Switching to Rechargeable Batteries

Many everyday devices such as alarm clocks, remote controls, torch lights and even some digital cameras rely on the humble dry cell.

Dry cells come in various common sizes such as AAA, AA, C and D. The most common batteries make use of chemistries such as Carbon-Zinc, otherwise known as General Purpose or Heavy Duty , or Alkaline, perhaps the most commonly found battery nowadays. Devices which tend to experience higher power drain such as Digital Cameras tend to be outfitted with disposable Lithium batteries, which are lighter, but also have a higher energy density.

Environmentalism

Batteries are extremely environmentally unfriendly. Older batteries sometimes have chemistries including toxic heavy metals such as lead, mercury and cadmium. Upon disposal, many of these batteries end up in landfills, where they corrode and leech these chemicals into the surrounding environment. Heavy metals can stay in the environment for long periods of time, and there is always the risk of them migrating up the food chain. Even newer batteries can corrode, and even though the chemicals they release are not as toxic, they are still extremely harmful to wildlife, and linger in the environment long after the battery was disposed.

While the environmental impact of batteries in terms of toxicity has been extensively documented, one often overlooked aspect of their impact is the wastage of finite resources. The metals and chemicals used in batteries are packaged so tightly that they are not easily reclaimed by current recycling processes. Additionally, metals and metal salts such as Lithium are comparatively rare, with natural concentrations at around 20mg per kg of crust, and using the metal in disposable batteries will deny its usage in other processes.

Cost

In high drain applications such as Digital Cameras, it is often cheaper to buy and maintain a set of rechargeable batteries. With rechargeable batteries, there is always the hassle of having to recharge them as they become depleted. However, modern batteries are designed to charge quickly, and it is now possible to obtain a full charge using regular chargers in as little as 1 hour. Special fast chargers are able to deliver a full charge in as little as 15 minutes, but will damage your battery over time.

While still not as long lasting as Lithium batteries, the lower capacity of rechargeables can be mitigated by maintaining two or more sets. Though the initial cost of purchase may be considerably higher than contemporary disposable dry cells, the difference is quickly recovered.

One of the main counter-arguments often used against rechargeable batteries is their inability to retain charge. While this might be true of older generation batteries, newer batteries such as those marketed under Sanyo's Eneloop, are able to retain most of their charge, even over extended periods of time. This means that a set of rechargeable batteries last charged a month ago will still be able to power your equipment today, making them a viable alternative to disposable cells in uses such as cameras and flash guns.

Corrosion

Normal batteries corrode. When they corrode, they release chemicals which are not only bad for the environment, but are also caustic and corrosive. There are many people who can share with you experiences where perfectly good and long lasting devices have been destroyed by battery corrosion: corroded batteries leak a sticky and caustic liquid which seeps out of the battery compartment, soaking the sensitive electronics within in a corrosive fluid. 

The damage does not stop even after the offending batteries are removed: Often, the only way to preserve devices which have been damaged by corroding batteries is to open them up and fully wipe down any surface that may have come into contact battery fluid. 

Battery Charger

Obviously, the key component in any rechargeable battery system is the charger. There are many types of chargers which offer varying charge times and running on different energy sources. More common chargers plug into your wall socket and deliver a full charge in 2-3 hours. Specialist chargers may provide a trickle-charge, drawing their energy from solar power, or charge batteries in as little as 15 minutes, by forcing huge amounts of current through the cell.

Standard chargers are well suited for regular usage, as they deliver full charges relatively quickly. While abroad, or in situations which usually have a high turn-over rate for batteries (such as concert photography with a flash gun), the 15 min quick chargers might be a better choice. However, it should be noted that force-charging rechargeable batteries drastically reduce their lifespan, and should not be done on a regular basis.

Solar chargers, at the time of writing, are not yet viable, offering at best a trickle charge under the brightest of lights.

The Batteries

The most common rechargeable battery chemistry at the moment is Ni-MH, or Nickel Metal Hydride. The amount of energy, or charge, a typical Ni-MH battery can store ranges from 2200-2700mAh. When buying rechargeable batteries, it is important to differentiate from conventional rechargeables, which will gradually lose their charge over a period of a few weeks, from rechargeables with special and often proprietary additives and technologies that allow them to retain their charge for months on end.

Some manufactures such as Sanyo sell these rechargeables fully charged, and they can be a great alternative to disposable cells when you run out of power on the go, as you may recharge them even after the moment of need passes.

Compatible Devices

Almost all devices are compatible with rechargeable batteries. However, there exist a handful of devices which will simply not run on Ni-MH rechargeable batteries. This is because while disposable Heavy Duty and Alkaline cells have a nominal voltage of 1.5v, most rechargeables can deliver a maximum of 1.2v.

Fortunately, an emerging chemistry known as Nickel-Zinc aims to solve this problem, by providing high capacity 1.5v rechargeable batteries which are capable of retaining their charge.