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Disposable Lithium Batteries


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We have two eTrex Vistas, which under normal circumstances used to give nearly identical readings. Sometimes when they were running low on battery strength, they'd vary by as much as 100 feet from each other, but if we put fresh batteries in both, they'd be back in sync.

 

Recently on one of them I tried out the Eveready disposable e2 lithium batteries. (I switched the battery type to "lithium" on the System page, and recalibrated the compass, as instructed.) Battery life was excellent, as advertised: it stayed at full power the entire time I had the batteries in, even while the other Vista went through a couple of sets of alkalines.

 

However, we started noticing a gradually increasing discrepancy between the readings on the two Vistas, even when the alkaline Vista had a new set of batteries. We brought in a third GPSr as a tiebreaker -- an eTrex Venture. It consistently agreed with the alkaline Vista, so it appeared that the lithium Vista was steadily losing accuracy (although it still claimed to be a full battery strength). Then, even more disturbingly, it began to take longer and longer to acquire satellites after powering on -- sometimes up to 10 minutes, while the alkaline Vista locked in less than one minute.

 

I switched the lithium batteries out for alkalines, and the discrepancy disappeared almost immediately. The variance dropped from over 100 feet down to about 20, and after half an hour, they were reading almost exactly the same again. The slow-satellite-acquisition problem also eventually went away (although for some reason, they will rarely lock on the same set of satellites, even when sitting side by side).

 

Has anyone else seen anything like this with the eveready disposble e2 lithium batteries? Does anyone know if the "lithium" setting on the Vista is intended only for lithium rechargeables, and not disposables? Is the battery-strength indicator on the Vista reliable when using this type of battery?

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It sounds like the Lithium Batteries were starting to die. Li batterie have a longer life, but they do not die slowly, Alkaline batteries die on a slow curve while Li batteries die on a vwery fast curve.

 

Another plus for Lithium batteries aside from useful life is their low weight which is great for back packers, and also their long shelf life (10 years)

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Glad someone is chiming in on this. I normally would not use the lithiums, for activities in my area (I am planning on using a set of the 'new' MAHA rechargeables. But I thought that having a 4 pack of AA lithiums in the car might come in handy at some point.

 

The extra cost is generally not worth it to me, except as JohnnyVegas pointed out, the lighter weight can help (some of us aren't so young anymore :P )

 

But I've noticed in some lights I use, the same battery curve. High power and the same light output, right till they are almost dead, and then they tend to drop off really quickly. I'm guessing this was a possible culprit also.

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That's interesting that you're finding accuracy variations related to battery strength. I've played around with an assortment of different units measuring and recording accuracy and never noticed any difference.

 

As for lithiums, the different battery settings don't affect anything other than how the battery meter functions. As JohnnyVegas mentioned, the different types of batteries have different discharge voltage characteristics, thus you need to let the electronics know what sort of battery it is so it will know what to base it's battery charge estimate on.

 

I sometimes take disposable Lithiums with me while backpacking. Mostly because the longer life means I can get away with fewer spares, and because I'm often get in fairly cold temps for part of the time while backpacking and the Lithiums don't seem to mind this at all. NiMh batteries are getting so good now though that my use of the Lithiums has gone down considerably. They do tend to be a bit expensive.

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The Lithium AAs do make good emergency backup batteries and are also good for cold weather use, but generally too expensive compared to rechargable NiMHs to be worth it for normal usage.

 

You'll find the same constant voltage until very close to dead discharge curve for NiMH (and NiCd) cells as you do for these Lithiums although the voltage is different (about 1.2 V for NiMh & NiCd vs. 1.6 V for Lithium). Since Hermit Crab reported that the Vista was still reporting nearly full battery voltage, this seems unlikely as the cause of the reported loss of accuracy and satellite acquisition. Unfortunately it's not uncommon for two nominally identical GPS receivers to behave quite differently even when they're in close proximity, so it's hard to draw any conclusions from a limited set of observations. I've tried on a few occasions to check for voltage-related performance variations on my GPS receivers (eMap, III+, 12) by repeatedly switching back and forth between new alkalines (@1.55 V/cell) and almost discharged cells (@1.0 V/cell) and have never been able to verify a consistent difference.

 

Another possible cause for the discrepancy would be that one of the Vistas may have somehow gotten an error in its recorded almanac of satellite orbit data. This would lead to longer acquisition times and possible loss of accuracy (partly from fewer satellite locks) until the unit was able to acquire a full corrected almanac. If the error happened to occur while the new Lithium cells were being tried then it would be easy to mistakenly attribute the performance problems to the type of cell.

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Thanks for all the replies -- interesting reading. I had been afraid that the lithium batteries might have somehow fried or damaged the internal workings of the Vista, if they were somehow operatig outside of some range that the Vista was expecting.

 

Given how much they cost, and the fact that they were not accurate for any longer than regular alkalines were (alive and reporting to be fully charged, and yet slow and inaccurate), I doubt that I'll use them again.

 

(peter's post about the possibility of the Vista losing its recorded almanc of satellite data was intriguing. I didn't know such a thing could happen, or that it would eventually correct itself. I wonder if that is what happened -- the behavior I saw did seem to fit that description.)

 

Thanks.

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It would be interesting to watch the voltage reading on the different batteries.

 

There is a test screen on my Legend.

If I hold in the "clickie" joy stick button when I power up the Legend it goes to the test screen.

 

The test screen shows battery voltage reading, like 2.8 or what ever it is.

The test screen also shows some other cool info.

 

Once you have the test screen up you can also press the page button and it test the screen, everytime you press page button it goes to another screen test page.

 

To get it out of the test mode, just power the unit off and back on.

 

The test screen maybe of some help in testing different batteries.

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Glad to see that folks have chimed in with their experiences. I will try out the everready "Energizer" lithium AA cells, they seem to work well in some of my other gear, and are definitely lighter in weight than many other batteries.

 

As other have mentioned, normally they are just too expensive for casual use, but I plan to use them during events (where I can't stop and pick up spare batteries, let alone recharge the nimh variety).

 

For "normal" use I plan on the Maha "powerex" 2300 cells, and probably will get the c-401FS charger. I imagine that I'll get some use from the 12v recharging there too, when the lithiums aren't needed.

 

As noted in other posts, these lithium cells do not tend to taper off gently, they stay pretty strong until just before the end. It's pretty evident in the DL-123 cells in some surefire flashlights I use, as well. (good power, then maybe 5 minutes of reduced light, before nothing . . .)

 

I have found the lithium cells to last longer than standard alkalines, we'll have to see how they fare in a 76CS.

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Atlantagal is running a test with lithiums that is being reported in the main forum in this thread. She is "currently" at 46.5 hours on her 76C and still showing 4 bars. No report of loss of accuracy, but she is not running it side-by-side with another unit, AFAIK.

 

(OK, I admit it. "Currently" is a strecth in a thread relating to electricity, but I couldn't help it.)

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I didn't realize I could possibly change the "battery type" in my GPS unit's menu. Will have to see if I can indeed do that so I can at least get a more accurate battery meter while doing my e2 lithium test.

 

I have noticed some difference in accuracy from time to time, but never thought to blame it on the lithium batteries. I figured it is just the position of the satellites/tree cover/etc. Also, the 76C reads differently that my prior Legend did. Usually if you get within 20-30 feet, you need to let it settle down for a minute or two. Then it seems to get a more accurate reading. Where my Legend would just walk you right to the cache with no pausing involved.

 

I also wanted to add that I have noticed using regular duracell copper top batteries, in both a Legend and 76C, the accuracy declines as the battery reaches 2 bars or less. So I can support that theory. I usually replace batteries at 2 bars for that reason.

 

Edit Added... My only choices for battery type are Alkaline and NiMH. There is no selection for any other type on my 76C. Oh well.

Edited by AtlantaGal
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On battery type selection does anyone know why the 60 and 76 do not have the option to select anything other than Alkaline or NiMH whereas my old vista allowed several different ones; can't remember exactly what they were but I could select Lithiums. To remove this function seems a retrograde step to me.

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Ive had a bit of experience with Lithiums, they were best used in a high drain item like the Garmin GPS III, that only lasted UP TO 8 hours MAX using 4 Alkalines, but lasted 32 hours on a 4 pack of Lithiums.

 

Seems like ive had issues with the Lithiums in other LOW battery drain items.

 

The Discharge curve of NiMH Rechargables, and of Regular Alkalines, discharge probably are easier to track in the software of the GPS than Lithium batteries.

 

I don't know if anybody ever tried measuring the Current drain of the batteries as the different types of batteries depleat in the GPS units??

 

If you wanna know why a GPS does poorly after a few hours of using the Lithiums try this experiment:

 

1) cut a strip of cardboard, about the width of a AA battery, and about an inch long.

2) Next cut 2 pieces of Aluminum Foil that is NOT AS wide as the strip of cardboard.

3) Glue one piece of the Aluminum Foil on each side of the strip of cardboard.

4) Next Stick this strip between a battery, and the battery spring, and tape the batteries down, without the battery door.

5) This will break the circuit for use with a Digital Volt Meter.

6) Take the Digital Voltmeter and put it on the 200 miliamp scale, and stick a meter probe on each side of the cardboard strip.

7) When you turn on the Meter it completes the circuit, then turn on the GPS.

8) As the GPS goes from 4 bars to 3 bars to 2 bars to 1 bar, note what the current drain is, from the batteries.

 

It could be that the Lithiums are NOT delivering enough current to the GPS as the batteries run down, so as why the GPS performs so poorly ???

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Atlantagal is running a test with lithiums that is being reported in the main forum in this thread. She is "currently" at 46.5 hours on her 76C and still showing 4 bars. No report of loss of accuracy, but she is not running it side-by-side with another unit, AFAIK.

 

(OK, I admit it. "Currently" is a strecth in a thread relating to electricity, but I couldn't help it.)

I'm going to cross post this, but..

 

She's unofficially running side-by-side with my units - Rino 130 using Duracell M2's and a GPSMAP 60CS running NiMH 1800's.

 

More detail in that thread that you quoted.

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For "normal" use I plan on the Maha "powerex" 2300 cells, and probably will get the c-401FS charger.

Just noticed recently that Energizer has out 2500 mA AA NiMH batteries. I found them listed here:

 

[http://www.thomas-distributing.com/energizer-aa-nimh-rechargeable-batteries.htm]

 

I currently have several pairs of various 2000 and 2300 mA AA NiMH batteries that have worked well for me. I've used them in my GPS unit, digital camera, reading light, flashlight, etc. I also have a Maha charger that I like.

 

I usually pack an extra pair of AA alkalines when I'm out and about just in case.

Edited by Ferreter5
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