Lagoon 380 Lithium Project

More Solar and Batteries = Noise and Pollution Free Air Conditioning

Air Conditioning off Batteries

The Lagoon 380 is a 38 ft Catamaran with 21 ½ ft beam and a very popular cruiser around the World.

This Lagoon previously had a generator to provide electrical power for Air Conditioning at anchor and away from shore power.

The Cat has 2 Air Conditioning units; a 16 and 12 BTU Cruise air. 

Expectations and Goals of the Lithium Project

This Owner wanted to be on the hook and run Air Conditioning without a generator with its associated noise, fumes and fuel needs. 

Air Conditioning off Batteries

Running Air Conditioning generally requires a shore power connection or Generator to handle loads. 

However within the last year or so the increase in energy density of the latest Lithium batteries and the advanced equipment to manage and distribute power, it is now possible to rely on Solar and Battery storage to replace the need for a Generator. At this point Catamarans have the deck space to install enough Solar to facilitate this feature .

The Lagoon has a hard top above the steering station that is perfect for solar panels. An additional arch was added to increase the Solar Panels to 1580 watts. The new arch had 3 x 360 watt panels in addition to the 500 already on the hard top.  

The 1200AH battery bank was situated under the aft port berth.

Designing the system

After the brief from The Owners, Chris Humphries from Annapolis Yacht Sales collaborated with Peter at PKYS to come up with a plan to achieve the Owners Goals. Below is the Final Diagram of the Electrical System. A list of components are below.

The system accepts power from Solar, Shore Power, Engine alternator and Batteries. The Features of the Quattro inverter will take power from whichever sources are available and distribute them accordingly. 

One advantage of Lithium batteries is that due to their low internal resistance they will accept a very high rate of charge and so will charge quicker than Lead Acid. This means even in short periods of motoring the batteries can quickly get a charge.


Victron Lithium batts 300AH X 4 for 1200 AH stored under port berth      

Quattro 12/5000/220 Inverter Charger 120 Volt AC, 12 Volt DC   

Solar Panels;  3 x 360 and original 500 watts  for total 1580 watts         

MPPT charge controllers      

Cerbo & Touch 50     Cerbo is the main control of the system       

VE bus BMS              the BMS is needed for Lithium batteries

Smart shunt   this shunt is a Battery monitor which uses your phone/touch50 to read the data

Battery Protect this protects the batteries in case of a system failure.

Digital Multi control  adjust charge current on the fly when connected to shore power

DC DC charger  one for each engine 

The port aft cabin provides lots of space for the Batteries and equipment.

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