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Questions Regarding Rechargeable Batteries


G & C
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I'm sure that these have been answered before, but a search yielded no clear results. Sorry if it's been asked recently.

 

I just picked up a Garmin Oregon 550, and I decided to give the rechargeable batteries a whirl. In my Colorado 400t, it eats up alkaline batteries daily.

 

I carry a backpack everywhere I go, and on it a case for 8 spare batteries. If I want to put the charged rechargeables in that case, will they hold charge for long? Couple of weeks, maybe a month at most? I don't want to be out and about and find that the batteries that I have waiting in the queue are not holding a charge and be left with no power...

 

Also, how do the Garmin rechargeables that come with the Oregon 550 stack up to Duracell and Energizer rechargeables?

 

And last, which rechargeable batteries do y'all recommend?

 

Thanks in advance!

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I don't like to leave my Eneloops sitting for more than 3 months, and my normal NiMH for more than 2 weeks. I've never actually done any measurement and observation, so that's just my gut feel and take it for what it's worth.

 

I suggest carrying a couple of alkaline or disposable lithium cells in addition to 4 NiMH (preferably low self discharge NiMH) for backup instead of carrying around 8 NiMH.

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The low discharge batteries, enloops and others, retain a charge for nearly a year. The standard high capacity batteries are fine for a couple months.

Standard NiMH batteries self-discharge at a rate of about 0.7% - 1% per day.

 

After 60 days, that means that you have between 55% and 65% of your original charge.

 

I won't let them sit for longer than about 2 weeks.

 

Li-Ion batteries are much better, and, if you have a good GPS unit, you can recharge the batteries in it without having to remove them at all!

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I don't like to leave my Eneloops sitting for more than 3 months, and my normal NiMH for more than 2 weeks. I've never actually done any measurement and observation, so that's just my gut feel and take it for what it's worth.

 

I suggest carrying a couple of alkaline or disposable lithium cells in addition to 4 NiMH (preferably low self discharge NiMH) for backup instead of carrying around 8 NiMH.

 

This was my initial thought, just out of paranoia. Maybe a set of four of the nice lithiums, and then the four rechargeables in addition to the two that will be in the GPS.

 

I think I need to find myself a good battery dock that will work in the car.

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As a battery engineer, I've done extensive testing on the enloops as well as some of the other branded low self discharge batteries. The enloops will still give 80-85% of the original charge after 1 year storage at room temp. I use them almost exclusively in all my devices now, even in the remote controls. The only time I don't is when I need low temperature performance, in which case I use the primary lithiums.

 

Get a couple of packs and a good charger (4-6hr charger, not a fast charger!) and you'll get lots of life out of them.

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...Li-Ion batteries are much better, and, if you have a good GPS unit, you can recharge the batteries in it without having to remove them at all!
I like this idea but can only think of a few GPS units (DeLorme PN-series and Magellan Explorists) that do this. Are their others? Edited by lee_rimar
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I've used the Rayovac hybrid batteries in my SLR and GPS, they're low-discharge NiMH. I've had good results out of them and they're relatively inexpensive.

 

Don't forget a good charger. I'm currently using a very basic charger, but I've got my eye on one of the "smart" chargers that monitors each individual battery instead of just slamming current through 2 at a time.

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2nd the Rayovac Hybrids. I'm still using the first ones I bought about 4 years (Maybe more?) ago. Of course they don't last as long as they did, but they still hold up fairly well. Before then, I tried Energizer rechargeable, they didn't last very long though. When some of my R'vacs were stolen in a car break in, (4 that were in my Geobag) I bought some Duracells. They did about as well as the Energizers. I just bought some Eneloops, and so far I'm impressed.

I use a MaHa charger in my car.

JM.02W

PP4x4

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Well, everyone has an opinion. Mine appears to go against the mainstream in this thread so I'll toss it in for variety and thought.

 

I have been a user of rechargables for years, first NiCads and NiMH for the past few years. I did it because it's supposed to be the green thing to do and it's supposed to be cheaper, too. At least if you believe all the hype out there. I didn't really question it much. I just started doing it and kept on. With the NiMH I have researched batteries and chargers. My present setup is a Powerex Maha MH-C9000 charger, a set of four Sanyo Eneloops and a couple sets of Sanyo 2500mAh.

 

They're free to anyone who wants them.

 

I'm done with rechargables.

 

They make no sense for the way I use them. I go for short, intense periods of use in my cameras and handheld GPS .. typically vacation time .. and then they sit for long periods with only occasional casual use.

 

The conventional NiMH are never charged when I need them. Or I charge them multiple times between uses in order to have them ready when needed. Even the Eneloops generally discharge more than I like between uses. Yes, the self-discharge rate is slower but they start with considerably lower energy to begin with (1900mAh vs. 2500mAh), so it's almost a wash. In either case, if I want fully-charged batteries any time I need them, they get recharged multiple times between uses.

 

That just makes no sense. I'm wasting energy. When I'm not using them, I'm going through rechargable batteries at about the same rate as if I was actually using them. The price I paid for the gear and batteries I have right now would keep me in conventional alkalines for four or five years. The money I've spent on chargers and batteries in the past four or five years would keep me in conventional alkalines for the rest of my life.

 

So I've retired my Maha charger and spent 13 bucks for a 48 pack of alkalines from Costco. That will keep my camera and eTrex Legend HCx going for many many months at a whole lot less impact, overall, on the environment and a bunch less money out of my pocket.

 

One man's opinion. Think about your personal usage patterns, then do the math regarding the monetary costs and think about which will have the larger impact on the environment: the number of alkalines you will consume in a given period versus the resources to build and operate your charger and rechargable batteries and the price you will pay for them.

 

The answer might not be as obvious as you assume. Or are pressured to believe. It turns out that the answer depends entirely on your usage patterns.

 

...ken...

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It turns out that the answer depends entirely on your usage patterns.

Quite true, it all depends on usage.

 

In your case. I'd forget about the hybrids, set the MH-C9000 to rapid charging, and charge the 2500 mAH in 1 to 2 hours right before they are needed. Sure, it's tough on the batteries, but even if a pack of 4 costing $10 lasts 100 cycles, $10 / 400 = 2.5 cents is cheaper than $13 / 48 = 27 cents. I haven't measured how much energy the charger consumes in recharging 4 batteries, but I'm pretty certain it is way below 1 kWH (4 x 2500 mAH holds a total of less than 15WH of energy). The baseline charges here is $0.19 per kWH. 50WH (horrible inefficiency) translates into less than 1 cent on your utility bill (assuming you don't go above baseline).

 

The amount of energy spent in recharging the cells is a few orders of magnitude less than that required to manufacture or recycle the alkaline cells. In many applications the lower internal resistance allows NiMH to function significantly better than alkalines in high drain devices. I know this is true in cameras, I don't know if this is true for GPSr.

 

I'd ask for the charger, but I see the cacher from my neighbor city already did :unsure: Besides, I already have a good charger.

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It turns out that the answer depends entirely on your usage patterns.

Quite true, it all depends on usage.

 

In your case. I'd forget about the hybrids, set the MH-C9000 to rapid charging, and charge the 2500 mAH in 1 to 2 hours right before they are needed.

Ah yes ... wouldn't it be wonderful if I knew 1 to 2 hours in advance of when I need them?

 

My wife never says "Dear, I will need the camera in 1 to 2 hours to take a picture when I'm expecting our dear sweet twin grandchildren to do something incredibly cute!" Thoughtless and ill-prepared woman that she is, it's always "Oh look what the twins are doing ... bring the camera quick!!".

 

My mouse is equally inconsiderate. There's no 1 to 2 hour battery warning light. It just quits without warning.

 

My bicycle riding buddy does occasionally give me a half hour warning (when he doesn't just drop by for a ride). But I usually need to scramble to get ready to go and charging batteries isn't top-of-mind when I grab for the eTrex.

 

So, in anticipation of one or more of the above events, or similar, I end up just recharging them on a regular basis. Usually just so they can sit and discharge again. Just as the ones in the devices in question are discharging as the devices sit there doing nothing most of the time.

 

The world is a thoughtless and disorderly place.... :rolleyes:

 

...ken...

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Ah yes ... wouldn't it be wonderful if I knew 1 to 2 hours in advance of when I need them?

You did say "typically around vacation time" in your original post. Unless you're one of those people who goes "honey, let's go off to Hawaii/India/Tanzania/Antarctica right now!" I'd guess you have some advance notice :huh: I'm also a little shocked that in between the times your grandkids do something sweet and incredibly cute, your batteries have time to discharge - c'mon, you're grandparents! You're supposed to find them cute all the time! :P

 

The world is a thoughtless and disorderly place.... :rolleyes:

No argument from me there.

 

Anyway, to assist you in anticipating such events, here's a link.

Edited by Chrysalides
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Thanks Chrysalides,

 

That tip was perfect for my situation. It will help me prepare for the next time my wife says, "Honey, we've got three days before I have to babysit the twins again. I need an Ikea fix." The nearest Ikea is a little over 500 miles away. When she says something like that we're usually packed and out of the house in a whole lot less time than it takes to charge batteries. <_<

 

...ken...

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