Salt chlorine generator.

Hello everyone this is my first post. I have an 18,000 gallon salt water pool with an AqualCal digital nano+ salt chlorine generator. I had been getting an error message for Low Volts. I recently had my local pool company come look at it(they are Also the ones who did install). The man checked cables and salt cell and everything appeared to be fine
He did adjust the chlorine %, and also mentioned one of the wires was loose. When he left my volts were back up to 18V. The following day the same error message was back. I since went down to pool store to chat. Gentlemen who also has salt pool said it could be due to cold water temp(at time it was around 68 degrees). He advised me to continue shocking water until it warmws up. The pool reached 72 today and I still received Low Volts. Anyone have any knowledge of this problem? Do I need to let pool warm up more? I hope this is not a trend with these salt systems. Any knowledge would be much appreciated. That ks