How much carbide do the ships carry for the acetylene lamps? Id imagine if the ship has been subjected to a sufficient blast for an EMP to take out the electronics the lightbulb will be quite dickered and electricity may not be available.
I have an older style "emergency torch". It no longer has any storage capacity (though I expect a couple of minutes with a screwdriver and a fresh set of AA rechargeables will fix that!) but it still functions as an emergency light. So long as I keep working the winder, the small spinning coil next to the small magnet acts as a generator, and basic wire carries that power to an ancient incandescent bulb that only requires electricity to work. That Edison could make such a bulb with the technology available at the time shows it is relatively easy to do.
A small hand-cranked generator, a small 12v lead acid battery as Eltonga mentions, and you're done. So long as the shutters on the lamps still move (they used louvres rather than turning the light on/off), you have an EMP-proof system that can let you communicate over more than shouting distances reliably. So long as the person at the other end can understand the flashes!