Solar Battery Charging

My roof air conditioner has a solar charger that connects to the rear battery. The connection (one wire only) is on the negative post of the battery. Is this correct? It is a new battery and it went dead.
Mario, (San Leandro, CA)

Mario, the simplest of DC circuits mandates that a minimum of two wires be present; the charge line (positive 12-volts) and a return path to ground. It appears there is a hot wire missing from the solar panel mounted on the roof A/C. The solar panel can still generate a charge, but without that wire to the positive side of the battery, an open circuit exists and no charging is possible. Remove the solar panel and see if the missing wire either broke away from the panel or was never routed to the battery. It may be possible to rewire the panel and run a new charge line to the positive post of the battery, but a close inspection must be made first. Plus the panel itself should be tested to be sure it is still functioning properly.