When buying rechargeable batteries there are 3 things that determine the quality of the product:
- The amount of power a battery can store,
- For how long the battery can store that power,
- The number of recharge cycles the battery can do before no longer holding a charge.
Looking at the first 2 qualities in terms of a bucket of water, point 1 would be how much water the bucket could hold, and point 2 would be the size of the hole in the bucket.
Interestingly, though, a better brand doesn't equal a better battery, and for most consumers it isn't possible to find out which batteries are better without buying a lot of different brands and trying them side-by-side. Conducting this experiment can cost hundreds of dollars, and for most people, the length of time a battery holds its charge is the most crucial factor. Some brands hold a huge amount of power but, left sitting on the shelf, will discharge within 7 days. AND, surprisingly, a greater milli amp rating doesn't guarantee slow discharge either.
The most popular brands of Nickle Metal Hydride (NiMH) batteries sold in Australia are ranked below in order of most power retention and recharge cycles to least, when used in either high drain or low drain devices:
- Dick Smith / PowerHaus / DSE / Digitor (same battery, same retailer, different names)
- Sanyo Eneloop
- Energizer (quite poor)
- Sanyo (appalling)
I have had 4 sets of Sanyo NiMH batteries and they have all been a waste of money, despite being the pioneers of higher capacity, and discharge (unused) within 7 days. Our company has also used quite a lot of Energizer NiMH batteries and they typically discharge within 10 days. Duracell & Digitor will last for 8+ months in low drain devices such as clocks, air-fresheners, computer keyboards and remote controls and they work wonders in high drain devices like digital cameras and MP3 players too. And the great news is Digitor batteries are very well priced and can charge very well in a wide variety of chargers. (Note that Digitor also has higher mAh rating batteries as well).
Sanyo has also just released a new line called Eneloop. They are a high capacity battery being already charged in the packet ready to go, and they hold 90% of their charge and recharge after 12 months in storage. Their AA version is 2000 mAh, which isn't fantastic by comparison to Duracell, but might just do the trick in devices not used very often such as torches.
The moral of the story is simple, shop around and test your brands before buying a cupboard full of one brand, because when it comes to NiMH batteries, brand is no guarantee of quality.
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