Why do my lasers do this?

[timber]

I have experienced this with green lasers bought from China. 5mW to 30mW pen types.

If the batteries are left in overnight, the next day the laser does not work well (it is not as bright as usual).

Also, if the laser is turned on for 1 minute, the laser loses power after 1 minute.

Is this a heating issue or something? Only happens with the green lasers I have bought.

Very confused by the power loss simply by leaving the batteries in over night.

Thanks.

 

[Blord]

Did you measure with a DMM if there is a connection between the poles of the laser if the laser is off ?
Normally the pen lasers won't drain power when it is off.

 

[Cel]

My greens sometimes need to heat up a bit, then they work much better.

 

[timber]

Did you measure with a DMM if there is a connection between the poles of the laser if the laser is off ?
Normally the pen lasers won't drain power when it is off.

Just tested it both the green pens.

Yes, there is a short between spring and case.

Any idea how I go about fixing that?

The two are different designs and I aborted my first attempt at twisting the driver out of the casing because the switch was stopping rotation.

EDIT - NO there is no short circuit from spring to casing - at least not now. I think I slipped with the probe twice.

So, back to the problem - batteries are still fully charged in the morning if they have been left in the pen (so no short circuit or fire!), but the laser only works properly after taking the batteries out and then re-inserting them.

Laser will work for a few mins and then grow dim again - hence my thought of something overheating?

 

[danefex]

Try carefully bending & centering the spring so it's not touching the case when batteries are installed

 

[timber]

Try carefully bending & centering the spring so it's not touching the case when batteries are installed

Yes, thanks.
The sponge around the spring does seem to stop that happening.

the strange thing is that I cannot leave batteries in my green lasers but I can in my red lasers.

If I unscrew the green lasers, test the batteries, they are still 1.5V, so there appears to be no drain or short - I am stumped.

 

[timber]

scientific test - sort of.

So I let the laser pen rest for five minutes in two pieces with batteries isolated.

Then re-assemble.

Operate laser for 20 seconds and bright green dot gets dimmer and then disappears.

Take batteries out for five mins and repeat - same results - strange.

As for second problem of batteries being left in overnight and laser not working until unscrewed and reassembled - I have to investigate.

I will cut up my first pen (because I don't know how to dis-assemble it properly (they all seem to be assembled differently - some screw in and some are pressed in)and isolate the driver and diode and see if I discover anything.

2 green lasers from seperate sources and same problem - what are the chances of that?

I thought it may have been an expected problem, but I will now start to investigate a bit more.

It is fun after all.