Cold temp battery performance?

[harebawl]

I just built a new light using a 5w wxot emmitter. I tried it out and it wow, but a few hours later, after the light was in my truck a few hours, about 0-5 degrees out, I turned the light on and it just didn't seem as bright as it was earlier...I checked the current draw, and it was only 800 ma, I brought the light inside and warmed up alittle for about a half hour, then checked current again and now I was getting 1.5+ amps....

I know alk. batts are poor in cold, but what about any of the rechargables....I'm running 5-6 c cells, so I prefer not to run lithiums.....how about the duracell ultras??? or Nimh???

Thanks, Harebawl

 

[stringj]

Only lithium cells give good cold weather performance.

Jerry

 

[RussH]

How many, and what size cells are you using? As Jerry said, only the lithium batteries are good in cold. But I wouldn't use the lithium AAs or NiMHs with a Lux5 that is drawing 1.5 amps on alkalines. You probably need to regulate that puppy a little tighter if you want it to last. My MR-X is regulated to 1.5amps and even so, I'm not expecting normal life (500hrs.?) even with the excellent hotlips heatsink. Or you might see what current it draws with 5 lithium or NiMH cells +dummy if needed. Lithium cells get kind of expensive in this sort of application. So do Lux5s.

 

[HarryN]

I tried to scan for a C cell replacement in 3 x AAA, but did not find it. Maybe someone else knows of one that fits. I personally like the C cell size, but 3 cells in parallel might have a better ability to maintain voltage under load when cold. (guessing)

I am not aware of anyone making C size Li cells, but it may be a specialty product for someone.

Silverfox and I had this very discussion the other day on how to do some cold weather testing of cells. It is not so difficult to do down to 0 F, but colder temperatures require a little more sophistication - or testing in Maine. /ubbthreads/images/graemlins/smile.gif

 

[RussH]

Harry, Saft makes some high discharge (not the backup type) D cells so I'm pretty sure they would have a C size, too. I don't think 3xAAA would come close to C in capacity or voltage drop, but you could use the Eveready lithium AAA. Three of those would be cheaper than a Saft C ($15 ea.?) and certainly better in cold than alkaline. Before we had lithium, nicads were used in cold weather, although you had to allow for their reduced capacity. Normally you would warm them up before use in really cold conditions.

How cold do you need to go? I'll bet there is info on the net for this, either at the battery manufacturers or universities, and military, if you could find it.

 

[IsaacHayes]

1.5amps on alkaliens means if you use Lithium or NiMH/NiCAD you're going to push way more than 1.5 amps through that luxeon and it will die fast.

My experiences with NiMH is that the cold doesn't affect them like alkalines, but it may some...

If you go other than alkaline, then do use some resistance. Radioshaq sells some .47ohm 5w wire wound resistors that would do good, maybe not enough though???

I used a .5ohm for my 5w V2T green and it pulls only 700ma from alks or NiMH. So your "T" vf may be lower or perhaps .5 is too much resistance for 1amp drive?

 

[hank]

Mountaineering outfitters have sold lithium 1.5v "flashlight" batteries, C and D size, for years -- they must still be available, for cold weather outdoors use.

 

[PeLu]

[ QUOTE ]
hank said:
Mountaineering outfitters have sold lithium 1.5v "flashlight" batteries, C and D size, for years

[/ QUOTE ]

The only lithium chemistry having these low volatges and I'm aware of are the LiFe cells with ~1.7V.
These are only available in AA and now AAA size.

All C and D cells (Lithium, high load) I know, are either LiMno2, LiSO2 or LiSOCl2, all of them in the 3V range.

Mountaineering shops (and dog sledge shops) use to offer mostly LiSO2 cells (SAFT and Everready).
I got a Roosa light some 20 years ago and used it down to -26°C with good results.

And yes, there are C cells, I do have Panasonic ones and there are SAFT.

 

[Lurveleven]

How about using the Energizer L91 Lithium batteries (these are 1.5V AA batteries) and using AA to C/D converters (i.e. one AA replaces one C/D).

 

[HarryN]

I suspect for the application, 3 V Li cells in C size would be fine if they are available. This would enable use of a shorter battery tube. (3 Li cells instead of 6 alkalines)

The AAA to C converter might be OK if it is 3 each AAA to C.

 

[HarryN]

Ok - I found C size Li cells - for some reason, had not looked at the obvious places. Batterystation.com and savin4u.com both carry SAFT and other Li C cells - nominal 3 volts.

They are a little spendy (around $ 15 / each) but they should solve your cold weather problem and now you will only need a 3 C length battery tube to run your Lux V.

These cells have quite a lot of "kick", so you might want to read up on them before buying them.