New battery wiring - DIY advice needed

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alldownwind

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I'm making some big changes to my boat battery setup this winter, fitting a third battery, paralleling the existing two, and also fitting isolator switches.
I'm wondering how best to provide the new wiring, specifically how to fit the terminals on the cables. Tried the soldered joints in the past, using a blowlamp, didn't have great success with that. Are there crimp-on fittings available, if so do Hire Shops carry crimpers?
Or can I buy pre-made cables at different lengths, complete with terminals already fitted? Maybe from e.g. Halfords?
Any advice gratefully received.
 
If it is for cable up to 6mm2 any Halfords type place have the crimps and crimpers - I prefer a ratchet crimper that gives a double crimp. For larger cable mechanically clamped battery terminals are available but for ring terminals I'd suggest you have a bit more practice at soldering - it's not rocket science! Pleny of flux, get the lug good and hot, put the cable in and feed solder in until it starts to spill out - job done!
 
Did this last year and found cheapest (non-tinned) wire was from a car shop in the Medway industrial estate (makes a difference if you need a few m of it!), and my marina crimped the ends on for me (FOC). The crimps are available in the chandlers - just make sure you are getting the right size - best to take the bits with you that will take the fitting.
 
I used self-fit jobs from Caravan shop ... They have screw clamps to grip the wire ... and then you put on battery terminal, close top down locking onto post.
Never had any trouble with them .... caravans put similar loads on their gear as we do - and they do well there ...

Cable ? Even with clamps fitted - car breakers ? Plenty of starter motor cables etc. there .... Or go to Halfords for cable ...
 
I did similar 3 years ago making a complete submains system for the two extra leisure batteries which I fitted.
The best place for stuff is the local electrical wholesaler, and I used the double insulated and colour coded copper wire used to provide "meter tails". The inner insulation layer is either red or black, and the wire bends easily so can be threaded through lockers etc easily. It is good for 100 amps. You can also get metal jointing blocks which are brass or chome/brass, which have a series of connection holes, big for the cable input, and small for outputs via fuse/breaker panels to the individual circuits.
I also sourced 24 volt lorry cable, which as I remember was 10 core ( 5 pairs), good for up to 24 amp per pair, and colour coded
so that each circuit could be individually assigned and a wiring diagram drawn up. I had four circuits, one for each cabin and a fourth for the cockpit. I got copper spade connectors again from the electrical wholesaler, and properly crimped them. Dont use the steel ones from car shops..
Finally I had a lot of problems with "marine cigar lighter" units. Which were installed one in each cabin. Items such as mobile phone chargers would not make proper contact and had to be waggled to get them working. A pump for inflating the dinghy drew 10 amps, and the socket got red hot. I found the answer in Maplin.......
They sell gold plated terminal pairs, which serve three different purposes. Firstly you can plug colour coded red/black banana plugs into the terminal ends. Secondly you can clamp spade connectors with the screw terminals. Thirdly and in extremis, you can partly unscrew the plastic terminal and put bare wire through a hole in the terminal and then clamp down. My dingly pump has no problems with the banana plugs and does not overheat.
They are about £5 each, and cost less than the "Marine cigar lighter" units.

Good luck
 
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I also sourced 24 volt lorry cable, which as I remember was 10 core ( 5 pairs), good for up to 24 amp per pair, and colour coded
so that each circuit could be individually assigned and a wiring diagram drawn up.

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Trailer cable ... is a good alternative ... easily sourced from caravan shop / car acc's shops etc. It has multiple cores all insulated and coloured. My reasoning - it puts up with trailers and all the abuse ... it carries high ampage to run caravan fridges while charging van batterys etc.

I have a truck with 24V systems ... the cables are stiff and unwieldy and IMHO an overkill .... but IMHO.
 
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be carefull not to over-tax your alternator with two (possibly large?) batts wired in together.

If you can get to Ramsgate you could see Alan at Marlec, he will make up cables with whatever ends you need.

[/ QUOTE ]With the geatest respect you can't over tax an alternator by wiring two batteries together.

The immediate effect is that the alternator will just take longer to charge the batteries.
 
Too true. I stand corrected. /forums/images/graemlins/smile.gif

What is it called when an alternator runs for longer than it was designed to, at an output right on it's opperational limit?

edit- Other than 'hot' /forums/images/graemlins/laugh.gif
 
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Too true. I stand corrected. /forums/images/graemlins/smile.gif

What is it called when an alternator runs for longer than it was designed to, at an output right on it's opperational limit?

[/ QUOTE ]
Boatman is right - it's called 'hot' and alternators tend to be self regulating to a degree. As they heat up, their output drops. An average 90Amp alternator very very rarely gives out 90 Amps for very long for the following reasons:

Firstly because the if batteries can accept 90 Amps its not normally for long. The initial 'surface' charge is at a high rate, but then the internal resistance of the battery rises as the charge has to penetrate the plate.

Secondly and perhaps more importantly, because the alternator gets hot and the internal resistance rises and 'self limits' its output.

It would be a dull alternator designer who didn't allow for ample cooling at high charging currents, but the cooling is not enough on most alternators to keep them at max charge. Its enough to stop them self destructing, but not enough to keep them cold. Heat limits the output.

This is another reason why specialist high output alternators don't come cheap either. But this is probably just as much to do with the lack of economy of scale in the manufacture as well as supply and demand.
 
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<span class="small">It would be a dull alternator designer who didn't allow for ample cooling at high charging currents, but the cooling is not enough on most alternators to keep them at max charge. Its enough to stop them self destructing, but not enough to keep them cold. Heat limits the output.</span>

[/ QUOTE ]

Wow. So all the alternators that have to be replaced were faulty to start with?

Dont worry, I am only kidding /forums/images/graemlins/wink.gif
 
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With the geatest respect you can't over tax an alternator by wiring two batteries together.


[/ QUOTE ]

Normally not. But if you have an old-type alternator regulator you can!

I blew mine while charging 3 X 105Ah half-charged batteries in parallel. Since then I have a semi-automatic system /forums/images/graemlins/smile.gif. I installed an amp-meter, passed the booster's field cable through a switch and turn it off when I see a current > 60A. After a while I turn it on and finish my beer(s)...
 
I have 400 amp capacity on 2 x 200 amp banks, charged by a 28 year old Perkins 4108, using the oldest alternator on the planet (35amp), so old that the charging regulator is the size of a small book - they dont make them like that any more
 
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I'd suggest you have a bit more practice at soldering - it's not rocket science

[/ QUOTE ] Everything must be clean. Remember with soldering cleanliness really is next to godliness and as Steve says plenty of heat so that you can work quickly.
 
The problems I had were to do with heat. I clamped the terminal, hollow end upwards, fluxed it, blasted it with a blowtorch and virtually filled it with molten solder. Trouble came when I tried to slowly push the (obviously not hot enough) wire into it, expecting that with the torch still going the wire would be hot enough, but of course it wasn't, the solder immediately solidified, and in the process of recovering the situation I kept ending up with what looked like a dry joint.
Worried too about heating the wire as the covering gives off poisonous fumes, doesn't it?
If someone can help out here with chapter and verse on how to do this successfully, I'd be grateful.
 
Cut back the insulation a couple of inches,
Thread on two or three pieces of heat shrink,one slightly longer than the other two,
Clip two mole wrenches onto the bare wire - these will act as heat sinks,
Tin the wire, tin the fitting
Fit them together - heat - run in solder.
Leave to cool ( don't use water to cool)
Shrink the 2 short sleeves on and then the longer one and bob's yr uncle .
 
Not sure that soldering is a good idea.
Firstly you are introducing dis similar metals in close proximity and this will encourage corosion.
Secondly you are creating a "hard" spot where the solder ends and with the inevitable vibration this will eventually lead to the cable fracturing.
I believe that crimping is a better solution and any car electrician should have the necessary crimpers and probably be able to do the job in situ.
 
When soldering a cable to a lug I don't even attempt to tin the wire first - copper is so conductive on larger cable I think it would be nigh on impossible.

Put flux on both the lug and cable, heat the lug then put the cable into the lug THEN introduce the solder - when everthing is hot ethough it will work.
 
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