I’m just getting into battery builds & for my first build I tried to replace a Porter Cable drill battery. It has a dozen sub C batteries in the pack. I put together in series 4 3.7 18650 batteries. The drill runs but seems slower than it was using the pack that it came with. Please let me know what I did wrong or what I should of done. I’m kind of excited about my new hobby it seems everything needs batteries.
Thank you,
Fred