Sort of. Wait until the batteries get low, connect it, and *disconnect it again* when the voltage passes about 14.2-14.4 or so.
I had to do this flying once. The alternator wiring had a short to ground that drove the regulator to full output. The overvoltage warning went off, we truend the alternator off, and when the battery got low we turned it on for a bit. Managed to keep the lights on until we landed (this was after dark