Green laser pointer rated 200 mW. That is the laser beam output, the pumping infrared diode uses about 1 watt. Uses 2 AAA batteries. Problem is that it quickly drains the batteries, the batteries are dead after 3-4 minutes of use. To save money, rechargeable batteries are typically used. The problem is that common NiH batteries are rated 1.2 V, unlike the normal 1.5 V in normal batteries. Since the laser is designed to run on 3 V, but is only getting 2.4 V, there is a very noticeable drop in light output. It seems like the light output is reduced by 40-50 percent. The laser uses an infrared emitting diode, and just as with LEDs, a fairly small drop in voltage will greatly reduce the light output.
Rechargeable lithium batteries exist. I thought I saw 1.5 V AAA rechargeable lithium batteries somewhere online. They were rather expensive, and required their own special charger specifically designed for lithium batteries. Apparently a standard battery charger cannot be used because of fire danger, because it will overcharge the lithium batteries. 2 batteries and the charger were 35 dollars if I remember correctly. I cannot find the link now, this was over a year ago.
I clearly remember seeing them for sale somewhere online. I am absolutely sure they were rechargeable and not 3.7 volts... or maybe it was a single 3.2 volt battery and I am not remember correctly? Here's a 2-segmented 3 volt rechargeable lithium, presumably each cell is 1.5 volts:
The laser can operate with 3 NiH rechargeable batteries (3.6 V total). The beam is brighter, but I did not feel comfortable running it for more than a few seconds. Being a cheap chinese import, the diode is probably already overdriven, and the instructions said not to leave it on for more than a minute continuously. Something about overheating, it did get noticeably warm. Also the housing is not designed for 3 batteries, so it is rather annoying to have to precariously hold it in place.
This whole thing seems like a terrible design. They could have at least designed the housing to be thicker to use AA batteries.
I just wanted to mention this because maybe there are other people out there facing the same problem, or who are using rechargeable batteries and wondering why their laser is not putting out as much light.
Does anyone else have more information about standard shaped rechargeable lithium batteries, and where to buy them? They seem to be quite difficult to find and very expensive.
There are also NiZn rechargeable batteries rated at 1.6 V each.