charger will be able to suspend charge until the heat has been released. Although negative delta voltage (−ΔV) is usually the primary detection method, temperature monitoring is often used as a secondary source of condition determination.

Voltage Monitoring

A NiMH has specific voltage levels that will determine the charge contained. By continuously monitoring the voltage of a battery, a charger is therefore able to detect precisely when to switch to trickle charge mode. This method is known as Delta V and some chargers use both Delta V and -ΔV to determine the state of a battery.

Considering a Used Charger

When purchasing a used battery charger, it is important that all components are in good order to ensure safe use. Therefore, before use, it is vital to check that all power leads are intact with no cracks, splits or damage; that any plug is properly fastened and that the casing is not cracked or showing visible deterioration and that all connectors within the battery compartment are secure and functional.

Conclusion

Digital cameras rarely have a USB charging facility as it is a very inefficient method of renewing the power capability. Instead, they generally come with battery sources that can be purchased as either single-use or rechargeable units. Alkaline batteries are not often available as rechargeable sources, but nickel metal-hydride (NiMH) and lithium-ion (Li-Ion) are. Rechargeable batteries do need a charger, and buying a used battery charger is an worthwhile option. When considering a used charger it is vital to ascertain that all components are secure, undamaged, functional and in good working order.

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