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Posted: Fri Jan 01, 2016 1:19am

Post Subject: Generators

Hi I'm in the process of buying a Narrowboat as a live aboard. I've decided to go down the route of having a diesel generator fitted.can you advise me of a type that would fit on the top of the swim in the engine bay of a cruiser stern. I'm thinking of around 4kw professionally installed cocooned type. Also I'm going to install solar panels. What electrical equipment such as battery charger, battery management systems would i need to have to get the most out of the solar panels, batteries etc. Tony


Posted: Fri Jan 01, 2016 8:15am

Post Subject: Generators

I can not give advice on particular makes of anything. Your generator needs to be small enough to fit on the swim and under the deck boards. I am sure your installer will have a favourite make and model but if you are given a choice of makes take a look at the cost of spare parts. If you are contemplating a petrol generator my advice is simply "forget it". Petrol on boats complicates things as far as the Boat Safety Scheme is concerned. The solar panels will require their own charge controller and an MPPT type is the most efficient at maximising the battery charge from the panels. A 4 Kw generator will drive almost any sized battery charger but a multi-stage one designed for marine use so it can not overcharge the batteries, is designed to be left running for long periods and is moisture resistant. If this were to be shore line powered a very modest one of 10 of 20 amps would be fine because it could be left on 24/7 but the generator complicates things because that is unlikely to be running for many hours at a time. The optimum size depends upon your battery bank size AND electrical demand to a degree but I suspect something around 30 to 40 amps would be fine. Again your installer should be able to give better advice once they have questioned you and sized up the job. I note that you make no mention of an inverter to provide 240V AC when you are away from a shoreline and the generator is not running. I assume that you already have one. If not be aware that you can buy combi-units that are battery charger and inverter all in one. Some may also have provision for controlling solar charging BUT if one part of such units fail you loose all the other functions. I favour separate units. Please do a power audit and charging calculations to ensure that your battery bank is large enough for your needs and can be recharged within the time limits (8am to 8pm) CRT allow for engine running without moving - this includes generator use. Ideally you will have a means of monitoring the state of battery charge. The simplest is a product known as a Smartgauge. I use ammeter and voltmeter readings at various times of the day but that needs knowledge and experience to get right. Most other battery charge meters have the tendency to drift out of true over time unless you very regularly get the batteries to all but 100% of fully charged and they 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. Most also give and amps and volts read out so those can be used by an experienced person to estimate battery charge. There are entrenched views about the effectiveness of both types of meter but for an inexperienced boater I feel the Smartguage probably has the edge.

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