Suppressors Crimson Trace Question

[Prairie Dog Dundee]

I recently put Crimson Trace laser grips on two of my hand guns. One on a S&W 3" Model 60 357 mag and the other on a Kahr CW9 9mm. These two grips take different size batteries. The laser on the Kahr is much brighter than the laser on the S&W.
Is this normal? Do the lasers get dimmer as the battery runs down?

Thanks in advance for the help.