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Battery Question


Jim W

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That's not uncommon. Much depends on the capacity of the rechargables. Some can provide higher currents than others, and that makes a big difference depending on the power demands of the kind of device you are using.

 

Also, rechargables self-discharge at a higher rate than disposable alkalines. It can be 3% to 5% per day depending on the temperature.

 

If you leave a rechargable battery in a hot car for a few weeks, it will die (if not dead already) sooner than an alkaline in the same situation.

 

George

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Well I like alkaline batterys in the cold and they do last longer.

However NiMH batteries last 3/4 as long a fresh alkalines, I mean I can get a day of caching out of them even in the cold. So I always replace them before I go out and carry a fresh set, four that is, in my warm inside pocket.

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Can't argue that point Desert Warrior, I didn't know if it was my unit or if others noticed this issue, I'll just carry a spare set of alkaline in my backpack for emergency use, along with another set of Ni-MH.

 

Jim W

KD6EO

Exactly what I do. If you are like me - you might think of this.

 

I consider batteries sorta like ammunition. The more weapons systems using the same size bullet, the less different kinds you have to carry with you.

 

EVERY electronic item I carry with the exception of my digital camera and cell phone uses AA batteries. This is my ham radio, my FRS radio, my emergency beacon strobe, my mini-mag light, my transistor radio, and my GPS unit. This is 16 AA batteries in all. I keep 6 Ni-MH 2200 mah batteries in my ready-pack, along with 4 industrial alkalines. Should I get stranded, I can take batteries out of any unit to use in any other unit. Interchangeability is a desired thing, if you can make it work. In the desert, there is no convenience store! ;)

 

I really wish the digital camera was AA too. But it is AAA, so I carry 4 AAA spares too. I used to have a beacon strobe with a D cell with one D cell spare, and a c-cell mag light with 3 c-cell spares. Glad that those heavy suckers got replaced. I am looking at MP3 players right now, and most seem to use AAAs, so that will lessen the AA load a bit when the transistor radio is gone.

 

Yeah, I carry a lot of gear. If you don't bring it with you, you won't find it in the desert. Mostly, I carry it for the dumb fools I find out on the trails. Serious desert hiking isn't something people should take lightly. :P:D:D You are only a break-down away from disaster, and 15 miles from the nearest road can be too much sometimes!

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Yeah Mike, you think like I do, almost all my gear uses AA batteries, I have 12 sets of 4, and 4 battery chargers, I camp and hike with my wife and daughter, so we have 3 FRS radios (they aren't hams) 4 digital cameras, all but one takes AA, and 2 external flash, flashlight Mini Q40, and GPS V ... We should buy stock in a battery company ;)

 

Jim W

KD6EO

Edited by Jim W
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Renegade Knight, I was out yesterday with the GPS V for about 3 hours, I had the GPS on all the time, no battery saver, and when I got home I check the little battery indicator and it was down to less than 50%, don't know how accurate the indicator is.

 

Jim W

KD6EO

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Desert Warrior's ideal of using all AA batteries for your devices is good. I also use them on as many things as possible.

For a neat AA to D cell converter, go here: Aventrade

It will take from one to four AAs (in parallel) and let you use it in D cell applications. Whats fun is to put 3 of these with just one AA in each in a 3-D cell mag light and see how light it is.

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DomHeknows, I'm using Rayovac 2000mA 15 minute rechargeable, and they work great, haven't seen any of the 2300mA

 

Jim W

KD6EO

I'm using the ray-o-vac 15 min rechargables also. They are working fine for me. I also use the GPS V. Did you change the battery type in the menu setup. This compensates for the lower battery voltage of rechargable batteries, and makes the battery meter more accurate.

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Renegade Knight, I was out yesterday with the GPS V for about 3 hours, I had the GPS on all the time, no battery saver, and when I got home I check the little battery indicator and it was down to less than 50%, don't know how accurate the indicator is.

 

Jim W

KD6EO

I think the indicator is fairly accurate for Alkaline but not quite as accurate for NiMH's.

 

Like has been pointed out in this thread I've also standardized. Everything uses AA's or D's (Large Mag Flashlights). It's one reason I've not gotten one of the innova LED lights. They have a non standard battery.

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Rechargables are much more difficult to figure out how much life they have left vs alkalines.

 

The voltage in alkalines goes down slowly over time. Rechargables have a voltage that stays fairly constant, but then drops sharply near the end of its charge.

 

That means monitoring voltage alone isn't as accurate for the rechargables. It's even harder since you don't even know how much charge they had in the first place.

 

More advanced battery monitoring software trys to take other things into account...essentially trying to estimate just how many electrons have moved through the battery. It's still hard, though, since you don't know how many there were to begin with.

 

What you really need is some intelligence in the battery or battery pack. I think the 15-minute Ray-o-Vacs are an example of this. Each battery has it's own chip. I'm not sure if these somehow communicate with the charger itself.

 

Personally, I think battery technology just isn't getting where it needs to be fast enough. I'm hoping small fuel cells will make an economical debut soon.

 

George

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Here is what I came up with after curiosity got the best of me. These results should only be viewed as a relative guide… it was not a scientific test. Some of these batteries have been on many trips and some (Duracell 2050) are brand new. The conditions were a GPS 5 with an external mighty mouse antenna and the batteries went straight from the charger (1 hour type) to the GPS. The V was left on until the batteries quit and then the G-5 timer was read out and reset for the next run. The percentage value is relative to a new set of standard Duracell coppertops. The end cutoff voltage on my G-5 is 1.07 volts. The 2000 mAh Coppertop number is arbitrary. As with all batteries the run time is very dependant on the discharge rate so you can "make" numbers depending on the the cell is expected to be used.

 

As far as battery gauges go for NiMh batteries, that is a tough one. The discharge curve for NiMh is very flat. After the “surface” charge is gone the operating range is approximately 1.2 volts to 1.1 volts and when they hit the end they drop like a stone. The 1.07 volt cutoff in my G-5 is very close to 1.1 volts and I am guessing that it was chosen with the 1.1 volt drop out point in mind.

 

Anyway for what it is worth here is what I recorded.

 

GPS Battery Timer Rating Run Time Min Tot End Voltage=1.07V

Coppertop 2000? 15hrs 18min 918

Duracell 2050 14hrs 52min 892 97%

Radio Shack 1600 11hrs 56min 716 78%

Powerex 1800 11hrs 4min 664 72%

Ray-O-Vac 1600 9hrs 55min 595 65%

Monster 1800 13hrs 1min 781 85%

Powerex #2 1800 9hrs 34min 574 63%

Duracell 1800 10hrs 36min 636 69%

Duracell #2 2050 13hrs 2min 782 85%

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I have some seat-of-the-pants observations. My GPS uses two AAAs. I bought some of the new energizer NiMH, which are 750 mAh. They seem to last pretty much just as long per charge as an alkaline. Maybe not quite as long, but substantially longer than what was available just two years ago. I have no regrets about going to the recharables. I have two sets, plus I keep a spare alkaline set around just in case. The only odd thing about them is that the battery meter can't always make up its mind. If I leave it on a long time, it will show one out of four segments. If I shut it off for a while, it will come back with three segments, then after a while show two segments.

 

My digital camera takes 4 AAs, and I just bought one set of the 2100mAh rechargeables. Man, it's night and day between those and the old 1200mAh ones I'd been using. These new ones seem to last and last.

 

As others have mentioned, the downside is that NiMH batteries lose a good percentage of their charge every day even when they are not being used, so it's good to keep them in the charger until close to usage time.

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It is wonderful how rechargeable battery technology is catching up to primary cell performance (lithium cells push that bar higher but that is another story) to where the two systems are almost equivalent. It used to be with NiCads that yes you could recharge them hundreds of times but they would go flat so fast that it almost wasn’t worth the bother. Now with NiMh cells the two are so close that I get “sticker shock” when I have to go out and buy batteries for clocks and smoke detectors! And when it comes to very high current demand products like digital cameras the NiMh is hands down the winner. Match the battery to the application is the guideline I would say.

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