This work light...
[Link: m.harborfreight.com]

Plus this battery charger...
[Link: amazon.com]

Plus...
the 18650 cells from your old laptop battery

Equals a whole lot of light.

I have only been to Harbor Freight three times. This third time I found this worklight and love it. It has a magnet, so I can attach to the metal on the submarine. And the bottom unscrews so I can swap out the 18650 for a charger one. Which I happen to have 6 from my old laptop.

KOT