1988 Southwind Electric Control Center

Reconnecting battery cables after winter storage (1988 Fleetwood Southwind). Where do I connect the white wire running from the electrical control center under the hood? This wire runs from a bus bar in the center of the panel (with many other white wires) to the battery area. It's been connected before, I just forgot to label it when I removed it last fall. Suspect ground, since all fused (+) wires are non-white (-). Want to be 100% sure though.

Thanks