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So has anyone benchmarked batteries at freezing temps?


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I've done some searching around on here and so far the general consensus both here and on sources like Battery University is that the lower the temperature, the worse a battery's performance is. I know from my own experience that in my GPSmap 76S, Alkalines last barely even half as long at 50 degrees as they do at 80+ degrees. However, since I've pretty well abandoned Alkalines entirely now, I'm more interested in NiMH. So has anyone tested them before at cold temps?

 

If not, well, feel free to put in your wager on how long my set of Powerex 2700's will last during a 200mAh discharge in a C-9000 in my refrigerator. Yes, it's a synthetic test, in that it's taking place in a discharge device and not an actual GPS unit, but only because I can't seem to get signal lock from within my fridge, nor can I maintain good temperature control of my back yard to generate completely repeatable results.

 

batt03.jpg

 

So this particular set of batteries has about 7 sets of charge/discharge cycles on them and last reported capacity around 2550mAh per cell on average. They'll be due for a full recondition in a couple more cycles, but based on an approximate 2550mAh at 75 degrees, what does anyone think they either should (via scientific calculation) or might (based on personal experience) show as their capacity when they run out? Are there any tables showing temperature to deliverable power for the average NiMH out there?

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I've done some searching around ...

Interesting test; I'll do a similar one using an external antenna on my 60CSx; I'm running a a pair of eneloops through the C9000 in the R&A mode right now, to make sure they are topped off. When I ran a test with freshly charged eneloops earlier, I got 17.2 hours.

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I've done some searching around ...

Interesting test; I'll do a similar one using an external antenna on my 60CSx; I'm running a a pair of eneloops through the C9000 in the R&A mode right now, to make sure they are topped off. When I ran a test with freshly charged eneloops earlier, I got 17.2 hours.

Not sure why you would care unless you are leaving your gpsr out in the cold . The colder it is the less time you will spend out in the cold with your gpsr . I suppose winter camping might be a issue or if you leave your batteries in your car over night .

Throw 2 batteries in each pants pocket problem solved . Double A's are small enough so keeping them warm with your body heat is no big deal .

Cell phone is a bigger problem Shirt pocket for that one . And if your are going for days . I have a solar charger that has 2 built in AA batteries that is wallet size and fits nice and warm in my Back pocket .This doubles as a cell phone backup battery as well as a charger .

If your out in the cold that long a bigger worry is hands, toes, and ears . After 17 or 20hrs of exposure

most cachers have had enough cold I would suspect .

Edited by LECTRAGLIDE
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That's a great idea with the external antenna, now I kind of wish I had one. It's also good to hear data from another unit besides my 76S. I think the newer ones are supposed to have longer battery life, right? I just threw all my current findings online, here's a link:

 

http://www.sporksports.com/brandon/2008-02...tery_test.shtml

 

My longest duration in "normal" mode was 17 hours on the 2700's. I am still testing a set of Eneloops, although at a different temperature. Until the current temperature test is completed and/or your testing is done, I still won't know for sure how much of a difference the temperature makes in battery life. I may just end up re-doing my GPS testing from a window inside the house so I can have test data with all the samples being known at the same temperature.

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Not sure why you would care unless you are leaving your gpsr out in the cold . The colder it is the less time you will spend out in the cold with your gpsr.

Bicycle geocaching.

 

bike02.jpg

 

The GPSr sits up on the bars where it's wind-blasted with the outside air temperature, which in my parts is a relatively mild 50 degrees or so. Good enough that I get by with just long pants, a sweatshirt, and a warm beanie under my helmet to cover my head and ears, but cold enough to have problems with alkaline cells performing a lot worse than at 80+. I can do a good 2 hours or so like that, riding a caching along the way. I realize that not many people do that however, and the ones that do seem to be more partial to just using disposable lithium batteries instead, since they are well known as the top dog cold weather cells.

Edited by SporkSports
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It's also good to hear data from another unit besides my 76S. I think the newer ones are supposed to have longer battery life, right?

I just reviewed some measurements I made about 2 years ago using 2500 mAh Duracells. At that time I got 12 hours on my B&W Vista, 29 hours on the 60CS, and 20.5 hours on the 60CSx; this would compare to your 14 hours on the 76S with 2500 mAh Energizers.

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Not sure why you would care unless you are leaving your gpsr out in the cold . The colder it is the less time you will spend out in the cold with your gpsr . I suppose winter camping might be a issue or if you leave your batteries in your car over night .

 

Some of us use our GPS for more then just geo caching. I use mine for hunting too which generally starts out at around 18-20F in the morning and may warm up to mid 30's or lower 40's if it's a heat wave. I have two other friends that toss theirs in their back pack while snowmobiling so they can track their trip when they get home and those GPSr have seen -20F in the morning warming up to a balmy -5F in the afternoon. One of the guys uses alkaline in his Magellan eXplorist BW (screen) and the other uses 2400mAh NiMH in his Garmin Quest and both are getting over eight hours of continuous use.

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Lithiums generally last longer at lower temps in my experience. I'm out mountaineering, snowshoeing, and snow camping all winter. I've been on many multi-day trips where the temperature never got above freezing for three days. My Colorado 400t lasted 27 hours on it's first set of lithiums all while operating between 10F-25F.

If you are using other types of batteries your best bet is to take two sets and keep one set as close to your body as possible. Then swap them every time the cold set runs out of juice. Duct taping under your armpit will keep the warmest. Some people tape hand warmers to their extra batteries, but this gets expensive. Sounds funny but anyone who shoots video in cold temps with those custom NiCd or NiMh batteries knows this is the only way to be able to keep shooting.

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How does high temperatures, say 140 degrees F or more affect battery life for ni-mh and alkalines? This past summer I was out all day with my 60CSx and when I got back to the car the batteries were pretty low, so I put in a set of ni-mh that I had charged up the day before, but there were pretty much dead, they had been in the hot car all day. I put in a set of alkalines that I thought were good but they were dead also. They had been stored in the car for a few months.

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Results are in; average between the 4 cells was 2333 mAh, or about 90% of what they deliver at room temperature. I'm actually very pleased with the result.

My results were a little lower using the 60CSx: I got 14.3 hours in the refrigeration with a pair of eneloops, vs. a previous 17.1 hours at ambient temperature. The battery capacities as measured by the C-9000 were 2% lower for the refrigerator test, so I factored that in to come up with an overall 85% number. It's possible that the external antenna increases the battery drain slightly; I've heard this in the past, but never measured it (the refrigerator test used the external antenna, but the ambient test didn't). When I get a chance I will run an additional ambient test with the external antenna to check this out.

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Great results, looks like for two of the most common NiMH, the discharge ability is 85-90% as high around 35 degrees as it is at room temperature. In my view, that is still excellent performance.

 

In a related note, I did a little research on lithiums and the most common one, the Energizer Lithium is rated at 2900mAh at 1.5 volts. If the true average voltage over its full discharge is 1.3 volts, then we can estimate they'll put out around 3.77 watt/hours of energy. Compare to a 2700 NiMH at 3.24 or 2000 NiMH at 2.4 watt/hours. If the lithium still holds effectively at 100% efficient at 35 degrees and the NiMH drops to 85%, then the NiMH drop to 2.75 and 2.0 watt/hours. Still respectable, IMHO, but it becomes clear lithium holds a substantial advantage at low temps. I'll still keep my NiMH, but if I was going somewhere without the ability to bring spare batteries, then I guess lithium is the way to go.

Edited by SporkSports
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I've done some searching around ...

Interesting test; I'll do a similar one using an external antenna on my 60CSx; I'm running a a pair of eneloops through the C9000 in the R&A mode right now, to make sure they are topped off. When I ran a test with freshly charged eneloops earlier, I got 17.2 hours.

Not sure why you would care unless you are leaving your gpsr out in the cold . The colder it is the less time you will spend out in the cold with your gpsr . I suppose winter camping might be a issue or if you leave your batteries in your car over night .

Throw 2 batteries in each pants pocket problem solved . Double A's are small enough so keeping them warm with your body heat is no big deal .

Cell phone is a bigger problem Shirt pocket for that one . And if your are going for days . I have a solar charger that has 2 built in AA batteries that is wallet size and fits nice and warm in my Back pocket .This doubles as a cell phone backup battery as well as a charger .

If your out in the cold that long a bigger worry is hands, toes, and ears . After 17 or 20hrs of exposure

most cachers have had enough cold I would suspect .

 

I still think a better bench mark is your self . How long can I stay out ,Biking ,HUNTING ,hiking ,

geocaching in cold weather? Even a power sucking gpsr on battery save mode will last 8 or 10 hrs

. Six double a batteries take up less space than my samsung cell phone . And only weight slightly more

than my cell phone . So 2 batteries in the gpsr.=10 hrs . Plus 6 spares is 70 hrs of contant wandering lost in the wilderness . . My gpsr will last 28 hrs under perfect conditions . Sleeping and resting = power off . Get the smallest cell phone case you can find fill it with batteries ,put it on your belt so some body heat

protects them from full cold and you can hunt ,walk ,wander lost for a week .

Edited by LECTRAGLIDE
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How does high temperatures, say 140 degrees F or more affect battery life for ni-mh and alkalines? This past summer I was out all day with my 60CSx and when I got back to the car the batteries were pretty low, so I put in a set of ni-mh that I had charged up the day before, but there were pretty much dead, they had been in the hot car all day. I put in a set of alkalines that I thought were good but they were dead also. They had been stored in the car for a few months.

Generally for batteries, you want to store them at cold temperatures to help retain their charge, but use them at warm temperatures for maximum run time.

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