why not rechargeables?
Posted: Dec 17, 2007 10:36 am
there has been some discussion on this topic in another thread and i thought it certainly warranted its own thread.
Rechargeable battery technology has continued to advance, much in the way LED technology has advanced, now to the point where it seems to me that the reasons for continuing to use alkalines are few. However, I recognize that there are still quite a few people who prefer alkalines, including good friends in my own grotto, and I am curious as to why.
the arguments against alkalines:
(1) Rechargeables cost less. Let's say I spent $20 on a set of 8 Duracell rechargeable batteries, the regular 2650mAh ones you can buy at any Wal-Mart for my Princeton Tec Apex. Let's even say that I splurged $40 on a fancy charger that will charge them independently and keep them in tip-top shape (like this one). Since the functional life of these batteries is ~2 years (YMMV), we'll use that as a baseline.
Since we typically get around 10 hours per charge with this headlamp while primarily using the "4 high" setting, and slightly less with alkalines, most cave trips will require 1 set of batteries in the lamp and a backup set. and let's say that I go caving twice a month, for a total of about 25 trips per year, with trips averaging 8-10 hours and thus using one set of batteries each. Even if I buy the $12-for-32 Rayovac AA's at Wal-Mart, over the course of two years I will go through 200 batteries at this rate, which is 6.25 packages of 32, which will cost me $75.
In all likelihood, after the 2 years my rechargeables will be fine since they've been babied with my fancy charger, or only my "primary" set would be worn out. and even if they weren't, i could just buy another 8 batteries for $20 and be set for another couple of years, whereas with alkalines the cost will add up...even at a paltry $1.50 per trip.
(2) rechargeables "recover" faster. in my Sunpak 383 flash unit, the manufacturer specifies the recycle time with NiMH rechargeables as half the alkaline recycle time (source: documentation that came with the flash unit).
(3) rechargeables are significantly better with high-drain devices, including digital cameras and high-power flashlights/headlamps (which nearly all of us own and bring caving).
to quote wikipedia: "NiMH batteries are particularly advantageous for high current drain applications, due in large part to their low internal resistance. Alkaline batteries, which might have approximately 3000 mAh capacity at low current demand (200 mA), will have less than 1000 mAh capacity with a 1000 mA load. Digital cameras with LCDs and flashlights can draw over 1000 mA, quickly depleting alkaline batteries after a few shots. NiMH can handle these current levels and maintain their full capacity."
(4) rechargeables don't clog landfills. while many of us do recycle our alkaline batteries, many do not. using the figures cited for example (1) above, after 2 years a careless alkaline user has thrown away 200 battery cells. a rechargeable user has thrown away... zero.
the arguments against rechargeables:
(1) self-discharge. this has been largely resolved, as even with standard NIMH batteries the rate of discharge is between 5%-10% on the first day and then 0.5%-1% per day at room temperature thereafter (source: wikipedia.org)... so even 2 weeks after charging you have 75% of your battery life, and there's little reason to let them sit for a few days between charges anyway. if you're going on long expeditions or otherwise won't be near a charger, you can use the new "hybrid" type, which will hold a charge of 70%-85% after a YEAR.
(2) need to charge in pairs. this is also easily resolved with a good charger - there are several on the market that will charge your batteries individually, and most also include features to prolong the life of the batteries and optimize performance. it's worth the extra dollars to pick one up, especially if you have headlamps or other items that use an odd number of batteries.
now your turn. why on earth wouldn't we all be using rechargeables? i feel like i'm missing something.
Rechargeable battery technology has continued to advance, much in the way LED technology has advanced, now to the point where it seems to me that the reasons for continuing to use alkalines are few. However, I recognize that there are still quite a few people who prefer alkalines, including good friends in my own grotto, and I am curious as to why.
the arguments against alkalines:
(1) Rechargeables cost less. Let's say I spent $20 on a set of 8 Duracell rechargeable batteries, the regular 2650mAh ones you can buy at any Wal-Mart for my Princeton Tec Apex. Let's even say that I splurged $40 on a fancy charger that will charge them independently and keep them in tip-top shape (like this one). Since the functional life of these batteries is ~2 years (YMMV), we'll use that as a baseline.
Since we typically get around 10 hours per charge with this headlamp while primarily using the "4 high" setting, and slightly less with alkalines, most cave trips will require 1 set of batteries in the lamp and a backup set. and let's say that I go caving twice a month, for a total of about 25 trips per year, with trips averaging 8-10 hours and thus using one set of batteries each. Even if I buy the $12-for-32 Rayovac AA's at Wal-Mart, over the course of two years I will go through 200 batteries at this rate, which is 6.25 packages of 32, which will cost me $75.
In all likelihood, after the 2 years my rechargeables will be fine since they've been babied with my fancy charger, or only my "primary" set would be worn out. and even if they weren't, i could just buy another 8 batteries for $20 and be set for another couple of years, whereas with alkalines the cost will add up...even at a paltry $1.50 per trip.
(2) rechargeables "recover" faster. in my Sunpak 383 flash unit, the manufacturer specifies the recycle time with NiMH rechargeables as half the alkaline recycle time (source: documentation that came with the flash unit).
(3) rechargeables are significantly better with high-drain devices, including digital cameras and high-power flashlights/headlamps (which nearly all of us own and bring caving).
to quote wikipedia: "NiMH batteries are particularly advantageous for high current drain applications, due in large part to their low internal resistance. Alkaline batteries, which might have approximately 3000 mAh capacity at low current demand (200 mA), will have less than 1000 mAh capacity with a 1000 mA load. Digital cameras with LCDs and flashlights can draw over 1000 mA, quickly depleting alkaline batteries after a few shots. NiMH can handle these current levels and maintain their full capacity."
(4) rechargeables don't clog landfills. while many of us do recycle our alkaline batteries, many do not. using the figures cited for example (1) above, after 2 years a careless alkaline user has thrown away 200 battery cells. a rechargeable user has thrown away... zero.
the arguments against rechargeables:
(1) self-discharge. this has been largely resolved, as even with standard NIMH batteries the rate of discharge is between 5%-10% on the first day and then 0.5%-1% per day at room temperature thereafter (source: wikipedia.org)... so even 2 weeks after charging you have 75% of your battery life, and there's little reason to let them sit for a few days between charges anyway. if you're going on long expeditions or otherwise won't be near a charger, you can use the new "hybrid" type, which will hold a charge of 70%-85% after a YEAR.
(2) need to charge in pairs. this is also easily resolved with a good charger - there are several on the market that will charge your batteries individually, and most also include features to prolong the life of the batteries and optimize performance. it's worth the extra dollars to pick one up, especially if you have headlamps or other items that use an odd number of batteries.
now your turn. why on earth wouldn't we all be using rechargeables? i feel like i'm missing something.