why not rechargeables?

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why not rechargeables?

Postby Jeff Bartlett » 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.
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Postby NZcaver » Dec 17, 2007 11:04 am

:exactly: I'm with you on this!

But... I still can't resist playing a little Devil's Advocate as well. :devil:

If you're operating remotely for an extended period (think week long or more caving or wilderness expeditions), you may want to consider carrying (non-rechargeable) lithiums. They're not cheap, but they are the lightest weight battery technology available as far as I know. Of course if your headlamp or other device already uses custom Li-Ion rechargeable packs, then this is pretty much a moot point.
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Postby Jeff Bartlett » Dec 17, 2007 11:17 am

NZcaver wrote:If you're operating remotely for an extended period (think week long or more caving or wilderness expeditions), you may want to consider carrying (non-rechargeable) lithiums.

and i actually do carry some alkalines, an emergency spare set or two and a set in my emergency third source of light. i've never had to use either, so it would be a PITA to recharge extra sets of NiMHs every couple of trips for that purpose. alkalines do have their place, i just don't see it as being one's primary batteries.


NZcaver wrote:Of course if your headlamp or other device already uses custom Li-Ion rechargeable packs, then this is pretty much a moot point.

mine does :grin:
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Postby Squirrel Girl » Dec 17, 2007 11:53 am

NZcaver wrote::exactly: I'm with you on this!

But... I still can't resist playing a little Devil's Advocate as well. :devil:

If you're operating remotely for an extended period (think week long or more caving or wilderness expeditions), you may want to consider carrying (non-rechargeable) lithiums. They're not cheap, but they are the lightest weight battery technology available as far as I know. Of course if your headlamp or other device already uses custom Li-Ion rechargeable packs, then this is pretty much a moot point.
Lithiums are awesome! It depends on the device, but in my GPS, they thing goes like the Energizer bunny and never quits. In a headlamp, it lasted maybe 2-1/2 times as long.

I quit using the rechargables, but just too much to keep track of. My life is out of control enough as it is, let alone add that in. However, with the new hybrids that don't lose their charges, I think that would be a potential for me to reconsider. Now if you add in where I don't have to charge the things in pairs, I really might go for it. Somebody who knows should tell me where I can go for a hybrid NiMH that does single/2/3/4 battery recharging, and I'll buy them.
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Postby Jeff Bartlett » Dec 17, 2007 12:12 pm

Squirrel Girl wrote:Somebody who knows should tell me where I can go for a hybrid NiMH that does single/2/3/4 battery recharging, and I'll buy them.

there's a link in my original post to the charger i own, which is like $40. seems pricey, but it has an individual circuit for each cell, so it can charge any odd combination of batteries and doesn't need to be charging batteries from the same set since it doesn't shut off when one of a pair reaches full charge.

it charges each battery to its full capacity independent of the others in the charger, and keeps the temperatures cool so the batteries last a long time... the "fast" is about 100 minutes to charge the hybrid batteries (which are roughly 2100 mAh) and the "slow", which keeps them extra cool, is about 5 hours. supposedly it uses a charging algorithm that conditions the batteries and keeps them performing highly.

it also has a "trickle" charge feature where once your batteries are charged, it feeds them a very gentle current so you can leave them on the charger indefinitely and they will stay "topped off" without any detrimental effect on the batteries.

and it has a car charger and a carrying case to keep the mud off it =)

as for the "Hybrid" batteries, they're showing up everywhere now. any of the rechargeable batteries currently being sold as "pre-charged" are the ones you're looking for - i know you can commonly find the Rayovac, Duracell, and Energizer versions at various chain stores, and i even found a coupon for the Duracells in my local paper. just make sure you get the ones that say pre-charged; the "regular" NiMH batteries don't come charged because they won't stay charged during the unpredictably long periods of time they might spend on the shelf.
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Postby NZcaver » Dec 17, 2007 12:41 pm

That Maha is a nice charger! Worldwide voltage-friendly too. Great - something else to add to my wish list.
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Postby Scott McCrea » Dec 17, 2007 1:02 pm

Nice post, Jeff. Thanks for all the info!
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Postby ian mckenzie » Dec 17, 2007 1:24 pm

Like Barbara, I'm not capable of keeping track of something as small as a AA battery. If I lose my rechargeables at home, in the car, in my pack etc., I'm out some good cash, but if I lose an Alkaline, big deal - I have a desk drawer full of 'em. Not very 'green' I know, but there it is. Anyways, when I travel, I don't want to bother with a charger, current converter for different countries etc. when I can just buy Alkalines as I go.
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Postby NZcaver » Dec 17, 2007 2:21 pm

I hope you're not in the habit of losing "small" items like AA batteries in caves.

I have a lot of stuff and certainly lose things occasionally, but even I don't find it that hard to keep track of batteries. (No offense.) I keep sets of rechargeables in little baggies, ready to go. But if I ever need to buy alkalines in a pinch, it's nice have that option too.
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Postby Komebeaux » Dec 17, 2007 3:58 pm

NZcaver wrote::exactly: I'm with you on this!

But... I still can't resist playing a little Devil's Advocate as well. :devil:



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Postby ian mckenzie » Dec 17, 2007 5:31 pm

NZcaver wrote:I hope you're not in the habit of losing "small" items like AA batteries in caves.
Nar, wouldn't dream of it. I'm one of those annoying people who sweeps up after other cavers...

NZcaver wrote:I have a lot of stuff and certainly lose things occasionally, but even I don't find it that hard to keep track of batteries. (No offense.)
Oddly nuff, it seems like I only lost the expensive ones; the cheapies turn up all the time... Come to think of it, that was back when the kids were still living at home. Connection?
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Postby fuzzy-hair-man » Dec 17, 2007 5:41 pm

I use my caving headlamp to cycle between uni and home each day so my batteries stay in my headlamp, the night before the trip I put them in the charger and have nice full batteries the next day. If on the odd occasion I forget to put them in the charger the night before I can alway put them in in the morning and charge them in the car on the way to the cave.

NiMH batteries are also lighter than your alkalines :kewl: but for me the biggest advantage is going caving with a full set of batteries everytime :woohoo: No more running out of batteries half way through a trip or putting up with a dull light to get the last out of your batteries.
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Postby Squirrel Girl » Dec 17, 2007 11:07 pm

NZcaver wrote:I hope you're not in the habit of losing "small" items like AA batteries in caves.

I have a lot of stuff and certainly lose things occasionally, but even I don't find it that hard to keep track of batteries. (No offense.) I keep sets of rechargeables in little baggies, ready to go. But if I ever need to buy alkalines in a pinch, it's nice have that option too.

I have batteries all over the place. I have no idea if they are charged or not. I have a meter to tell, but that will take the effort of testing them. My truck has about 3 sets of 4 AAs taped together that say half used. I have one battery loose in the kitchen. I think it was being saved to recycle at work.

I've got s%^& all over the place that isn't put away or kept track of. Batteries, sheesh, the least of my worries. And tonight after working a 10 hour day, I had to drive 25 miles to a trail advocacy meeting. Twenty five miles home, and I'm finally checking up on my email and the web. What was I trying to keep track of???
:question:
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Postby NZcaver » Dec 17, 2007 11:41 pm

You think you got it tough? Just try picking up everything and moving home at least twice a year! :hairpull: Especially with me being a chronic gear and gadget junkie, and having a rare genetic condition that makes me predisposed to hoarding all sorts of crap!

Wait a minute - what was I talking about keeping track of again? Oh, shoot. :doh: Never mind. I'm moving again tomorrow. No really, I am. The only reason I'm posting is that I'm taking a breather from packing. And now back to work...
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Postby Squirrel Girl » Dec 18, 2007 7:21 am

It's my goal to sell a whole bunch of unused stuff I have to de-clutter my house, but I just haven't had time.
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