HMV Barn Project

[Refugee]

If you want to see how easy it had been for you to get to components look away from post #48 in this thread.
http://golbornevintageradio.co.uk/forum/...p?tid=4959&page=5

[Nowhere-Man]

You will all need to bear with me a bit as I'm presently re-wiring my boat. I'll do radio work again when it gets rainy. I'm still stunned that the former electrician cabled in an inverter/charger in such a way as I had to dismantle the entire system to get at one 15 Amp fuse. This was located at the rear of the inverter/charger and turned out to be shot. All I need is a new 15 amp fuse and the inverter ought to work and charge my batteries.

The inverter had been squeezed into a small cupboard and then battery cables pulled rigid to the rotary selector switch in the engine bay. To free it I had to dismantle lots of cable (300 mm at that).

For some reason, shore power had been directed to the inverter/charger prior to the consumer unit. This simply meant a 15 amp fuse, crammed out of sight and reach being the weak link that could cripple the entire supply. Normally it should be a simple MCB to put power back on.

The best marine engineer I know is John C Payne and his book on marine electrical and electronics is well worth a read. I'll be using his approach on my rewire.

[Crackle]

All I need is a new 15 amp fuse and the inverter ought to work and charge my batteries.

I wonder why the 15 amp fuse blew, it maybe worth a careful investigation.

You must have some means of isolating the mains "shore power" when the boats 240v AC sockets are being supplied by the inverter. As it is a Charger/inverter it may have an automatic changeover switch built in.
In which case it makes sense to take the rest of the boats mains wiring from the change over switch.

I would find out the make and model of the charger/inverter, get hold of the installation instructions and follow the wiring instructions for that specific device.
I have rewired a few boats I have owned including my first boat, a Colvic motorsailor which I built in the 1980's from the bare mouldings.
Mike

[Nowhere-Man]

All I need is a new 15 amp fuse and the inverter ought to work and charge my batteries.

I wonder why the 15 amp fuse blew, it maybe worth a careful investigation.

You must have some means of isolating the mains "shore power" when the boats 240v AC sockets are being supplied by the inverter. As it is a Charger/inverter it may have an automatic changeover switch built in.
In which case it makes sense to take the rest of the boats mains wiring from the change over switch.

I would find out the make and model of the charger/inverter, get hold of the installation instructions and follow the wiring instructions for that specific device.
I have rewired a few boats I have owned including my first boat, a Colvic motorsailor which I built in the 1980's from the bare mouldings.
Mike

I'd say the inverter is a nineties device. It draws about 6 amps off-load. It was made in Taiwan and, yes, I have the booklet. The manual makes it very simple and shows the inverter/charger simply plugged into mains as you would any car battery charger. Two heavy duty leads run to the batteries and charge by trickle or fast charge. Should you not have a mains supply (Power cut), you can switch the inverter itself on and it will then supply 250 AC just from the car batteries.

I'm really not sure why the shore supply was fed directly to the inverter. This must have been the case because when the fuse blew, that totally cut off my supply. I had no shoreline or anything. So, I removed the existing cables to the consumer RCD, fitted a new one with arctic cable and then ran the other end of that to the shoreline socket. That restored power. Direct connection to supply.

I now have removed the inverter but to do that I had to dismantle lots of cable. It had to be removed from the battery selector switch to free up enough play to draw the unit out of a cupboard. The fuse was a 15 amp one in a small socket at the back. It was blown out.

I have no DC at the moment as I plan on redoing the whole lot. I just bought fuses and will test the inverter tomorrow and see if it works.

I'm not going to be too critical of the sparky who wired this up but, based on experience, I'd recommend easy access to inverters and I wouldn't let my entire supply depend upon one 15 amp fuse. Maybe you'd expect the RCD to have tripped first but, for whatever reason it didn't. The fuse did but access involved a lot of dismantling as it was cabled into a cupboard very tightly. Had the MCB tripped, it would have been simple.

[Terry]

... Should you not have a mains supply (Power cut), you can switch the inverter itself on and it will then supply 250 AC just from the car batteries ...

Car batteries? Why on earth would you use car batteries?

Car batteries are designed with one prime purpose - to provide a heavy current for a short time to start the car engine. After that, the load is taken up, in the main, by the alternator which also recharges the car battery at the same time.

What you need are so-called leisure batteries which are designed to provide power at a much lower rate than required for starting a car but to do so for long periods of time.

[Crackle]

I think you need to think very carefully about how you are going to wire the shore power, charger, and inverter. Particularly if you are going to connect up the inverter to the SAME sockets normally used for the shore power. You need a fool proof method of isolating the shore power and the inverter from each other. Is it possible that is what the switch on the inverter did. I would advise asking a professional marine electrician.

Mike

[Ed_Dinning]

Hi I'd second the remark about car batteries; they may be cheap but have entirely the wrong characteristic to power an inverter. Leisure batteries as supplied to motor homes are what is required. A separate starter battery should be used for starting the engine, charged by the alternator.
If you get an electronic charge splitter (not just 2 diodes), it is possible to charge starter and housekeeping batteries when moving. It can also be arranged to charge at a higher rate when the engine is idling if an external control box is added to the alternator (or you can use 2, with a longer drive belt.

Be careful what you run from your invertor as it may not give a sine wave output and may damage some AC equipment.

Your Payne book sounds very useful, but you may find things have moved on since it was published. It should be simple enough to fit MCB's as you sound to be doing a major re-wire and some automatic change over equipment. Do not use AC contactors on DC. Albright do an excellent range that are used on electric vehicles.
The 17th edition of the IEE wiring regs has some detail that will be pertinent; it is not specific to canal boats but covers both transport and marinas.

Ed

[Refugee]

There is basically two AC power supplies and something must be fitted that prevents both from being connected at the same time.
There are two switching functions that must not take place at the same time and must take place in the correct sequence.

[Nowhere-Man]

... Should you not have a mains supply (Power cut), you can switch the inverter itself on and it will then supply 250 AC just from the car batteries ...

Car batteries? Why on earth would you use car batteries?

Car batteries are designed with one prime purpose - to provide a heavy current for a short time to start the car engine. After that, the load is taken up, in the main, by the alternator which also recharges the car battery at the same time.

What you need are so-called leisure batteries which are designed to provide power at a much lower rate than required for starting a car but to do so for long periods of time.

I'm afraid you jumped the gun a bit here by taking me so literally. By "car batteries" I simply meant "lead acid batteries".

Basically anyone who owns a yacht or narrow boat is going to know the difference between leisure and starter batteries. At least I hope they do.

Starter batteries as you say are designed for starting an engine. These are special batteries that are rated in CCA (Cold Cranking Amps). The system used in the eighties when things were a lot simpler was as follows:

2 or 3 House batteries that (if my memory serves me correctly) can supply about 300 Amp Hours.

Starter battery connected to system by a split charge relay. On turning ignition the alternator B+ supplies about 14 volts to all batteries but (when ignition is off), the starter battery is disconnected from the House supply. Actually I need to buy one of these. There is also the diode isolation system to prevent drawing from the starter battery but this does cause a small voltage drop in charging. I'm not sure how much a diode isolator is but I'm sure the fancy regulator you need for upgrade is still not cheap. So, I may settle for just a relay. I was looking into current ratings and automotive types aren't really suited (although people use them).

As to the way and means of coupling shoreline and inverters, I do know it's important not to mix outputs. I'm not yet sure how I plan to make a system but imagine I may be converting to solar power.

At the moment, I have replaced the inverter/charger with a 15 amp fuse and have it charging up a clapped out battery that had dropped to 9.5 volts. I put a plug on the inverter as it's shown in the booklet and just plugged it in. So, the inverter is secondary and used as an appliance. The battery is reluctant to charge. It may or may not have sulphated but sometimes it's possible to get a charge. Time will tell. I have to step over it as it's on the floor at the moment charging.

One thing I discovered was I think it's a ferro resonant charger because the booklet shows a max current of 10 amps at charge yet lower voltage. When the voltage goes up to 13, current drops. There was a debate with a friend about cable size but I ended up fitting a very high amps cable, mainly to accommodate any surge or high load across the inverter.

This is a modified sine wave unit. Not sure how my radio would work on it.

[Nowhere-Man]

Hi I'd second the remark about car batteries; they may be cheap but have entirely the wrong characteristic to power an inverter. Leisure batteries as supplied to motor homes are what is required. A separate starter battery should be used for starting the engine, charged by the alternator.
If you get an electronic charge splitter (not just 2 diodes), it is possible to charge starter and housekeeping batteries when moving. It can also be arranged to charge at a higher rate when the engine is idling if an external control box is added to the alternator (or you can use 2, with a longer drive belt.

Be careful what you run from your invertor as it may not give a sine wave output and may damage some AC equipment.

Your Payne book sounds very useful, but you may find things have moved on since it was published. It should be  simple enough to fit MCB's as you sound to be doing a major re-wire and some automatic change over equipment. Do not use AC contactors on DC. Albright do an excellent range that are used on electric vehicles.
The 17th edition of the IEE wiring regs has some detail that will be pertinent; it is not specific to canal boats but covers both transport and marinas.

Ed

John C Payne's website is here:

http://www.fishingandboats.com

I found him to be exceptionally good. His philosophy of making simple and direct electrical systems is the way to go. I've seen far too many over-complicated systems that have let people down (as I was let down when my inverter crashed).

His book the Electrical And Electronics Bible is a must-read. It contains a whole chapter just on batteries. Then another chapter on alternators and even how to change regulators or fit smart regulators. Engine wiring and D.C. systems plus all cable ratings are in another chapter. The back has information on just electronics such as Radar systems and HAM Radio. I have the eighties publication but I don't mind as I like the simpler systems that were used in the eighties (and had to laugh at reference to VCR).

The amusing part is a comment at the end to boat owners who call out marine service technicians to yachts. "Asking the engineer if 'he's fixed it yet' or 'found the problem' may lead to sharp exchanges if the engineer is in some tightly cramped compartment.