Convert cordless drill from Ni-Cd to Li-ion conversion

[SentinelAeon]

Hello,

I have a couple of old laptop battery packs and i would like to do a fun little project and would like your opinion/advice. Ni-Cd Batteries in my old backup drill died and i threw them away. I saw online a couple of ni-cd to Li-ion battery pack conversions. The reason i didn't do it yet is that Li-ion batteries are kind of tricky and i would hate to see them go up in flames.

I do know that laptop batteries aren't heavy duty and i am ok with my cordless drill being less powerfull after the conversion - it being a backup for some easy tasks while my main cordless drill is charging. I was thinking of taking 4 of those batteries and connect them in series to get 14.8V to replace my old 14.4V pack. I would charge the batteries individualy (i have 4 small chargers that charge 1 battery at a time).

Now my main dilema is this: will the fact that those batteries are made for laptops and not for drills mean that cordless drill will simply be less powerfull, or will they overheat and go up in flames ? I am ok with the first thing, the second one, i would like to avoid. I would like it to be as simple as possible but if really necesary, i would include some safeties. I was thinking of some overheat protection (a switch that will turn off when batteries reach a certain temperature, or simply some heatsinks on batteries). I dont think i need low voltage protection since those batteries are old anyway and this is more of a fun project then a long term solution.

So what do you think, can this be done without serious fire hazard ? I love doing projects like this, but the nature of lithium batteries is what worries me.