Small boat, Wiring

[terrymay]

Hi All
I'm about to rewire my boat, nothing too grand, just running lights, cabin lights etc. I've looked at some diagrams on the net and apart from the fuses there does'nt seem to be any voltage regulator/surge control between the battery and the lights, is this correct? I'm undecided as to use the original Dyno-start that's fitted to the engine or, connect an alternator to charge the battery. Would this make a difference to the above?
Regards Terry.

 

[VicS]

No you would not expect to find a regulator between the battery and the lights There isn't on your car is there? The only problem that can arise is if the alternator or dynamo regulator goes faulty and it starts pushing out too high a voltage. Even then although the life of the bulbs will be shortened (particularly halogens) the first sign of the problem is likely to that the battery is overcharging.

Fitting an alternator will increase your normal maximum charging rate but unless you have a large demand for electrical power and large battery banks to recharge you probably will not need it. If you fit an alternator you will still have to retain the Dynastart for starting the engine unless it can be modified to accept an ordinary starter motor. If you do fit an alternator you will have to consider pulley sizes to ensure that it is running in its correct speed range

Fitting an alternator will not affect the wiring etc for the lights. You should regard the stystem as all powered by the battery which is merely recharged by the alternator or dynamo.

(Remember that disconnecting a running alternator from the battery is a sure way to blow its diodes)

It sounds as though you would benefit from reading one of the range of books on the subject of boat electrics but you may also benefit from the notes HERE It is theoretical rather than practical but it will help you understand some of the concepts.

Do not forget than voltage drop on long cable runs is the enemy of 12 volt systems and is the reason for heavier cable being used than would be used for the same current at 240volts. I think elsewhere on the above site there is a guide to cable sizes.

 

[terrymay]

Many thanks for reply and info, the site is very helpful thanks again - Terry

 

[Bajansailor]

So much useful info on boat electrics at the TB Training website you mentioned above - thank you Vic for posting the link to it.

 

[whiteoaks7]

I realise this is a bit of a bee in my bonnet, but please think carefully about the wire and connections you're going to use. There was a post a day or so ago on this subject.