SV Unladen Swallow's AC (Alternating Current) Electrical System - 110 VAC
Introduction of AC power on boats.
When you mention electrical power, most people immediately think about the power they use at home - for Americans, this is 110 VAC. That's Alternating Current that is configured to 11o Volts.
This is what our normal household appliances work off of and what we get when we plug into a standard US Electrical Outlet. This power is generally produced at a power generation station and is delivered to your house by a combination of overhead and in some cases buried lines.
On a boat, this power is provided by either a Generator (GenSet) that outputs 110VAC or from a DC to AC Inverter that converts battery (Direct Current) to Alternating current. This allows us to use the microwave, coffee pot and watch TV.
When we bought the boat, the GenSet was working (kind of) and it had a Inverter capable of producing 3000W of 110 VAC. There was also an outlet on the back of the boat that you could plug an extension cable into (think RV Electrical Cable) to draw 110VAC from shore power.
**** Disclaimer **** We are not Marine Electrical Engineers - we are not certified and anything we describe here is not intended to be used as reference material for your own work. Please do your own home work and better yet hire someone who does this for a living!
AC Electrical System 2021
When we bought the boat we found what was likely the original 110VAC electrical panel that had 4 circuits for the boat – 2 that ran off the inverter (Outlets) and 2 that were GenSet/Shore Power only (Hot Water Heater & Air Conditioner, we later learned that the Water Maker power bypassed this panel)
In early work that we did, after switching off batteries and turning off breakers, we were still finding hot circuits. This was cause for concern and I really wanted to get to the bottom of why there was still power after shutting everything off.
We knew we needed to add the Scuba Compressor and likely some other things from a boat automation perspective so while we were working on the DC system, we chose to also redo the AC panel.
We had this panel custom made by Blue Sea Systems with the help of PKYS. It’s setup with a Shore Power/ Genset lockout switch on the left with a multimeter below. The center column is for the circuits that will be powered only when the GenSet or we are connected to Shore power. At the top is a breaker that controls AC power going to the inverter/charger. On the right hand side are the circuits that are powered by the Inverter. There is also a breaker at the top that is the master input from the inverter. All AC power on the boat now flows through this panel.
NOTE: during the 2022 lithium upgrade we moved some circuits from the non-inverted to the inverted side and added several circuits to this panel.
As an interesting side comment, we finally traced the source of the always on power to the battery that was powering the windless at the front of the boat – it was back feeding the old inverter and allowing it to stay on even though it was disconnected from the house batteries and any shore power sources.
The major Reconfiguration in 2022
The GenSet is removed - it was too small for the Scuba Compressor and was duplicative to the new Balmar Alternator.
Next we removed the old Zantrex 3000W Inverter/Charger and replaced it with Lithium Aware Victron 5000W Multiplus. We now have sufficient AC power for anything (except apparently our power hungry Scuba Compressor)