They feed at night, they're designed for it. Difference comes in the food and/or location of it. Daytime food sources basically has a base, phytoplankton's reacting to light and has those above them feeding on and reacting to them. Once the light dies their actions back down, the higher organisms tend to drift towards (if not shut down) other things more easily available usually in a different area. Under water light can get it started in a small area but if the Crappies are elsewhere they may not even notice, care or only drift by occasionally. Need to find where and what they're feeding on at night, be there and exploit it, light or no light. Dawn and dusk catching of any panfish is often related to the plankton turning on or off. Usually a 10-30 minute feeding binge where most any bait can catch most anything. That may be the place to start at night, but be prepared for the night feeding area to be elsewhere, nearby or a ways away