Battery switch.

[Henry]

I recently bought an O'day 27 and have come across a surprise in the wiring
of the battery switch.

This is the usual 1,2, both or off.

The two batteries are wired with their positives strapped together, and the
negatives disappear separately into the switch.
All positives are taken from the deep cycle battery, including the starter.


Tomorrow I intend to remove the switch with a view to rewiring in a more
conventional way.

Can anyone speculate on why the wiring should be as it is. Also, is there
anything I should know to prevent blowing the alternator?

Thanks in anticipation

Henry

 

[Henry]

NEVER, EVER MOVE THE BATTERY SWITCH WITH THE ENGINE RUNNING......

Switching ground in this manner is idiotic at least, negligent or
dangerous at most. STUPID comes to mind, also.

Yes I know. We all know. In fact I have training and some experience in
electronics, but not marine electrics.

That is why I was asking for assistance.

I did not say that I intended to move the battery switch while the engine
was running, although my switch can be safely moved provided it is not
turned off.

I was hoping for sensible advice, and calling me stupid is not called for.

If anyone has anything useful to say, I would value opinions.

That's another one for my block list!

Henry

 

[John Smith]

Calm down old man. He has asked for some advice.

 

[Tan PS]

Possibly the switch faulty and works in one position only. With the switch
out, check that the switch positions work (verify the contacts) before
fitting everything. Saves you the hassle of ripping it out again if it is
faulty.

Tan PS

 

[BruceM]

I've reread your original post three times & still can't work it out. First
you say about the two batteries. Then you say something about all positives
are taken from the deep cycle one.
Does that mean you have three all up?
If that is the case then I suggest that the motor has been setup from the
deep cycle one. OK.
The other two sound like they have been setup just for accessories like
fridge, radio, lights etc. OK.
The way they have the switch will be OK for that I reckon as really it is
only used to break the circuit. Doesn't really matter if the earth is broken
or the positive.
As long as whatever the wires are connected to are in the right order it is
OK. I mean positive to the radio positive etc.
The main reason you never see the earth broken on a car is so that if the
device earths out (metal?), it will activate it.
On a car the vehicle is all negative. (earth)
On a boat it is (usually) all wired back to the battery. (both wires)
BruceM

 

[Jürgen Spelter]

Hi Henry,

looks like You have a funny boat!
Normally the negative pole of battries is grounded by connecting them to
the metal parts of the boat. If in Your case it`s the other way around it
seems so, that the positive pole of Your battries is grounded. That will
work quiet good, it`s only unusual.
You can`t change that, because the positive pole of alternator will be
grounded too in Your boat. In europe, some old french cars have the same,
positive pole is connected to the matal chassis. Everyone trying to operate
a normal car stereo had a problem!

If it is as it seems, don`t worry. Everything works well, only plus and
minus are changed. So the two negative poles will lead to the battry switch.

By the way: these battery switches are in common use, but I think, You
should trough it away. In position ALL both battries are charged by running
machine, but also they are discharged, when machine stops. Better is to use
a relais, connected to the alternator light in the dashboard. This relais
connects the batteries, when machine runs. It also disconnect them, when
engine stops. When You then connect all lightning, pumps an so on to the
second battery, only this one will be discharged and starting battery will
stay well charged.....


regards

juergen

 

[Rob]

I recently bought an O'day 27 and have come across a surprise in the wiring
of the battery switch.

This is the usual 1,2, both or off.

The two batteries are wired with their positives strapped together, and the
negatives disappear separately into the switch.
All positives are taken from the deep cycle battery, including the starter.


Tomorrow I intend to remove the switch with a view to rewiring in a more
conventional way.

Can anyone speculate on why the wiring should be as it is. Also, is there
anything I should know to prevent blowing the alternator?

It sounds like an English car wired by LUCAS

 

[John Smith]

Hi GW, thanks for the reply,I am hoping to go down the battery combiner
road when I get to that stage of progress. Don't know where you are but I am
UK based. boat is about 30 miles from home in Suffolk so it is a bit of an
expedition when I go to do any work on it. When I learn how to do it I will
set up a web site and post some pictures of the project. many thanks to all
the people who post technical info on here. I have learned a lot but still
pick up new tips from other peoples experience.
best wishes to all
Peter