Inverter Installation and Battery Relocation


I purchased a Promariner 2500 alternator that was capable of supporting occasional loads such as morning coffee and appliance battery charging without running the generator. While the unit was not capable of supporting the built in 16,000 Btu/hr air conditioner, it would support a smaller unit that might meet nearly all of our South Florida cooling needs when running the main engine underway.

ProMariner 2500 under V Berth

The New Inverter is mounted under the forward bunk in a dry and otherwise unused space. It is powered directly off a battery that is part of the house bank using very short cables.

Controlling the inverter is a challenge. The normal method is to place it in the path from the shore power inlet to the circuit breaker panel. That way, when shore power is disconnected, the inverter automatically picks up the load. We did not want this because shore power is often unreliable and should it fail in the middle of a hot night, we were concerned the inverter would kill the batteries trying to cool the boat.

We wanted a little more power management. The standard Mace 2.5 KW generator will operate the air conditioner and one burner of the stove while charging the batteries and still have a little extra power. The shore power cable will do all that and run the microwave without exceeding the 30 amp (3.6 KW) supply in most marinas.

This means that everything will run on shore power, lots of stuff will run on the Mace Generator and only the small air conditioner will run on the inverter. I wanted to make it easy to run the correct stuff at the right time.

Here is the original AC distribution panel after I added the new Inverter control. The new control is just above the engine waste heater knob on the right.

The sub-control on the left controls the source of power to the boat. The top left switch connects the shore power cable to the bus.

The top double switch shows two indicators, the green light indicates the shore power source is selected and available. Below that is a red indicator, indicating a short circuit within the boat or the shore power supply.  If this light is lit, the boat should be immediately unplugged from shore power and the source of the short circuit investigated.

The second double switch is labeled “Generator” and now controls both the generator and the new inverter. As with the top switch, the green lamp is lit when internal power device (inverter or generator) is producing power for the boat. Also, as with the top indicator, there is a red light that indicates an internal short in the generator inverter when lit.  If this lamp is lit, both the generator and inverter should be turned off.

In most cases, the red lights will be lit only when first turning on the shore power, generator, or inverter. Once the system is operating normally, should a fault be detected, the respective circuit breaker will automatically trip or shut off.

There is a locking mechanism that keeps the shore power and internal inverter or generator power from being on at the same time. This mechanism easily slides up and down when both switches are off. Slide it to the desired position to permit either the shore power or generator power switch to be turned on.

The meter located above the switches shows the voltage present in the boat. Normally this is 120 volts, but it can vary 10 or so volts either way without a problem. This meter may dip briefly when the air conditioner starts.

On  the right side of the panel are the “LOAD” switches. When operating on shore power. any switches you need may be turned on. I suggest normally keeping the stove and water heater turned OFF, operating them only as needed.

The stove and water heater can not both be used on generator at the same time and neither can be used on the inverter.

The air conditioner switch operates the  larger boat air conditioner. The boat air conditioner will operate on shore power or the generator but not the inverter.

The busted switch second from the bottom operates the new roof air conditioner. It normally is on and takes no adjustment. A replacement switch is on order.

The inverter has a new control located just above the AC distribution panel next to the helm seat. Position 1, the top position, is selected when the generator is desired.  Start the generator, allow it to warm up, Select “Generator” on the AC distribution panel, and place the inverter control in “Shore Power/Charge.” The inverter will automatically supply power whenever the generator is not running and charge the inverter battery when the generator is running.

The middle position, “OFF” delivers no power, even when the generator is running.

To use the inverter alone, select “Generator” on the AC distribution panel and place the inverter control in the “II” position. “Inverter”.

Since the new air conditioner is mounted overhead, a temporary switch was installed just aft of the starboard forward window, just over the sink. This switch is effective with either the shore power, the generator, or the inverter.

I hope this is less confusing to you than it is to me.