AAA NiHM or alkaline batteries for green pointer ?

[partylighter]

I have three 50mW lasers twom from DX and one from o-like. All threec are powered by 2 AAA batteries. When I try alkalines all three work fine.
When I try NiMH it is dependant on the type: fully charged it works best but one DX is still rather dim.
I measured the current : the alkalines (open circuit voltage 1.51 V per battery) draw over 200mA (as expected) but not fully charged NiMHs less than 100mA while the OC voltage is 1.37V per battery.

Does somebody have experience with NiMH versus alkaline AAAs ?

 

[Blord]

I always use NiHM for lasers. No problems with it.
I played so much that rechargeable batteries are economical in the long run. I save the alkaline batteries for remote controls and clocks

 

[Kevlar]

Personally I would stick with alkaline, a little more voltage. I can't find them right now, but I've read a few threads on which alkaline batteries give the best results, you would just have to use the search.

Also, IIRC, Jack, the owner of Optotronics, recommends alkalines as well.

 

[Benm]

Things that work with alkalines but not nimh's are bullshit devices if you ask me.

Sure, the starting voltage of an alkaline cell is somewhat higher, but if the laser craps out under 1.2 volts, it would not drain much of the batteries potential capacity at all.

 

[RA_pierce]

Things that work with alkalines but not nimh's are bullshit devices if you ask me.

Sure, the starting voltage of an alkaline cell is somewhat higher, but if the laser craps out under 1.2 volts, it would not drain much of the batteries potential capacity at all.

Amen to that.
If it won't run on NiMH, the regulation is garbage.
The pump diode only needs ~300mA at 2.2V, so there is no excuse.

 

[Cyparagon]

I think alkalines are about 60-70% empty at 1.2V. Whether you should use NiMH or Alkaline depends on how low of a dropout the driver has.

I thought the diode needed lower (1.7V?) but if it is indeed 2.2, that's not much room for a linear (the vast majority of greens) driver to do it's thing.

 

[anselm]

Unfortunately, that's how all ultracheap AAA greenies i've had (22 ebay, 2 DX) seem to (mal)function....

I thought the diode needed lower (1.7V?) but if it is indeed 2.2

Maybe the "driver"s Vf = 2.2 - 1.7 =0.5V ?

 

[RA_pierce]

I think alkalines are about 60-70% empty at 1.2V. Whether you should use NiMH or Alkaline depends on how low of a dropout the driver has.

I thought the diode needed lower (1.7V?) but if it is indeed 2.2, that's not much room for a linear (the vast majority of greens) driver to do it's thing.

Most of the 808nm pumps I've played with want 1.8-2V, and the higher power ones ~2.2V, so yes, it is sometimes less than 2V.

Also, my NiMH fresh off the charger will supply 1.3-1.4V each unloaded.
I have no problem using them in cheap greens from DX.

Either the batteries in question are no good or the laser has a terrible linear regulator. Most likely the latter.

 

[partylighter]

Another interesting test:

I bought two Varta NiMH 800 mAh Low self discharge AAA's.
I tested the 2 year old DX true 50mW with it and the just received O-like 50mW.
I did these batteries in one and the alkalines in the other. The result: regardless in which the new NiMH batteries were, the old DX was MUCH brighter than the O-like one.

And, of course the new NiMHs (out of the box without initial recharge) did much better than the old NiMHs I have.