Wiring batteries for failure and charging

[Guest]

We have a Dahler 38 CWS.
We would like to know how to wire (1) the domestic and engine batteries so that we can start the engine from the domestic batteries should the engine battery fail (2) the engine battery so that we can charge it from the shore supply through the installed charger for the domestic battery (3) the domestic and engine batteries so that we can charge them from a single wind generator.

We have the original wiring diagram but it does not have these features.

 

[oldharry]

A charge splitter, and suitable heavy duty switches set up in the way described in most books on boat wiring, such as "The 12 volt Bible" will suffice. Have a look at the books in your local Chandlery - all you need to know will be there (at least, if you are UK based!).

But first check whether your Domestic battery is a 'Lesiure' type, designed to run low loads. If so, you will soon destroy it if you use it to start the engine, as they are not designed to supply the heavy current neede for engine starting. Conversely, Starting batteries are often unsuitable for the deep cycle discharge of a domestic battery, and will also go down much more quickly.

Charging requirements will probably be much the same for both, and both can usually be wired directly to the charger through a charge splitting diode and switches. The splitters instructions will show you how.

 

[ZEBEDEE]

I have just done the same job to my Bav 34 for code of practice inspection. I used a single Battery isolation switch and some heavy duty cable and works a treat if you need to charge the engine start battery just make the switch to put it in parallel with the domestic bank. However I do not think that you will need too under normal use.
If you start getting into splitting diodes etc that I assume that you have from your alternator then you are into compensating for the 0.6v drop across the diode.

 

[bryantee]

Go to adverc web site and copy their reccomended ideal boat system . you need not buy their adverc system,just follow the principle . cost max 3 switches at £10
Each and a 1,2,both, off at about £25. some 300 amp fuses for the battery links at £5 each and your in business.http://www.adverc.co.uk/

 

[Robin2]

I presume your sign means "danger, man at work"

 

[bryantee]

No, trying to cope with windows M E,With 20 20 hindsight 98 was a much better vintage < G >