Electrical Systems.
When it comes to the electrical system on your boat, at the heart of it are your batteries.
Be aware that the Recreational Craft Directive specifies the installation requirements for both AC and DC electrical systems in small craft. Over the years I have seen many DIY installations which at best do not comply and worst dangerous.
Therefore checkout the regulations are before you undertake any work, and call in a professional if you are in any way unsure.
Batteries.
When it comes to narrowboats you have two battery requirements, taking on two roles.
The first requirement is a standard lead acid starter battery to produce a high peak current to turn the engine over, typically over 1200rpm down to a temperature of -30°C. This is necessary to overcome the mechanical and thermal resistance of the engine in mid winter, and depending on the engine design and standing temperature, requires cranking current up to 1000A.
The vehicle alternator quickly replenishes lost battery capacity when the engine is running.
So never use leisure batteries to start your boat, you will draw too many amps and kill the battery.
The second requirement is the domestic supply, which has to provide a steady flow of current over a prolonged period anmay not get recharged until the user recognises that’s its Voltage level has substantially fallen. At this point, a recharge must be provided. If left for a long period in a discharged state, or left connected to a load which forces the battery into an over discharged state, a battery will not regain its former condition. These conditions can lead to the formation of soft shorts which will render the battery unserviceable.
The average narrowboat needs between 3 and 5 batteries for domestic use, depending on what you use and how much you run your engine and how you charge the batteries.
So for narrowboats the general practice is to market leisure batteries with some indication of the number of cycles that the battery can achieve at 50% state of charge. By design, increasing the number of cycles given by a battery life and durability, rather than start-ability involves extra expense by the manufacturer.
No battery is going to last too long on a boat, It only takes an hours lapse in concentration to fully discharge a battery, and that will impact on its life span. Overcharge any sealed or low maintenance battery and you cannot refill it its as good as dead.
The best batteries for narrowboats are still the deep cycle lead acid battery that you can top up, far more cost effective.
Ok you will have to top up the cells with distilled water every month, but that's a minor issue.
There are many kinds of 'deep cycle battery, Some are branded 'multi purpose' avoid them, these are jumped up car batteries.
In the end it all comes down to weight, pure and simple, the more a battery weighs, the better it usually is. If one 110Ah is 20kg and another 110Ah is 15kg, you will probably find that the 15kg one has 'altered the way it reports its power'. Deep cycle batteries have nice thick lead plates, which weigh a lot.
Lets just look at the different ways of describing a batteries power, deep cycle batteries will give different amounts of power over different times. Over 20 hours a battery may be able to offer up 110 Ah, but if you took it slower, that same battery can give more, 150 Ah over 30 hours. Now some battery manufacturers may give the Amp hour rating over longer time, the standard is 'C20' or how much the battery will give if run flat in 20 hours.
To monitor your batteries you will need a volt meter, ideally you need an accurate digital one, the reason being:
Fully charged 12v lead acid battery is 12.6v.
Fully discharged 12v lead acid battery is 12.0v.
80% charge 12v Lead acid battery is 12.1v.
So accurate measurement is critical.
Personally the best batteries for narrowboats in my mind are still the deep cycle lead acid battery that you can top up.
The first requirement is a standard lead acid starter battery to produce a high peak current to turn the engine over, typically over 1200rpm down to a temperature of -30°C. This is necessary to overcome the mechanical and thermal resistance of the engine in mid winter, and depending on the engine design and standing temperature, requires cranking current up to 1000A.
The vehicle alternator quickly replenishes lost battery capacity when the engine is running.
So never use leisure batteries to start your boat, you will draw too many amps and kill the battery.
The second requirement is the domestic supply, which has to provide a steady flow of current over a prolonged period anmay not get recharged until the user recognises that’s its Voltage level has substantially fallen. At this point, a recharge must be provided. If left for a long period in a discharged state, or left connected to a load which forces the battery into an over discharged state, a battery will not regain its former condition. These conditions can lead to the formation of soft shorts which will render the battery unserviceable.
The average narrowboat needs between 3 and 5 batteries for domestic use, depending on what you use and how much you run your engine and how you charge the batteries.
So for narrowboats the general practice is to market leisure batteries with some indication of the number of cycles that the battery can achieve at 50% state of charge. By design, increasing the number of cycles given by a battery life and durability, rather than start-ability involves extra expense by the manufacturer.
No battery is going to last too long on a boat, It only takes an hours lapse in concentration to fully discharge a battery, and that will impact on its life span. Overcharge any sealed or low maintenance battery and you cannot refill it its as good as dead.
The best batteries for narrowboats are still the deep cycle lead acid battery that you can top up, far more cost effective.
Ok you will have to top up the cells with distilled water every month, but that's a minor issue.
There are many kinds of 'deep cycle battery, Some are branded 'multi purpose' avoid them, these are jumped up car batteries.
In the end it all comes down to weight, pure and simple, the more a battery weighs, the better it usually is. If one 110Ah is 20kg and another 110Ah is 15kg, you will probably find that the 15kg one has 'altered the way it reports its power'. Deep cycle batteries have nice thick lead plates, which weigh a lot.
Lets just look at the different ways of describing a batteries power, deep cycle batteries will give different amounts of power over different times. Over 20 hours a battery may be able to offer up 110 Ah, but if you took it slower, that same battery can give more, 150 Ah over 30 hours. Now some battery manufacturers may give the Amp hour rating over longer time, the standard is 'C20' or how much the battery will give if run flat in 20 hours.
To monitor your batteries you will need a volt meter, ideally you need an accurate digital one, the reason being:
Fully charged 12v lead acid battery is 12.6v.
Fully discharged 12v lead acid battery is 12.0v.
80% charge 12v Lead acid battery is 12.1v.
So accurate measurement is critical.
Personally the best batteries for narrowboats in my mind are still the deep cycle lead acid battery that you can top up.
Inverters.
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Today most people will want and need 240v supply at some point, and this comes from an inverter that converts 12v DC to 240v AC. battery voltage to normal house voltage.
There are two types 'pure sine wave' and 'quasi sine wave', the difference being 'pure sine wave' costs at least three times as much, and won't make your central heating pump hum a little. That's about it. Unless you have some specialist medical equipment on board or a very old TV or Microwave, you wont know the difference, except in bank balance. You can get inverters in all sizes, 150 watts to 5KW. So first things first, if you want to run a 3kw kettle on a boat I suggest you get a generator, same goes for anything over 1kw. Microwave, washing machine, toaster. Your inverter really needs to be for 'usual small power. Inverters are badged 'peak' and 'constant', its simple, if the equipment you need to run is 500w, you need a minimum of 500w 'constant' power. The 'peak' bit is the power the thing needs to start - my TV is 130w, but takes 200w to start, momentarily. The bigger the inverter the bigger the 'quintessential' power, the power to have it sat there producing no usable electricity. When i turn off my TV at night, my inverter uses 0.25amps to keep its brain alive. A 3kw inverter, especially a cheap one is more like 4 amps. And 4 amps is a lot - a 100Ah battery will be dead in 24 hours without having produced any power! Laptops DONT run your laptop from your inverter. Here's why, to turn 12v to 240v you lose 10-15% power minimum, to turn 240v back to 18v as your laptop adaptor does, loses 70+%!!!! in my case 408w in, 65w out so put 1Ah into your laptop battery it takes 9Ah from your boat battery. Buy a car charger for your laptop, and you will get 1Ah for every 1.5Ah from the boat batteries. |
This is a typical inverter specification, advertised as a 6000 watt inverter, beware the continuous rating is actually 1300watts or 1.3 Kw not the 6Kw on the sales advert.
Don't get me wrong, for £55.00 you get a lot of inverter for your money. 
Just remember for every 100 watts of a 12-volt inverter system needs around 10 DC amps from the battery. so at full load the 1300 watt for one hour inverter will use 130 amps from your battery's over the same period.
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If your inverter stops working there are two possible reasons, you connected it the wrong way or its broken.
If you connect an inverter the wrong way, it takes out the PCB fuses. Even if its under warranty, you wont be covered, so you may as well open it up. Do this with the unit disconnected, or you may end up getting an electric shock, be warned.
Inside, if your lucky, there may be a handful of fuses, all blown. Get some and change them. Its worked for me several times.
A broken inverter under warranty should be taken back, one that isn't, should be opened to look at the internal fuses as above.
Also look for loose wires. its more common than you think boats vibrates a lot when engine running.
What kills inverters is, dead shorts ie. crossing the live and neutral 12v wires, putting it in an unventilated area so it cant dissipate heat, putting it in an area that gets damp, getting it wet, using it too hard such as (800w on a 600w inverter constantly)
If you connect an inverter the wrong way, it takes out the PCB fuses. Even if its under warranty, you wont be covered, so you may as well open it up. Do this with the unit disconnected, or you may end up getting an electric shock, be warned.
Inside, if your lucky, there may be a handful of fuses, all blown. Get some and change them. Its worked for me several times.
A broken inverter under warranty should be taken back, one that isn't, should be opened to look at the internal fuses as above.
Also look for loose wires. its more common than you think boats vibrates a lot when engine running.
What kills inverters is, dead shorts ie. crossing the live and neutral 12v wires, putting it in an unventilated area so it cant dissipate heat, putting it in an area that gets damp, getting it wet, using it too hard such as (800w on a 600w inverter constantly)
Solar Panels.
The one and only practical renewable energy source for a boat. I have two 1000w panels on the roof. No special 'sunlight following' devices or any such stuff.
In the summer I don't need to run my engine at all to charge batteries, my domestic usage is covered by the sun! Consider - 14 hours charging at 10 amps is around 140Ah Per day!
As for maintenance, the regular rainfall tends to mean panels stay fairly clean naturally. However as you cruise in some areas you may see a slightly more significant build-up of grime and dust and leaves. There is of course the issue of bird droppings which can reduce output in large amounts if left uncleaned, so its out with the window squeegee and job done.
In the winter the batteries get trickle charged, but its better than that, really cold days means clear skies and weak winter sun, cold means batteries are slow to charge, but solar plugs away at them all morning, and by midday the engine is warm enough to start easily, and the batteries are warm enough from charging to charge properly!
Solar panels are now far cheaper than they were, large panels are still pricey but bargains can be had.
For wiring diagrams go to my Electrical Charging page.
Solar panels always need a solar regulator, These are relatively cheap and easy to wire in, if you don't have one then they will destroy your batteries. Batteries are being constantly charged by your panels, so expect a lot of water usage on your lead acid batteries so remember to keep them topped up.
Also Solar panels will be stolen if not secured. Personally i have grip=filled mine to the roof, as have most of my friends. So far so good.
In the summer I don't need to run my engine at all to charge batteries, my domestic usage is covered by the sun! Consider - 14 hours charging at 10 amps is around 140Ah Per day!
As for maintenance, the regular rainfall tends to mean panels stay fairly clean naturally. However as you cruise in some areas you may see a slightly more significant build-up of grime and dust and leaves. There is of course the issue of bird droppings which can reduce output in large amounts if left uncleaned, so its out with the window squeegee and job done.
In the winter the batteries get trickle charged, but its better than that, really cold days means clear skies and weak winter sun, cold means batteries are slow to charge, but solar plugs away at them all morning, and by midday the engine is warm enough to start easily, and the batteries are warm enough from charging to charge properly!
Solar panels are now far cheaper than they were, large panels are still pricey but bargains can be had.
For wiring diagrams go to my Electrical Charging page.
Solar panels always need a solar regulator, These are relatively cheap and easy to wire in, if you don't have one then they will destroy your batteries. Batteries are being constantly charged by your panels, so expect a lot of water usage on your lead acid batteries so remember to keep them topped up.
Also Solar panels will be stolen if not secured. Personally i have grip=filled mine to the roof, as have most of my friends. So far so good.
Generator.
There is no excuse for using a generator regularly, It will annoy other boaters, local residents and towpath users.
It is acceptable to use a generator for running a washing machine a few times a week, or a power tools that's too big for your inverter, but using one to run your TV at night is not ok.
Also If you do regularly run a generator, your advertising to thieves, (a generator is easy to sell quickly) This is compounded by the fact that If any boats are still moored near you and haven't moved because of the noise, they will have
1) Closed all doors and windows directed your way because of the noise
2) Be quite pleased if someone runs off with your generator.
If you must have that much power, consider having a 240v alternator installed or a marine generator in your engine bay. A boat engine has a far nicer sound than a frantic little generator.
It is acceptable to use a generator for running a washing machine a few times a week, or a power tools that's too big for your inverter, but using one to run your TV at night is not ok.
Also If you do regularly run a generator, your advertising to thieves, (a generator is easy to sell quickly) This is compounded by the fact that If any boats are still moored near you and haven't moved because of the noise, they will have
1) Closed all doors and windows directed your way because of the noise
2) Be quite pleased if someone runs off with your generator.
If you must have that much power, consider having a 240v alternator installed or a marine generator in your engine bay. A boat engine has a far nicer sound than a frantic little generator.
