Need to replace batteries but want to switch type

I have an older xeon style handheld strobe I picked up at auction. When I first got it, it was charged and worked but it didn't come with the charger so eventually it died. Let it sit for a while and finally opened it up to see what power source it had. It has three "D" cell sealed lead acid batteries (2 volt cells).

I bought a cheap multi-voltage wall charger and after correcting for the proper polarity on the charging plug, have it charging but it seems to barely be taking a charge as even after a couple hours I press the trigger and I get maybe one flash, a Lo-Batt msg and then nothing. My guess at this point is that I have essentially destroyed the old lead-acid batteries by leaving them dead for so long.

I have found replacements on amazon but wanted to see if it was viable to replace the old cells with a newer technology i.e. ni-cad, ni-mh, etc. I know that I would have to use more cells to achieve the 6 volt level but I could use smaller cells to fit in the same compartment.

The big question is, how likely is it the same circuitry would properly charge the alternate type of cells? I can take pics of the circuitry if this would be helpful.

Thanks for any input in this,

Doug

 

Thanks for the input!! Not really wanting to get into modifying or adding anything so will stick with plan A and get the lead acid batteries. Figured it wouldn't be a simple swap but wanted to get some more knowledgeable input.

Thanks...