Laser Pointer - How much juice ?!??!?!

[toryglen-boy]

i got a 40mw laser pointer this week, i havent even used it more than 3 mins (and thats no exagerationm, i havent had the chance to point it skywards yet) and the beam is dying in intensity ... i am guessing batteries

is this normal ?!??!?!


:shrug:

[g__day]

Duncan

Short answer - No. With Lithium batteries (AA or AAA) in that it should last a long time - so I'd wonder is there a short draining the batteries when the laser isn't active. Either test if there is any current flow (i.e. non very high resistance with it switch off across the contacts) or see if a second set of batteries goes dim after being in the pointer - but with it not switched on for a day or two.

Matt

[astronut]

Duncan,
Yes, it could be the batteries packed with your laser.
They may be of insufficient capacity or just plain old.
Use only fresh Lithium batteries.
Lasers don't like the cold, anything lower than about 12C makes the beam fade.
If you're hand holding the laser, I suggest that whilst not being used it's kept in your pocket where it's kept warm by your body heat.
If it's mounted on your scope, you will have to gently heat the laser body to help keep the laser operational, this can be done with a eyepiece dew heater.:thumbsup:

[toryglen-boy]

Hi John

yeah, i thought that might have something to do with it, as it was near the back door all weekend catching the wind, and was icey cold. i got it up to body heat and the beam got much stronger. It came with duracell batteries, but could have been lying there a while. Can you recommend a good battery for them? are rechargeables any good?

thanks

[erick]

Are they AAA? Anyway, lithium would give the best performance. But I have used rechargeable lithium hydrides, but recharge them regularly.

Energizer lithiums should perform well - for the $s.

Just don't put a pile of them in your pocket to fly to the US:-

"The United States Transportation Security Administration (http://en.wikipedia.org/wiki/Transportation_Security_Administrat ion) announced restrictions effective January 1, 2008 on lithium batteries in checked and carry-on luggage. The rules forbid lithium batteries not installed in a device from checked luggage and restrict them in carry-on luggage by total lithium content."

I gather they aren't the original supplied battery? My new Citizen watch went "funny" after about ten months. Supplier replaced the battery, no cost to me, and promised I'd be OK and it has been fine since. I read the fine print in the manual and it says the battery supplied with the watch will not give normal battery life!

[toryglen-boy]

Hi Eric

Yeah, they are the original supplied batteries, so that could be the culprit, although they are Duracell ultras. Dick Smiths has a pack of 4 AAA Lithiums for $20.

seems like a good purchse.

:thumbsup:

[erick]

Check the local supermarket first - might save a dollar or two?

[OneOfOne]

Here's my solution to flat batteries. I got a 4xAA battery pack from the local electronics store and voltage regulator and bits to make a voltage regulated supply. At room temperature it puts out 3.00V. If I put it into the freezer for an hour or so, it outputs 2.98V. The batteries have a much higher capacity than AAAs and they need to drop to about 4.2 volts before the regulator will "drop out". The hardest thing was taking to the laser with a hacksaw to cut it down and gain direct access to the circuit board inside.

[toryglen-boy]

well, i put lithium batteries in there, and they are very good, but it appears the main culprit is the ambient temperature of thing. if i keep it warm then its all good

:thumbsup:

[Starkler]

Duncan, keep it in your pants pocket when observing and you'll be fine.

[OneOfOne]

When the ambient temperature drops to single digits the laser basically stopped working. I was told by the supplier that it is probably the batteries getting cold, hence the battery replacement. So I put the whole unit in the fridge and the battery voltage barely changes...and the laser barely works. If I put it in the freezer, the battery voltage is still ok, but the laser is totally off. Because my unit attaches to the tube for alignment and for showing people "where we are looking" I can't really put it in my pocket. But with the increased capacity, and much cheaper battery replacement cost, I can leave it on for 30 seconds or so and the laser will warm up and become visible :)

I have another laser that I keep in my pocket for handheld usage.