General power arrangements - slightly disappointing

Sea-Fever

Sea-Fever

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Being relatively new to boating, and if I'm being honest...

I'm a little disappointed with the general arrangements for power on my second hand boat. I didn't really look into it at the purchase stage but it wouldn't have prevented me from buying it.

It is 40 yrs old as we'll so maybe I was asking alot.....but.....

In my head small boat electrics worked like this:

1. 12v system runs off batteries...which are charged by an alternator
2. When available plug in the shore power which achieves the following;
A) Provides 240v through mains sockets
B) Powers the 12v system
C) Charges and maintains the 12v batteries

All of the above without having to detach batteries, mess with crocodile clips etc

Is this a common arrangement or one which I can retrofit?

Do others have similar arrangements and, if so, what are the main components?

Only a brief overview of components required, thanks for any help.
 
you will get a million knowlegable and potentially expensive answers. Fundamentally it is as you state, and then people add more or less complication/automation.
To get you basically sorted, you have an alternator on the engine to charge the battery.
If you want 240 shore power you can just purchase an rcd unit and cable from a camping shop , that will give you a couple of plug sockets, and will store in a locker when you dont need it.
With that you have the facility to use power tools etc on board, so you can set about doing more work on wiring if you wish.
Lots of people on here have some very well sorted and complicated set ups, with intelligent split charging, solar, wind etc.
But start simple, and see what you actually need.
 
solent clown said:
you will get a million knowlegable and potentially expensive answers. Fundamentally it is as you state, and then people add more or less complication/automation.
To get you basically sorted, you have an alternator on the engine to charge the battery.
If you want 240 shore power you can just purchase an rcd unit and cable from a camping shop , that will give you a couple of plug sockets, and will store in a locker when you dont need it.
With that you have the facility to use power tools etc on board, so you can set about doing more work on wiring if you wish.
Lots of people on here have some very well sorted and complicated set ups, with intelligent split charging, solar, wind etc.
But start simple, and see what you actually need.
Click to expand...

Sorry I should make clear -

I already have separate 12v and shore power but they are just that....separate!

If I want to charge the batteries...I have to detach them and use a mains charger with crocodile clips. Also the shore power doesn't power the 12v systems. Seems like a lost opportunity!
 
Bit confused. You have mains power so you could simply plug a cheap car battery charger into the mains power and attach charging leads from that to your batteries in situ using croc clips. basic charging accomplished ! You would then go on to buy and fit a more powerful and intelligent charger and fit that properly to the batteries.
Then as solent clown suggests it is just a case of refining your system using ( or ignoring as appropriate) helpful tips from the forum.
 
Puzzles me, why you want to disconnect the batteries while charging them. Entirely unnecessary. I have a smart charger permanently connected to my battery bank. As soon as plug my 240V system in the shore power, the charger kicks in. Being "smart", it automatically compensates for any load I put on the 12V system - you can actually consider the 12V appliances being run from the charger. As for the 240V system, I normally feed it from a 3.5 kW inverter (I have 1,500 Ah deep cycle batteries) so I can run virtually any normal household appliances from it. As soon as I plug into shore power, the inverter automatically disconnects and I am running all from the grid.
The system is not as complicated as it may seem, but there are some traps and I would discourage you from trying to do it yourself unless you are a qualified electrician (I am) for safety reasons.
 
Sea-Fever said:
Sorry I should make clear -

I already have separate 12v and shore power but they are just that....separate!

If I want to charge the batteries...I have to detach them and use a mains charger with crocodile clips. Also the shore power doesn't power the 12v systems. Seems like a lost opportunity!
Click to expand...

shore power provides battery charging which effectively allows you to use your 12v system anyway. You can always add a 12dc power supply too if you want to stay 12v.
People will be along in a mo to tell you how it is all done properly in the fabulous way they do on here. It is one of the most amusing subjects for me, the low tech of sail power mixed with some of the complicated electronics some people fit. I love how many different approaches there are, so be prepared for a deluge of suggestions and ideas, you will just have to pick what suits you best.
Would help the experts if you outlined your needs a bit more, and size of boat, what engine etc. Whatever you do DO NOT mention 1 2 both switches :rolleyes:
 
a boat I bought yesterday and am delighted with has for its main electric cut offs, two ancient bakelite switches, and the bilge pump switches off an old domestic light switch. It's all so charming I might just leave it in.
 
Sea-Fever said:
the shore power doesn't power the 12v systems.
Click to expand...

The 12 V circuits are powered by the batteries . The shore power alone does not usually provide 12 V power. In other words you do not usually have 12V power with the batteries disconnected.

However it is usual to have a fitted battery charger that can be switched on when on shore power.
A suitable fitted charger may be a Sterling charger .
https://www.mdsbattery.co.uk/sterling_chargers.html

.
 
Sea-Fever said:
In my head small boat electrics worked like this:

1. 12v system runs off batteries...which are charged by an alternator
2. When available plug in the shore power which achieves the following;
A) Provides 240v through mains sockets
B) Powers the 12v system
C) Charges and maintains the 12v batteries

All of the above without having to detach batteries, mess with crocodile clips etc

Is this a common arrangement or one which I can retrofit?.
Click to expand...

That's how it should be and you can retrofit.

But, you don't give enough information.

  • What boat do you have ?
  • What equipment do you need to power ?
  • What batteries do you have ?
  • What charger do you have ?
  • Budget ?
 
MartynG said:
The 12 V circuits are powered by the batteries . The shore power alone does not usually provide 12 V power. In other words you do not usually have 12V power with the batteries disconnected.

However it is usual to have a fitted battery charger that can be switched on when on shore power.
A suitable fitted charger may be a Sterling charger .
https://www.mdsbattery.co.uk/sterling_chargers.html

.
Click to expand...

Most decent, modern chargers will run the boat, with or without batteries. The Sterling ones you linked to will, as will most of the Victron chargers, Mastervolt chargers etc.
 
PaulRainbow said:
Most decent, modern chargers will run the boat, with or without batteries. The Sterling ones you linked to will, as will most of the Victron chargers, Mastervolt chargers etc.
Click to expand...

I don't understand how any charger is meant to 'know' what state the battery is in if there are various loads being switched on and off whilst I am on board and perhaps even when I'm not onboard if i wantet to keep some bits and bobs on....does this not affect the charging regime?
 
Plus....how does it work with more than one battery in a bank?

Hence the initial questions re general arrangements for power on a boat.

For info its a 33ft sailboat with the usual instruments, plotter, vhf, bilge pump, lights, fridge, electric windlass.

Currently two batteries in a bank with a 1 2 BOTH switch (hahahaha)

There is also shore power from the 70's which I will need to change for a RCBO or whatever....I'll pay for someone to do that I should think.....
 
Sea-Fever said:
Plus....how does it work with more than one battery in a bank?

Hence the initial questions re general arrangements for power on a boat.

For info its a 33ft sailboat with the usual instruments, plotter, vhf, bilge pump, lights, fridge, electric windlass.

Currently two batteries in a bank with a 1 2 BOTH switch (hahahaha)

There is also shore power from the 70's which I will need to change for a RCBO or whatever....I'll pay for someone to do that I should think.....
Click to expand...

Once you start to get quotes you may well see why the boat has the system it has. I would like an all singing system on my boat but when I look at the cost I decide to stick with bits that I plug in as and when required. The one that I have done though is install 240 volt sockets though a double pole RCD, circuit breaker, etc.
 
jiris said:
Puzzles me, why you want to disconnect the batteries while charging them. Entirely unnecessary. I have a smart charger permanently connected to my battery bank. As soon as plug my 240V system in the shore power, the charger kicks in. Being "smart", it automatically compensates for any load I put on the 12V system - you can actually consider the 12V appliances being run from the charger. As for the 240V system, I normally feed it from a 3.5 kW inverter (I have 1,500 Ah deep cycle batteries) so I can run virtually any normal household appliances from it. As soon as I plug into shore power, the inverter automatically disconnects and I am running all from the grid.
The system is not as complicated as it may seem, but there are some traps and I would discourage you from trying to do it yourself unless you are a qualified electrician (I am) for safety reasons.
Click to expand...

I didn't appreciate that a smart charger is not affected by additional load whilst charging, in which case there is no need to isolate the batteries from the 12v system when charging.

Not sure about an inverter with such a small battery bank.....not with my wife's hairdryer in her holdall!!

So I have 2 x 110ah batteries.....what charger would you (anyone) recommend. I can't see a situation where I want to operate the windlass on shore power but definitely the fridge...most other things are small fry.
 
Last edited:
Sea-Fever said:
I didn't appreciate that a smart charger is not affected by additional load whilst charging, in which case there is no need to isolate the batteries from the 12v system when charging.
Click to expand...

No need whatsoever.

Not sure about an inverter with such a small battery bank.....not with my wife's hairdryer in her holdall!!
Click to expand...

An inverter would be a bad idea for your setup.

So I have 2 x 110ah batteries.....what charger would you (anyone) recommend. I can't see a situation where I want to operate the windlass on shore power but definitely the fridge...most other things are small fry.
Click to expand...

I'd suggest a Victron charger, with outputs for both banks. This will keep all batteries charged and will act as a power pack to run stuff when on shore power. You might get by with a 20a charger, but for the small difference i'd go for 30a, for example https://www.batterymegastore.co.uk/...rgy-chargers/victron-energy-bpc123044002.html

Shore power needs an RCD and MCBs for each circuit. If the AC ground is bonded to the DC -ve you need to fit a galvanic isolator.

You don't have enough batteries. 2x110ah leisure batteries would be the bare minimum for a 33ft boat, plus an engine battery, which can just be a suitably sized car battery.

The 1-2-B switch isn't a good solution for a modern cruiser, you would be better off with a starter battery, on its own switch and at least a pair of domestic batteries, also connected to their own switch. A 3rd switch gives emergency engine starting from the domestic bank, amongst other things. You will need to add some split charging then, if you don't already have it.
 
Sea-Fever said:
I didn't appreciate that a smart charger is not affected by additional load whilst charging, in which case there is no need to isolate the batteries from the 12v system when charging.

Not sure about an inverter with such a small battery bank.....not with my wife's hairdryer in her holdall!!

So I have 2 x 110ah batteries.....what charger would you (anyone) recommend. I can't see a situation where I want to operate the windlass on shore power but definitely the fridge...most other things are small fry.
Click to expand...

A small 200 - 300W inverter may well be useful for charging laptops etc and your wife could use low power straighteners but any inverter powerful enough for a conventional mains hairdryer is not going to be realistic. You can get 12V hairdryers but I understand that they give out so little heat that your marriage is more likely to end up on the rocks than the boat. ;)

Richard
 
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