What type of generator for a liveaboard?
QI’m looking to fit a 4kW professionally installed cocooned type diesel generator in my liveaboard boat. What type would fit on the top of a cruiser stern swim? I am also going to install solar panels. What battery charger, battery management systems etc would I need to get the most out of the solar panels and batteries?
We don’t usually give advice on particular makes, but it would need to be small enough to fit on the swim and under the deck boards. If your installer offers you a choice, look at the cost of spare parts.
The solar panels will require their own charge controller and an MPPT type is the most efficient at maximising charge.
A 4kW generator will drive almost any sized battery charger, but the ideal type would be a marine multi-stage charger designed so that it cannot overcharge the batteries, can be left running for long periods and is moisture-resistant.
If shoreline-powered, a modest 10 to 20 amps would be fine because it could be left on 24/7; the generator complicates things because it is unlikely to be running for many hours at a time. The optimum size depends on the battery bank size and electrical demand, but something around 30 to 40 amps should be fine. Again your installer should be able to advise.
Do you have an inverter to provide 240v AC away from a shoreline when the generator is not running? If not, you can buy combi-units (pictured, left) that combine charger and inverter – and possibly provision for solar charging control too. On the downside, if one part of such units fails you might lose all functions.
Do a power audit and charging calculations to ensure your battery bank is large enough and can be recharged within the time limits ( 8am to 8pm) CRT allows for engine running (including generators) while stationary.
Ideally, you will have a means of monitoring the battery charge: the simplest is a Smartgauge. Other charge meters can drift out of true over time, unless you very regularly get the batteries to very nearly fully charged, and can tell you the batteries are far better charged than they really are. Such meters need setting up properly and regularly re-synchronising with the battery banks’ ever-decreasing capacity. As they display amps and volts, an experienced person can estimate the battery charge.
There are entrenched views about the different types of meter but, for an inexperienced boater, I feel the Smartgauge probably has the edge.