AAA size 3.7 volt batteries in ebay pens seems great?

[Antharak]

I ran a QQtech 650nm pen for 5 minutes at 9v with no signs of damage, it got hot and that was it.
I didn't have an LPM at the time so I don't know what effect it had on the output.

 

[MajorLim]

When you notice your laser dimming at an alarming rate it's because your blowing the laser. I once tried a 9v with a 3v laser. It got super bright then died extremely fast.

Er... running a 3v device with 9v battery will do that.. it probably shagged the driver first... then when it successfully killed the driver it then probably killed the diode.
They are talking about 3.7v... that probably won't kill the driver. It might get slightly warm, but its not much over the 3v required.
Don't put 9v through anything that doesn't need nine volts... I've seen some drivers that will take 9v. But they get hot and need heatsinking.