Chart showing rechargeable battery life versus alkaline battery life in a high-drain application. Source: GreenBatteries.com
Dear Pablo: I'm a New Yorker who tries to be environmentally conscious. For years now, I've been confounded by rechargeable batteries. They just don't seem to work for me as I imagine they should....and now I'm at the end of my rope. Before I give up completely on this technology, I decided to write to see if maybe I just don't understand how they work.
I have battery-operated items throughout my apartment - clocks, flashlights, wireless computer accessories, Guitar Hero controllers - you get the idea. The obvious solution to my extensive battery needs was to get myself a whole bunch of rechargeable batteries - the "good" NiMH kind. I would simply make sure I kept a supply of these bad boys charged and handy at all times, and I'd never need to throw away another used AA battery! But it just hasn't worked out. Whenever I pick up one of my devices or one of my previously charged batteries, I can basically count on it being dead. I just don't understand.
Also, if it's environmentally toxic to throw away regular batteries, I have to assume it's even worse to throw away rechargeable ones. Can you give me a sense of the environmental impact of throwing away a regular battery vs. a rechargeable one?
Please help me understand; I really want to do the right thing. What type of batteries should I be using?
Like CFLs, rechargeable batteries have improved a lot over the years. I too have shared your frustration with them and continue to use alkaline batteries for some applications. After discussing how alkaline and rechargeable batteries work I will share some tips on how to maximize you experience with rechargeable batteries.
Batteries are a contained chemical reaction that gives off electrons. In Alkaline batteries this reaction occurs between zinc and manganese oxide with potassium hydroxide as the electrolyte. The effective capacity of an alkaline battery is between 700 and 3000 mAh, meaning that a digital camera using 1000 mA of electricity could theoretically run for up to 6 hours on two AA batteries. As batteries are used their voltage drops steadily from their rated voltage (1.5 V for AA batteries) until the voltage is too low to power your electronics. At this point, there is still electric potential available from the batteries, but not for high-drain applications like your digital camera. These batteries can often be used for several weeks in a TV remote, wall clock, or some other low-drain application. Alkaline batteries also store well and lose only about 2% of their charge per year, which is why many of them carry an expiration date many years in the future. Alkaline batteries used to contain mercury but are now considered, by many jurisdictions, to be safe for disposal in your regular trash. However, states like California classify alkaline batteries as hazardous waste that needs to be disposed of separately.
The most common Household rechargeable batteries are NiMH (Nickel Metal Hydride), Li-Ion (Lithium Ion), and NiCad (Nickel Cadmium). You may have also heard of lead acid batteries, which are used in cars and boats. Unlike alkaline batteries, the chemical reaction within rechargeable batteries can be reversed by applying electricity through an appropriate battery charger. This can be done 100-1000 times. Rechargeable batteries contain toxic and rare substances that should be recycled properly.
Rechargeable batteries can be charged over several hours but some companies also sell chargers that work much faster. You should always make sure that you are using the right type of charger with the right type of battery. Using a quick charger on a battery that is not designed to be charged rapidly may degrade its capacity and lifespan. Also, never try to recharge an alkaline battery as it may explode. Unlike alkaline batteries, rechargeable batteries have a high leakage rate, up to several percent per day. This can be decreased by storing them in your refrigerator or freezer once they are charged. Also, rechargeable batteries work much better in high-drain applications, which is why most digital cameras now come with built in rechargeable batteries, rather than requiring the continuous replacement of half-used alkaline batteries.
I recommend that everyone gets a good set of rechargeable batteries, and the appropriate charger. You can often find a good deal on a bundled starter kit that comes with a charger and a few batteries. Avoid using them in clocks, flashlights, fire alarms, and other applications where they will not last very long and instead use them in devices that use more electricity and get more use. You are right to want to switch to rechargeable batteries since it will cut down the amount of alkaline batteries that you throw away, but using them in the wrong application, storing them improperly, or charging them improperly will reduce their effectiveness. So remember, a rechargeable battery only reduces your environmental impact if you actually use them correctly.
Ask Pablo is a weekly column that aims to answer your pressing eco-quandries. Want to ask Pablo a question? Simply email Pablo(at)treehugger(dot)com. Wondering why Pablo's qualified to answer? As the Vice President of Greenhouse Gas Management at ClimateCHECK, he helps major corporations measure and manage their greenhouse gas emissions.
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