12V electrics ... HELP!!

[eastcoastbernie]

I try to be practical and do as much maintenance as I can on my boat, but have to confess to being a complete failure when it comes to electrics.

I've looked on the bookshelves at boat shows for assistance and brought home volumes promising to teach me all I need to know. Once home, I sit down to read them. Rarely get past the first chapter.

Does anyone out there know of a book that really is aimed at someone whose sole experience of electricity is plugging it in and turning it on?

OK, I've wired up the odd instrument or two by looking very closely at what I've got already and copying that for the new instrument. And I've soldered one bit of wire to another and found that to work. And used things oddly named 'choc boxes' which are not the sort the man in the dark wet suit brings.

But start to talk of amps and ohms and stray currents and earths and .... god help me .... galvanic isolators and serious glazing over takes hold.

I really would like to understand. /forums/images/graemlins/confused.gif

 

[fireball]

Ah ....


Amps - how much current is flowing (like the number of ppl walking through a corridor)
Ohms - a measure of resistance (how wide is the corridor?)
Stray Currents - this is where a number of those ppl walking down the corridor find a quicker way to their destination which you don't want them to take

Earths - ah ... now you're into 240v mains territory ... I'll let someone else take over..

 

[stephenh]

Re: 12V electrics ... HELP!!

Buy and read Alastair Garrod's " Electrics Afloat" publisher Adlard Coles around £20
very good for beginners like you ( and me !)

 

[Richard10002]

[ QUOTE ]

OK, I've wired up the odd instrument or two by looking very closely at what I've got already and copying that for the new instrument. And I've soldered one bit of wire to another and found that to work. And used things oddly named 'choc boxes' which are not the sort the man in the dark wet suit brings.

But start to talk of amps and ohms and stray currents and earths and .... god help me .... galvanic isolators and serious glazing over takes hold.

I really would like to understand. /forums/images/graemlins/confused.gif

[/ QUOTE ]

If you've wired things up, and they work, and progressed to advanced soldering, then you are well ahead of the game.

For whatever you are fitting, you need a wire thick enough to carry the current, which originates from the positive side of the battery, a fuse to protect the wire, (i.e. it blows at a lower current than the wire capacity), probably a switch, and a same thickness wire back to a negative bus, via the switch. The negative bus is just a convenient place for all the negatives to end up, then it has a thick wire back to the battery negative.

Amps x Volts = Watts everything you are talking about is 12v, most things have either watts or amps printed on them, so you can always find the amps it will draw through the wire.

Thickness of the wire is dictated by amps and distance run by the wire, (there and back), and there are tables for this.

It's almost as simple as that - I think.

I have picked up what I know from here and from watching an electrician do some work on my boat that I couldnt do at the time.

Still frightened of soldering, and Ohms, (resistance), still leaves me a bit confused.

All the books I have read leave me a bit confused, (although those that use an analogy with water have helped), but when it's put into practice, or an explanation of the particular issue is provided here, it tends to become clearer.

12volthandbook.pdf

search for the above - it helped me a bit, although I didnt get much further than the water analogy.

Also The 12 Volt Bible for Boats is good

Cheers

Richard

 

[jj1000]

Hi there

The main thing to know is 12V is the stuff that makes your tv go 'plink' then refuse to play anymore....

Have you looked at PBO's own Electrics Afloat by Allistair Garrod? It couldn't save my tv but it's much more readable than other sleep inducers on the subject.

Cheers John

 

[Talbot]

soldering gets a lot simpler if you do a few things

use a 240v iron - the 12v ones are rubbish I use a 15-20 watt iron through an inverter.

get the wire clean - fine if it is new, but for older wire, I always give it a decent clean with a bit of 600 grade wet/dry spreading out the individual pieces so they all get a bit of a clean, and then twist up and give a final wipe over with the wet/dry.

put a bit of soldering flux on the bit to be soldered. most solder comes with flux in it, but especially on the finer wire, there is never enough to make the soldering easy. Dont use great daubs of it, as it will only melt and stain the carpet as it drips down! The flux helps to clean the parts to be soldered.

apply hot iron that has a small blob of solder on it (helps heat transfer) the flux wil suck up the solder, and apply a bit more solder if necesssary (I like to use the thin wire solder as it stops me putting too much solder on the component.

hold the two parts together long enough for them to cool and for the liquid solder to solidify! (Easier if one part is held in some form of clamp)

If the iron is hot and the bits clean, and the hands steady, the heat transfer is rapid, and the solder flows immediately allowing the iron to be removed quickly, and preventing the insulation from melting.

If possible keep any component that has a melting cover with the bit to be soldered at the top (heat rises). spend a short period soldering anything within reach and it soon becomes a simple operation.

 

[Evadne]

Conceptually, most folk find the plumbing analogy easiest to understand: replace volts with water pressure and amps with flow rate. A high resistance is a narrow pipe and a low resistance is a wide one, a leak is self explanatory. /forums/images/graemlins/smile.gif

You might find this of some help as well.

 

[jj1000]

Re: 12V electrics ... HELP!!

Oops - sorry StephenH didn't notice you'd already suggested that book. Must be a good one!

Another comment, to my mind the most important thing with 12V is to avoid creating a fire hazzard from overheating and arcing. Wire thickness and good connections are the key.

By the way if you can order Electrics Afloat from boatbooks.co.nz , or you might be able to get it nearer to home!

John

 

[wotayottie]

might sound a bit harsh to say this, but the problem is that you are prepared to say "I cant do electrics" just like some people proudly say "I cant do sums" when they would never admit to "I cant write / read" - something which is much harder to learn!

the plumbing analogy is a good one, and if you just imagine the wires as pipes complete with branches and restictions you wont go far wrong. you only have to remember that whilst water goes off down a drain, the by now tired (lower voltage) electrons have to trundle back into the battery. so you have to have a complete round circuit with electricity - a one way trip isnt possible.

water has pressure which is a function of how high the header tank is. leccy has volts and for practical purposes these have the same effect. more volts across a resistance is just like more water pressure across a narrow pipe - the result is a greater flow in both cases. water has volume and leccy has amps - both fulfilling similar functions.

personally I wouldnt bother with books - mostly they are as boring as h*ll. instead, just learn as you install bits in the boat. but have in mind that its pretty simple or most electricians couldnt do it!

 

[NealB]

I was in very much the same state of ignorance, till I read...

"The 12 volt bible".

Maybe my brain was super receptive that afternoon (many years ago now), or maybe there was something in the air (it was cold, wet, wild and blowing a gale, and we were enjoying a long power cut)...

Whatever the reason, every word of that book made absolute sense to me, as I read it by the flickering flames of the coal fire.

Strangely, I'd had the book on my bookshelves for some years, often thumbed, but never before studied.

Now, I would certainly not call myself an expert, and I am horribly slow at electrical problem-solving, but I have done quite extensive boat rewiring jobs, and at least I can usually find out (eventually) why something has stopped working.

As for ac, however, I am still totally 'in the dark'.

So..The 12V bible" gets a BIG recommendation from me.

Good luck.

 

[Guest]

Re: 12V electrics ... HELP!!

[ QUOTE ]
Buy and read Alastair Garrod's " Electrics Afloat" publisher Adlard Coles around £20
very good for beginners like you ( and me !)

[/ QUOTE ]

Seconded ... it is very good and illustrated well. You will get advise about 12V bible etc. - yes - great IF you have understanding of electrics already ... which you admit is a black art to you...... so ignore those ...

Go for Garrods book .... I have plenty others, incl. 12V Bible and usually fall back to Garrods .....

 

[MrCramp]

Re: 12V electrics ... HELP!!

I understand boat electrics but I have read some of the "good" books on the subject and don't think they compare with the notes available on the web site run by Tony Brooks. I think he was/is a part time lecturer at some technical college but he does appear to know what he is talking about and all the notes, which you can download easily from his web site, are easy to understand and take a very practical/common sense approach.

I have not been on any of his courses but would suspect that they might be worth you considering. I remember reading good reports about them on a canal boat site, and also I think on this site a couple of years ago.

This is the link to the site. Click on Boat electric notes for what you want but I am sure you will find the other information interesting. It will be cheaper to use the free downloads and save and print them off than it will be to buy any of the books mentioned so far. I have read/seen most of them and would not buy any of them.

http://www.tb-training.co.uk/index.htm

Hope this is usefull.

 

[Guest]

12V soldering iron ...

I have a cheapo bought from Maplins ..... excellent bit of kit and heats up fast ... has fine tip so can do some amazing stuff. It runs from a standard ciggy socket .....

I've stopped carrying my 240V job now - even on the Baltic Crossing not so long ago when the engine solenoid contact broke off ... it did a grand job ...

 

[KenMcCulloch]

[ QUOTE ]

personally I wouldnt bother with books - mostly they are as boring as h*ll. instead, just learn as you install bits in the boat. but have in mind that its pretty simple or most electricians couldnt do it!

[/ QUOTE ]
Errr well I think that's probably quite irresponsible advice actually. Another thread here has been about a yacht on fire and 12v electrics are perfectly suitable for setting a boat on fire esp if wired by someone who has just learnt by doing without recourse to any collected wisdom in the form of a book. I have also found the 12Volt Bible very helpful as an electrical semi-literate myself. No it's not very complicated but it is potentially dangerous and requires care and attention.

 

[ShipsWoofy]

I wont add anymore to the confusion your thread has generated, other than, Good Luck!

Bet you're glad you did not ask which is the best anchor!

/forums/images/graemlins/laugh.gif

 

[whipper_snapper]

Re: 12V soldering iron ...

I use one of these gas powered jobs

Plenty of power for reasonably heavy duty soldering, but fine enough tip for fiddly stuff. With a micro blow torch for really heavy duty soldering.

And it has a rope cutter blade.

 

[VicS]

Re: 12V electrics ... HELP!!

[ QUOTE ]
the notes available on the web site run by Tony Brooks

[/ QUOTE ] I'll second that suggestion. A very simple and easy to understand explanation of the basics.

 

[Talbot]

Re: 12V soldering iron ...

I have had 2 x 12v ones. neither lasted much longer than a year.

I have had 2 x gas soldering irons. Both of those failed after abt a year. whereas my 240 one plus a 300w inverter was cheaper than the gas iron and seemingly will last for a very long time. Only replaced the last one cause the tip was worn out and I couldnt be bothered to find a new tip.

 

[Guest]

Re: 12V soldering iron ...

I reckon I was lucky to find this particularly one ... I know others who have binned 12V irons ...

The only time I have trouble is when a cold breeze is blowing across the work !! as the iron can't keep work temp up like a 240V one ... so it's out of drafts and close any through air-ways !!

I kept looking at Gas powered ones ... to cut rope as well ... but considering my 12V cost about £5 .... was far cheaper and works well.

 

[Guest]

[ QUOTE ]
......... I have also found the 12Volt Bible very helpful as an electrical semi-literate myself. No it's not very complicated but it is potentially dangerous and requires care and attention.

[/ QUOTE ]

I've just pulleed out my copy again to check my view on it ... yep - still I think it's not up to Garrods book. OK it' explains a lot of stuff to us non-electrical people ... but that's it really ... it's a book of no solutions or wiring. Also it is dated and my version is not exactly up to todays standards ... mines the year 2000 reprint ! So should have been a bit more up to date !

No Garrods PBO book gets my vote !!