Editor, AndersonlawBlog
Rechargeable batteries used to suffer from two fatal flaws: First, the old NiCd batteries ran out too quickly, making alkaline batteries an easier choice because they lasted longer. Second, rechargeable batteries have a tendency to self-discharge, which means that they lose a certain percentage of their stored energy every day, even when you aren't using them. This made using rechargable batteries in seldom-used or low power products, like remote controls, impossible. It appears that modern technology has solved both problems.
Today, you can buy NiMH (Nickel Metal-Hydride) batteries in AA, AAA, C, D, and 9-volt versions that store as much energy as ordinary alkaline batteries. In high drain devices like cameras, NiMH batteries actually last longer than disposable alkaline batteries. More importantly, you can buy chargers that will charge AA/AAA NiMH batteries in 30 minutes or less. And some (but not all) of these batteries have solved the self-discharge problem, and can retain their charge for a year or longer. As a result, you can now put a rechargeable battery in your remote controls and other devices that you don't use very often, and the battery will still be running a year or more from now.
Here is everything you need to know about replacing your standard alkaline batteries with NiMH rechargeables.
1. There are dozens of chargers for rechargeable batteries. Produc
ts from Sony, Energizer, and Duracell are the most popular and are readily available. Unfortunately, most are poorly marketed and lack flexibility in how you use them.
ts from Sony, Energizer, and Duracell are the most popular and are readily available. Unfortunately, most are poorly marketed and lack flexibility in how you use them.
The best AAA/AA NiMH charger is the model BC-900 from Lacrosse Technologies, which you can buy at amazon.com or from thomasdistributing.com. This charger can charge between 1 and 4 batteries at a time, and you can pick the charging speed that suits your needs. If necessary, you can charge a battery in under an hour. If you're not in a hurry, you can also slow charge a battery in under 11 hours. Why the difference? It is believed that faster charging shortens the total lifespan of the battery.
This charger is also full of useful features, like a discharge/recharge and a condition cycle (you can reach more about these features in the user manual). It also has a full LCD screen which will show you battery voltage, mAH (milli-Amp Hours), and duration of the charge.
2. If you want to use a AA/AAA rechargeable NiMH in a remote 
control or another setting where you need the battery to have a very low-discharge rate, look for batteries that are specifically marketed as "low-discharge". Sometimes they are also advertised as "pre-charged." These batteries can maintain 85% of their charge after a year of sitting around.
control or another setting where you need the battery to have a very low-discharge rate, look for batteries that are specifically marketed as "low-discharge". Sometimes they are also advertised as "pre-charged." These batteries can maintain 85% of their charge after a year of sitting around.
The most common brands that fit in this category are Sanyo's Eneloop, Ansman Max-E, Acupower Acculoop, the Uniross Hybrio, and the Ray-O-Vac Hybrid. You can buy many of these products at amazon.com and at thomasdistributing.com. As I write this, there are no "low discharge" C and D cells batteries available, but you can buy sleeves that let you use a AA battery in a C or D cell application. Understand that run times will be much shorter, though. You can buy them at http://www.thomasdistributing.com/. A nice bonus is that the Eneloop batteries come with a handy plastic carrying case.
3. When shopping for traditional NiMH batteries (the ones that are not low-discharge), pay special attention to the mAH rating, which is essentially the fuel level of the battery. AAA's should be between 800 and 900 mAH. AA's should be around 2,500 mAH. C-cells should be about 5,500 mAH and D-cells should be around 11,000 mAH.
4. Beware of the cheapo Energizer C and D NiMH cells. They are really AA's in bigger cases. Instead of having 5,500 and 11,000 mAH, they really only have 2,500 mAH. If you need C or D cells, look for cells made by Maha PowerEx or Accupower. You can buy both at http://www.thomasdistributing.com/.
