Try restricting the battery movement, most real weapon lights have a shoulder in the battery tube anode side to keep the battery from impacting the spring/driver, protecting both driver and cell(s) maybe use o-rings to restrict movement. I also added extra shrink wraps to batteries that have oversize battery tubes, so they just slide in, now I size the inside of the battery tube and polish to fit specially in my 2S tubes. Just my 2cents.