RutlandMike
New member
I've lost my 12v power but the 24v is fine. I've taken the boat apart and can't figure out what's wrong with it. Can anyone recommend a good marine electrician in/around Windsor please? Very frustrating and I've given up.
12v expert required!
- Thread starter RutlandMike
- Start date
pappaecho
New member
Before you go to the stage, of an external electrician, ask yourself how you get both 24 and 12 volt power.
Do you have, for example, separate 24 and 12 volt batteries.
If not then ask your self how you have got 24 and not 12, and could it be that there is a 12 volt converter from 24 volts?
That could be a very good starting point, and it may just be something as simple as a fuse.
If you can give a little more details as to the battery banks, and charging from the engine, I am sure that the forum will be able to help. If the boat is a particular make and is supplied with 12 and 24 volt as standard, then there may be others who have had the same problem
Do you have, for example, separate 24 and 12 volt batteries.
If not then ask your self how you have got 24 and not 12, and could it be that there is a 12 volt converter from 24 volts?
That could be a very good starting point, and it may just be something as simple as a fuse.
If you can give a little more details as to the battery banks, and charging from the engine, I am sure that the forum will be able to help. If the boat is a particular make and is supplied with 12 and 24 volt as standard, then there may be others who have had the same problem
ccscott49
Active member
More than likely a 24-12v converter, find that, find your problem.
VicS
Well-known member
What about 24 volts being supplied by two 12 volt batteries in series with the 12 volts being taken from the mid point (in otherwords from just one of them) A connection there come adrift, or faulty isolator switch.
First step has got to be finding out how the 12volts is supplied as PE asks in his first sentence.
First step has got to be finding out how the 12volts is supplied as PE asks in his first sentence.
ccscott49
Active member
That is a very bad way of getting 12 volts, not reccomended by anybody I have ever talked to on the subject. Apparently it does not do the battery bank any good atall, with batteries trying to balance and stuff.
So I doubt it's been done that way, I certainly wouldn't and dont.
So I doubt it's been done that way, I certainly wouldn't and dont.
poter
Active member
Why do you have 24volts on a boat?
all the kit is either mains or 12Volt yes?
don't understand /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
poter
all the kit is either mains or 12Volt yes?
don't understand /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
poter
VicS
Well-known member
[ QUOTE ]
That is a very bad way of getting 12 volts
[/ QUOTE ] that may be true but it is the simplest and cheapest way of getting a small amount of 12v power. However a peep at Mike's profile reveals that his boat is an Ocean 42. They were fitted normally with two 240 hp engines so on a boat of that class and size with that much grunt under the floor I should think it has quite separate 12 and 24 volt systems.
PE suggests there may be other forumites with the same boat but there won't be many as only 36 were made.
That is a very bad way of getting 12 volts
[/ QUOTE ] that may be true but it is the simplest and cheapest way of getting a small amount of 12v power. However a peep at Mike's profile reveals that his boat is an Ocean 42. They were fitted normally with two 240 hp engines so on a boat of that class and size with that much grunt under the floor I should think it has quite separate 12 and 24 volt systems.
PE suggests there may be other forumites with the same boat but there won't be many as only 36 were made.
William_H
Well-known member
24 volts is a commonly used voltage on large vehicles. This is primarily because of the power needed to start large diesel engines.
For the same amount of power 24 volts requires 1/4 of the current through wires switches and battery. Power equals voltage multiplied by current.
So if you have a large diesel engine it probably originates from a heavy vehicle where the starter and alternator were made for 24 volts. It would be quite foolish to revert to 12 volt components although possible because of the advantages of 24 volt system.
The 24 volts can be an advantage for even simple circuits like the mast head light. For the same power at 1/4 the current you need lighter wire. Not only that but any voltage drop in the wire represents a smaller percentage of total so matters less.
It is normal to get 12 volts for those devices which require 12 volts from a switching converter. This effectively transforms the voltage down. It means that if you need 10 amps at 12 volts you need feed the converter with 5 amps. (actually a bit more due to losses). This is far better than using a resistor to lose 12 volts power wasted in heat where 10 amps at 12 v0olkts would require 10amps at 24 volts. Likewise if you just tap a battery you will be taking 10 amps from half of the battery which really causes trouble when you try to supply the 10 amps from the 24 volt alternator via the unused battery.
I understand some new cars are going to a 48volt system for the same reasons. Likewise you see power transmission lines across the country at 132000 volts and more for the same reason. Higher voltage equals less current equals less copper required for really high power.
Reference the original poster. I'm sure someone can nominate an electrician who can help you, however as a skipper you really owe it to yourself to understand your system so that you can fix most things yourself. Especially when at sea. So if you do get an electrician make sure you get him to explain the system.
I don't believe you can treat a boat like a car. Just getting an expert when it won't go will cost a lot and leave you vulnerable to both being ripped off and being stranded. Boats are no where near as reliable as cars. good luck olewill
For the same amount of power 24 volts requires 1/4 of the current through wires switches and battery. Power equals voltage multiplied by current.
So if you have a large diesel engine it probably originates from a heavy vehicle where the starter and alternator were made for 24 volts. It would be quite foolish to revert to 12 volt components although possible because of the advantages of 24 volt system.
The 24 volts can be an advantage for even simple circuits like the mast head light. For the same power at 1/4 the current you need lighter wire. Not only that but any voltage drop in the wire represents a smaller percentage of total so matters less.
It is normal to get 12 volts for those devices which require 12 volts from a switching converter. This effectively transforms the voltage down. It means that if you need 10 amps at 12 volts you need feed the converter with 5 amps. (actually a bit more due to losses). This is far better than using a resistor to lose 12 volts power wasted in heat where 10 amps at 12 v0olkts would require 10amps at 24 volts. Likewise if you just tap a battery you will be taking 10 amps from half of the battery which really causes trouble when you try to supply the 10 amps from the 24 volt alternator via the unused battery.
I understand some new cars are going to a 48volt system for the same reasons. Likewise you see power transmission lines across the country at 132000 volts and more for the same reason. Higher voltage equals less current equals less copper required for really high power.
Reference the original poster. I'm sure someone can nominate an electrician who can help you, however as a skipper you really owe it to yourself to understand your system so that you can fix most things yourself. Especially when at sea. So if you do get an electrician make sure you get him to explain the system.
I don't believe you can treat a boat like a car. Just getting an expert when it won't go will cost a lot and leave you vulnerable to both being ripped off and being stranded. Boats are no where near as reliable as cars. good luck olewill
RutlandMike
New member
Thanks all - I couldn't agree more. Believe me, getting in someone else for anything is always a last resort and I make damn sure I'm watching what they're doing. In this case I have had to admit defeat due to everything being beautifully secured in trunking. To trace all the cables back manually would be extremely difficult, especially as a lot of stuff would have to be removed (generators etc) to be sure of correct tracking. I'm hoping that a qualified sparky will have voltmeters etc that can trace the 12v supply - I'm just likely to short something out if I go fumbling about with something conductive. Does anyone know anyone who can help??? Please???
lenseman
Active member
- Joined
- 3 Jun 2006
- Messages
- 7,077
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- South East Coast - United Kingdom
I'm not too far from Windsor, I was born there some years ago /forums/images/graemlins/grin.gif.
I could take a look and try to sort out the problem for you like, just give me a ring?
I could take a look and try to sort out the problem for you like, just give me a ring?
RutlandMike
New member
You're a star Dave
PM sent
/forums/images/graemlins/smile.gif
PM sent
/forums/images/graemlins/smile.gif
andyball
New member
[ QUOTE ]
For the same amount of power 24 volts requires 1/4 of the current through wires switches and battery. Power equals voltage multiplied by current.
[/ QUOTE ]
umm, power of 24Watts needs 1Amp on 24V and 2A on 12V , so not 1/4 , but 1/2 of the current. /forums/images/graemlins/blush.gif
For the same amount of power 24 volts requires 1/4 of the current through wires switches and battery. Power equals voltage multiplied by current.
[/ QUOTE ]
umm, power of 24Watts needs 1Amp on 24V and 2A on 12V , so not 1/4 , but 1/2 of the current. /forums/images/graemlins/blush.gif
G
Guest
Guest
There are a lot of Mobos with 24V ... in fact.
G
Guest
Guest
It may be a bad way to do it ... tapping of 12 etc. ----- but it's not only some boats that do it ... some trucks do it from their twin battery banks ...
With a mobo that is charging its batterys far more than a Sailboat etc. - then surely it's a lesser problem ... batterys will be in better charge state and regular.
With a mobo that is charging its batterys far more than a Sailboat etc. - then surely it's a lesser problem ... batterys will be in better charge state and regular.
pheran
New member
[ QUOTE ]
24 volts is a commonly used voltage on large vehicles. This is primarily because of the power needed to start large diesel engines.
[/ QUOTE ] Thats not the way it is arranged on my boat. The 24V is used only for the domestics and bowthruster and is derived from 2 x 230Ah batteries in series. The engines, including starting, remain at 12v from two 2 x 180Ah battery banks. Any 12v requirement in between is supplied by a number of 24 - 12 V converters although most of my ancilliary stuff, plotter etc, seems able to work off anything in the 8 -32v range. The engines have both 12v and 24v altenators.
24 volts is a commonly used voltage on large vehicles. This is primarily because of the power needed to start large diesel engines.
[/ QUOTE ] Thats not the way it is arranged on my boat. The 24V is used only for the domestics and bowthruster and is derived from 2 x 230Ah batteries in series. The engines, including starting, remain at 12v from two 2 x 180Ah battery banks. Any 12v requirement in between is supplied by a number of 24 - 12 V converters although most of my ancilliary stuff, plotter etc, seems able to work off anything in the 8 -32v range. The engines have both 12v and 24v altenators.
Andrew_Fanner
New member
I have two banks of 2 x 12V coupled in series. The bank attached to the S/H engine have no alternative connection, the P/H set have a central tapping for 12V. My switches have a 0,1,2,Both for 24V which selects both pairs for Both and a 0,1,2,Both for 12V that appears to treat the P/H battery set as two independant 12V sources that still charges at 24V across the series pair. I have yet to work out precisely how this is set up but its a so far best guess. I have also yet to work out what is going on if I have 24V#2 (which is the 12V enabled side) selected as well as the 12V Both.
Any Thames based reader who cares to look and provide a definitive answer will doubtless get beer
Any Thames based reader who cares to look and provide a definitive answer will doubtless get beer
