Alot of the older ones or newer ones?
I believe they have changed the drivers, I have an older style 50mw that runs fine a 3.7v cr123 (4.2v peak)
These are boost drivers and the more you put in the more you get out, so its not necessarily the driver you should be worried about, it the amount of current your diode is receiving.
Im not trying to be a know it all here, just re writing what has already been posted on the forum allready.
I am not familiar with new and old ones...
All I know is that there are shorter and longer modules overall (including PCB), which makes the olnger ones somewhat difficult to install in Jayrobs pen hosts, and they need modifications.
But I think I'll disagree with you on the boost converter.
Look closely on the PCB, there is no coil there what-so-ever,
This is a simple low dropout step down converter,
There is apsolutely no need to put boost converters in greenies as the IR diode requires no more than 1.9 - 2.0 V, and a great percent of commonly used boost converter drivers cut off at 2.7 V according to datasheets (LM3410X I am using can still operate down to 2.3 V but at that voltage it will pull just under 1A to power a PHR).
No purpose at using one....
I have tried powering it in my hand, the PCB after 2 minutes gets expectably warm, but not hot by any means.
We need an expert opinion on this however, because I am just taking an educated guess, not presenting facts (except the LM3410x).