Hey, I can't find much info elsewhere on what I am doing and figured there are some electrical gurus that frequent these forums so I hope it's ok to post a non rc related question here anout batteries.

Here's what I did. I have a set of porter cable cordless power tools that run on 18v lithium ion packs. The packs state that they are 1.1 ah on the sticker which I think means the pack is made up of 1100 mah cells (18650 cells). I ordered some panasonic 3400mah cells which is the highest capacity 18650 size cell currently available. I removed the 5 1100mah cells from my porter cable pack and replaced them with 5 of these panasonic cells thinking I should get about three times the run time on my tools.
Is there any reason that shouldn't be the case? I ask because I was running a tool today (reciprocating saw) with the modified pack and after a few minutes of continuous running it suddenly acted like the pack had died...my second pack that still has the stock cells in it ran a lot longer without issue and when I put the modified pack back into the same tool a hour or two later it ran again like it had plenty of power, although I didn't run it for long.

Is it possible the electronics pcb in the battery pack will only work correctly with 1100mah cells? is there some difference between 18650 cells besides just the capacity?

any info on this would be great