Battery question

[iceNsnow]

Lithiums have a rectangular discharge curve--that is, the voltage stays constant until the battery is fully discharged and will drop down in only a few minutes. (The cell is essentially exhausted at this point.) So, if a lithium cell is somewhat discharged, it will simply shorten the run time, but the voltage should be ok until the end.

Doug

DougPaul? Does this mean that the battery indicator level on my gps when I use lithium batteries will register FULL for a very long time and then one day will be EMPTY all at once?
Thanks so much,
Inge

 

[Neil]

Inge, you betcha it'll die quickly. One minute it's alive and kicking, the next it's as dead as a door nail. What the hell is a door nail, btw?

 

[DougPaul]

DougPaul? Does this mean that the battery indicator level on my gps when I use lithium batteries will register FULL for a very long time and then one day will be EMPTY all at once?

Pretty close. You will be happily using the gps (with the battery indicator at full) and and it will drop off and die within a few minutes. (The shelf life of lithiums is pretty good (~10yrs), so it isn't likely to lose much charge when not in use.)

Those battery gauges only work well with alkalines, because then voltage drops as the battery discharges. Lithiums, NiMHs, and NiCads all have rectangular discharge curves.

To look on the "bright" side, a headlamp with a lithium, NiMH, or NiCad battery will hold full intensity until the end. The intensity of LED lights, in particular, will taper off when using alkalines. (This is how they list such rediculously long run times--by a long taper into a very dim light.)

Doug

 

[iceNsnow]

I KNEW it!!

Thanks DougPaul! Yeah, I always wonder how my headlamp would be in that 70th hour........

As for you Neil! How about you find some of those doornails and climb Haystack w/ me?! I changed my criteria so that if you can't hike fast, can't be a laugh-a-mile, but can carry a doornail, your good!

 

[skidoc22]

Don't know how good your charger is--some of them almost guarantee that you will damage NiMH cells in typical use. Or it may not be charging them fully.

I have a 1hr charger which overheated and damaged some of my cells. If you have a 15min charger, it should be used only with cells specially designed for it--it will likely damage any other cells.

I have used NiMH rechargables in my headlamps, digital camera, and GPS in winter. Haven't had any problems yet...

You might consider carrying lithiums as backups. Lightweight and should work if the NiMHs fail.

Doug

I have unfortunately used the 1h rayovac charger on these batteries a few times - perhaps they are now damaged. I have tried to recondition them with the smart charger but they only seem to last a fracton longer. So it seems I now have to start from scratch with new batteries and only use the smart charger.

I do bring the lithiums as backup for the camera, gps and headlamps.

 

[Kevin Rooney]

battery indicator level on my gps ...

If you're concerned about getting the most accurate reading on your GPS, set the GPS battery type indicator to reflect the one loaded in the GPS. Don't change the charactoristics of the battery though.

 

[DougPaul]

I have unfortunately used the 1h rayovac charger on these batteries a few times - perhaps they are now damaged. I have tried to recondition them with the smart charger but they only seem to last a fracton longer. So it seems I now have to start from scratch with new batteries and only use the smart charger.

Rayovac PS4 by any chance? That is the one that overheated some of my NiMHs. Its (AA) charging current is about 1800 mA in the NiMH setting and 900 mA in the NiCad setting. 1800 mA is too much for many AA cells, but 900 mA is fine. (Its NiCad setting is also ok for NiMH AAA cells.) For comparison, the MH-C401FS is 1000 mA (fast)/300 mA (slow) and the MH-C204F is 500 mA.

Don't think that reconditioning will help NiMH cells that have been damaged by overheating. Its primary purpose is to erase the memory effect in NiCad cells. Occasionally useful in NiMH cells which are far less subject to the memory effect.

Doug

 

[DougPaul]

If you're concerned about getting the most accurate reading on your GPS, set the GPS battery type indicator to reflect the one loaded in the GPS. Don't change the charactoristics of the battery though.

Just changes the scale factor--doesn't give you any more information. Since I use alkaline, lithium, or NiMH cells in my GPS, I just leave the battery type set to alkaline and remember which type is in use. A full NiMH will read about 1/2 -- 3/4 full on the alkaline setting. (Alkaline is the proper setting to use for lithium batteries.)

AFAIK, the battery type setting doesn't affect anything except the readout.

BTW, my eTrex Vista shuts down when the battery voltage drops to about 2.0 V. This is high enough that the batteries are protected from reversal damage. Presumably other GPSes have a similar shutdown voltages.

Doug

 

[skidoc22]

I have a Magellan Meridian but I have never seen a way to change the battery type setting.

 

[skidoc22]

Rayovac PS4 by any chance? That is the one that overheated some of my NiMHs. Doug

Ps4 it is...

 

[DougPaul]

Ps4 it is...

Ay-up! A number of people have had problems with that one cooking the batteries. Just set the switch to NiCad and it should be ok. Otherwise, it is a good charger. Still use mine every now and then.

The comments about battery type setting were Garmin-centric. Don't know about other manufacturers. If you don't have a setting, just assume it is for alkalines and don't worry about it. (See my earlier comments on how I leave the setting at alkaline.)

Doug

 

[slowmo68]

I found a great way to keep my devices from freezing up in the cold, just put in the device case a chemical handwarmer ( mini ) but also something in between your device and the warmer (cloth , etc ) I have never had a problem with the electronics not working when using this method. And near the end of hike you can grab out the warmer(s) to use on your hands if needed.

 

[DougPaul]

I found a great way to keep my devices from freezing up in the cold, just put in the device case a chemical handwarmer

Generally not needed. Probably more important to prevent condensation on GPS antennas and anything with moving parts.

I have just kept my electronics (camera and GPS) cold and dry--no problems so far. (I think this is what most people do.)

Lithium batts are good to ~-40, but some electronics may fail to operate before it gets that cold. Cameras are subject to ice in the moving parts or on the optics.

Garmin specs for one of their GPSes are: 5F--158F (-15C -- 70C). My Canon digital camera specs are: 32F--104F (0C -- 40C). Both have worked for me below their rated minima. If the device fails to work at temps below ~0F, then the chemical handwarmer might be worth a try. (158F/70C is too hot for some batteries...)

BTW, the above temp ranges are operating ranges, storage ranges are generally somewhat wider. The GPS range is an "outdoor" range, the camera range looks like an "indoor" range. (There are "indoor" and "outdoor" rated LCDs. The GPS range essentially matches the display ratings--it is possible that something other than the display limits the temp range for the camera.)

A salesman told me that the camera LCD display can crack in the [presumably extreme] cold, but he was trying to sell me an insurance policy. I am not aware of any specific instances of this ever happening.

Just searched out some LCD specs:
* operating: 0C -- 50C, storage: -20C -- 70C
* operating: -20C -- 70C, storage: -30C -- 70C
No guarantee that these numbers apply to the displays in our GPSes, cameras, other electronic toys, but they do suggest safe temp ranges.

Doug

 

[Pete_Hickey]

A salesman told me that the camera LCD display can crack in the [presumably extreme] cold, but he was trying to sell me an insurance policy. I am not aware of any specific instances of this ever happening.

Just searched out some LCD specs:
* operating: 0C -- 50C, storage: -20C -- 70C
* operating: -20C -- 70C, storage: -30C -- 70C
No guarantee that these numbers apply to the displays in our GPSes, cameras, other electronic toys, but they do suggest safe temp ranges.

I have extensive with a small LCD in cold. The one on the little compuer attached to my bike. I store it outdoors always, so it has eailsy gone down to -25F over the past few years.. (before global warming, I didn't have a computer on my bike).

One thing I notice in the cold, is that it is rather slow to change. By cold, I would say that it really gets noticibly cold at around -10F. At colder temperatures, the distance feature is almost useless. The time it takes for a segment to warm up and display, is longer than it takes me to go the distance which causes it to change.

Once the weather gets warmer, it functions fine. The cold has no lasting effect.

 

[DougPaul]

One thing I notice in the cold, is that it is rather slow to change. By cold, I would say that it really gets noticibly cold at around -10F. At colder temperatures, the distance feature is almost useless. The time it takes for a segment to warm up and display, is longer than it takes me to go the distance which causes it to change.

Once the weather gets warmer, it functions fine. The cold has no lasting effect.

The slow response effect is easily observed by putting an LCD digital watch in the refrigerator. (LCDs have moveable molecules in a liquid--the cold induced change in viscosity is the cause of the slow response.)

The above is a short-term effect of the cold. I would like to find out if there is any risk of permanent damage from the cold.

Doug

 

[Pete_Hickey]

...in the refrigerator.

Refrigerators (even freezers) are not that cold.

The above is a short-term effect of the cold. I would like to find out if there is any risk of permanent damage from the cold.

As I mentioned, I leave my bicycle out all winter. We have (not this year) weeks of below zero (F) temperature, and usually a month of below 0C temperature.

I have noticed no ill effect on my bike's computer display. This has been over, at least, five years with the current computer.

 

[DougPaul]

Refrigerators (even freezers) are not that cold.

Not cold enough to stop a watch display, but cold enough to slow it. (IIRC, I've demoed it using my freezer.)

As I mentioned, I leave my bicycle out all winter. We have (not this year) weeks of below zero (F) temperature, and usually a month of below 0C temperature.

That global warming screws up all sorts of things...

I have noticed no ill effect on my bike's computer display. This has been over, at least, five years with the current computer.

Thanks--I had noted your -25F datapoint. It would make sense for a bicycle computer to use an outdoor-rated display.

Doug