Sunday, May 12, 2024

Running AC on a Catalina 34 with Batteries

We ran our AC for hours on battery

Working on the boat in May it was HOT!

So we decided to connect shore power at the dock and run the AC, we have a Dometic - ECD10K - Retrofit Kit 410A 115V - MFG NO.207500310. It's located under the V-Berth and has vents in the V-Berth and Main Salon ( ok, so we only have one salon :) )

After connecting Shore power ( 30amp 110V ) and setting the Victron to On, we noticed that the Multiplus 3000 was not running, we tried resetting it but no luck - Hmmmm. Perhaps the issue is with the shore power. I physically disconnected the shore power and reconnected it. Check that the Polarity was correct ( to our knowledge there has been no electrical work on the dock pedestal ) and all was ok. The Multiplus was now working - we're good to go. So I opened the thru hulls for the AC ( inlet and discharge ) and the AC started it's usual start up cycle. We had to move some of the cushions that were covering the cabin air outlet grill ( cushions were from the Aft Berth where we're working on the engine & transmission. ).

Down to work. There was a lot to do as we had only reinstalled the engine a couple of days ago and we needed to reconnect all of the water hoses, coolant hoses, electrical connections, throttle, Gear Change and engine stop cables and install the Alternator.

Just before 3pm both of were beat! Time to go home, finish this job on Monday. That's when I realized that the AC was running off of the Inverter! Not Shore power - Shore power was not even connected! What !!!!!

Seems that the shore power had disconnected ( at the pedestal ) and we had been running the Multiplus, it was inverting the 12v battery power to 110v AC and powering both our outlets which had a couple of battery chargers connected and the Air Conditioning all that time.

Later, at home, I pulled up the Victron VRM and looked at the data.

That shows that the deep discharge of the batteries started at 10:09am 

Note the daily drop in battery SOC is pretty consistent, the only things we have powered when away from the boat at the dock are the Main Bilge Pump ( shouldn't run, bilge is normally dry ) and the Dry Bilge Pump ( Runs for 1 minute every hour even if the bilge is dry ) 

Battery SOC dropped to 20% by the time we turned the AC off. The Inverter was running from 10:35am until 12:39pm just over 4 hours!!!

WOW - We can run the AC during the day for 4 hours if the batteries are at 100% and there is plenty of Solar Power.  This is just what we were hoping for but had not tested it in real world conditions.

Now we need to find out why this happened. I'll check the shore power pedestal and the shore power cable ( we have SmartPlug connection on the boat end of the cable ).

This was a good day.

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