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Equipment Discussions >> Equipment

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hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: Green Laser Pointer new [Re: Jeff Morgan]
      #6043361 - 08/24/13 10:54 AM

Quote:

...my GLP works fine from 7500' MSL mountain tops in northern Arizona. You'd have to go to Antarctica to find cleaner and drier air!



My GLP works fine at 7,500' in NM (except when it gets cold). I'm 2,500' lower than MRO (2 miles from me), and 1,000' higher than VLA (20 miles away), and those locations were chosen for their low humidity.

I've tried GLPs in Antarctica. Even when kept in a pocket they don't work, but I would not expect their consumer-grade Li-ion batteries to work at sub -20F.

For our dark and cold stations that operate through the year, we use Lithium Thionyl Chloride batteries with hybrid layer capacitors (HLCs) to provide power during high current (mA, that's high for our gear!) demands. Even then we have to derate the batteries by 400%. We'll bury a ton of batteries in the ice to run the equivalent of a 5w bulb through the winter.

Remember that the "temperature" of a battery used in manufacturer's data sheets is the average temperature of the battery in the previous 24 hours.


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Howie Glatter
Vendor


Reged: 07/04/06

Re: Green Laser Pointer new [Re: hottr6]
      #6043851 - 08/24/13 04:00 PM

"If this is Glatter's "SkyPointer", it is powered by AAA batteries and no way will AAA deliver electrons when it gets cold (below 50F)."

www.energizer.com :
The recommended operating temperature range for alkaline batteries is -18° C to 55° C. . . The Alkaline-Manganese Dioxide cell can operate at temperatures as low as –20oC however this performance will be significantly lower. ."

Most of my pointers are highly cold resistant. I usually test them at 1 degree C.


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nevy
professor emeritus
*****

Reged: 02/07/12

Loc: UK
Re: Green Laser Pointer new [Re: hottr6]
      #6044036 - 08/24/13 06:21 PM

Quote:

Quote:

Quote:

Quote:

Mine works below freezing, you can stick mine in a freeza for 30 minutes and it still works , the beam is a bit spread out for a second or two but once the ice crystals are burnt off of the laser outer lense it's back to to normall thin beam , you gets what ya pay for.




Which brand / model is that?




I bought them from howie glatter.




That's interesting. If this is Glatter's "SkyPointer", it is powered by AAA batteries and no way will AAA deliver electrons when it gets cold (below 50F). Are you referring to another unit? I'd like to know what powers it, because even Li-ion chemistries fail when water starts to thicken.

The other explanation is that many British refrigerators are made by Lucas, "Prince of Darkness", inventor of the 3-position switch (on, off and flicker), so it is unlikely that your freezer works.




Trust me , it works in the cold, if it didn't then I wouldn't say so.
So everyone needs to stop using their telrad in the cold because they use AAA batteries because “ it is powered by AAA batteries and no way will AAA deliver electrons when it gets cold (below 50F)."

Edited by nevy (08/24/13 06:44 PM)


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nevy
professor emeritus
*****

Reged: 02/07/12

Loc: UK
Re: Green Laser Pointer new [Re: nevy]
      #6044039 - 08/24/13 06:22 PM

And my freeza works just fine too ;-)

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Robert Cook
sage
*****

Reged: 07/23/09

Loc: San Diego County, California
Re: Green Laser Pointer new [Re: hottr6]
      #6044134 - 08/24/13 07:45 PM

Quote:

That's interesting. If this is Glatter's "SkyPointer", it is powered by AAA batteries and no way will AAA deliver electrons when it gets cold (below 50F). Are you referring to another unit? I'd like to know what powers it, because even Li-ion chemistries fail when water starts to thicken.




Not to pile on, but here is a fairly convincing "torture test" (of a flashlight and its battery):
http://www.candlepowerforums.com/vb/showthread.php?321619-Zebralight-Torture-...

That's a standard 3V (nominal) Li-MnO2 cell, but in practice I've found 1.5V (nominal) Lithium AA and AAA cells using Li-FeS2 chemistry to be at least as robust (and probably even more so). Quality NiMH AAA cells (e.g. Eneloop) can also take a real beating and continue to function--50°F would be no problem for them.

Now, alkaline batteries (Zn-MnO2) aren't nearly as tough and can begin to sag (in voltage) and fail under adverse conditions, but well-designed circuits should be able to draw enough current from them to continue to function under most conditions that we'd be willing to subject ourselves to (without a parka). Devices that require a certain narrow voltage range and flawless battery performance may fail with alkalines when temperatures get chilly, however.


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hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: Green Laser Pointer new [Re: Howie Glatter]
      #6044990 - 08/25/13 11:13 AM

Quote:

www.energizer.com :
The recommended operating temperature range for alkaline batteries is -18° C to 55° C. . . The Alkaline-Manganese Dioxide cell can operate at temperatures as low as –20oC however this performance will be significantly lower. ."




I've tried 3 different sets from different production runs of this very same battery and they fold at 50F in my Z-Bolt. That's my experience.


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nevy
professor emeritus
*****

Reged: 02/07/12

Loc: UK
Re: Green Laser Pointer new [Re: hottr6]
      #6045243 - 08/25/13 01:51 PM

I use duracell , I've not had any problems with failure in the cold

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Howie Glatter
Vendor


Reged: 07/04/06

Re: Green Laser Pointer new [Re: hottr6]
      #6045439 - 08/25/13 03:53 PM

Hi Shane,

" . . they fold at 50F in my Z-Bolt. That's my experience."

Have you measured the current draw ? This is easy to do if you have a multi-meter current function with low series voltage drop (0.2V or less). Just remove the battery cap and put the meter probes to the battery and case.
Many sellers boost the drive current to get reasonable output from low-efficiency crystals and optics, but high current will disproportionately reduce alkaline cell
low-temperature performance (as well as give short infra-red laser diode lifetime).
If your current is 350 or more milliamps, that might cause the batteries to suffer in the cold. I run my pointers at around 260 ma.
I believe that variation in the quality of the optically active crystals with respect to energy conversion efficiency over temperature, is the biggest factor that kills low temp. performance.


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Green Laser Pointer new [Re: hottr6]
      #6046100 - 08/25/13 10:11 PM

Use lithiums.

- Jim


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MikeCMP
super member
*****

Reged: 07/12/11

Loc: Chardon OH
Re: Green Laser Pointer [Re: jrbarnett]
      #6046223 - 08/25/13 11:57 PM

Are there any GLP that run off of AA instead of AA? AA last way longer.

I think the reason the GLP's fail in the cold is most of the cheap ones are IR pumped. They need the heat in order or function. The best way for one to work in the cold would be for you to get a GLP with a diode,min stead of IR pumping. But, I think the green diodes are pretty expensive.

Mike


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hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: Green Laser Pointer new [Re: Howie Glatter]
      #6049066 - 08/27/13 03:14 PM Attachment (13 downloads)

Good tip Howie, I'll try that. Thanks.

I disappeared for a couple of days, but before I left, I popped my lasers into the fridge. I took two photos, one when I placed them in the fridge, and the other, 2 hours later.
The first photo on the left showed all three beams glowing brightly. After 2 hours, when the GLPs were turned on, they were momentarily bright for, I guess, half a second before going dim. The RLP was unaffected.

Then I popped them into the freezer for 30 minutes. The Z-Bolt did not light at all, and the Jasper was fainter still. The RLP remained unaffected.

Batteries: In the Z-Bolt, AAA Energizer "Ultimate Lithium" Li/FeS2. In the Jasper, CR123A Li/MnO2, and the RLP (actually, a collimator) AA Rayovac alkaline-manganese.

Hardly a scientific experiment, but this is typical of the tests I have done with different battery chemistries in these lasers, and all with the same results. The dimming after a brief time indicates something in the circuitry that is responsible.


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nevy
professor emeritus
*****

Reged: 02/07/12

Loc: UK
Re: Green Laser Pointer new [Re: hottr6]
      #6049460 - 08/27/13 07:01 PM

I don't think it's your batteries that are not working in the cold , I think it's the actual laser.

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MessiToM
scholastic sledgehammer
*****

Reged: 12/21/09

Loc: Huntingdon PA
Re: Green Laser Pointer new [Re: nevy]
      #6049591 - 08/27/13 08:16 PM

Yes its the IR laser diode that is pumping your GLP suffering ^

I just set mine to kill and she likes it! lol


Edited by MessiToM (08/27/13 08:17 PM)


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hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: Green Laser Pointer new [Re: nevy]
      #6050778 - 08/28/13 02:10 PM

Quote:

I don't think it's your batteries that are not working in the cold , I think it's the actual laser.



I'm thinking it is a combo of both. What I *think* may be happening (I'm no engineer!) is that the cold does effect the initial transient of current coming from the battery, which fools the circuitry into doing something different. I don't see the moderate cold effecting the laser circuitry because most consumer electronics is rated to near freezing, so I infer that my observations are due to how a battery reacts to rapid changes in load at different temperatures (there is a lot of quantitative evidence to back this up). Bottom line: The battery and laser circuitry are not well-matched.

I would wager that if I used a high-quality linear DC power supply we would not see GLP dimming with cold.


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hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: Green Laser Pointer new [Re: MessiToM]
      #6050911 - 08/28/13 03:32 PM

Quote:

Yes its the IR laser diode that is pumping your GLP suffering ^



Is there anything a mere-mortal can do to fix this? Is there a pot that can be adjusted?


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MessiToM
scholastic sledgehammer
*****

Reged: 12/21/09

Loc: Huntingdon PA
Re: Green Laser Pointer new [Re: hottr6]
      #6051763 - 08/29/13 12:42 AM

Yup ^ build a Direct drive diode laser rather than IR Pumping one

{link to 15mW diode deleted by moderator}

Edited by Jarad (08/29/13 09:48 AM)


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schwimmair
super member
*****

Reged: 09/13/10

Re: Green Laser Pointer new [Re: MessiToM]
      #6052160 - 08/29/13 09:25 AM

I have a cheap GLP (eBay special $6) and use a chemical hand warmer that I wrap around the battery compartment in the winter. Works like a charm and keeps your hand warm while in use. I like the hand warmers because they are non-toxic and cheap. You can get a 3 pack (6 hand warmers) at Wally World for $2.11. If you observe a lot you can also get a 20 pack (40 hand warmers) for $6.00.

Schwimm


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csa/montana
Den Mama
*****

Reged: 05/14/05

Loc: montana
Re: Green Laser Pointer new [Re: nevy]
      #6052184 - 08/29/13 09:46 AM

Quote:

So everyone needs to stop using their telrad in the cold because they use AAA batteries because “ it is powered by AAA batteries and no way will AAA deliver electrons when it gets cold (below 50F)."




Hmmm, my Telrad is powered by 2 AA batteries.


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Jarad
Postmaster
*****

Reged: 04/28/03

Loc: Atlanta, GA
Re: Green Laser Pointer new [Re: MessiToM]
      #6052190 - 08/29/13 09:49 AM

Quote:

Yup ^ build a Direct drive diode laser rather than IR Pumping one

{link to 15mW diode deleted by moderator}




Direct drive is fine, but you still need to keep it under 5mW.

Jarad


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Widespread
professor emeritus


Reged: 05/11/11

Loc: Bowling Green, Kentucky
Re: Green Laser Pointer new [Re: Jarad]
      #6052206 - 08/29/13 10:02 AM

MessiTom,

What the heck is that unit????

David


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