Steve

Dear All

I am about to re-route the output of the alternator through a
(2-diode) 'battery combiner' to my 2 batteries. Should I connect the
outputs of the combiner to the battery side or the load side of the
main switches ? At present it goes direct to the load side.

It seems to me that if I put it to the battery side I cannot wreck the
alternator by turning off both batteries and Nigel Calder's book seems
to show this arrangement in most diagrams.

But how safe is this ? Is there a risk of a fault in the alternator
causing a short ? I would feel safer knowing that when both battery
switches are off the batteries are completely isolated.

What do people think ?

Thanks

Steve

Dave Moore

I would connect to the load side as if I ever need to isolate the battery I
want to isolate it from everything. It is then down to personal discipline
not to shag the alternator by disconnecting it when the engine is running.
Just make sure the switches cannot be accidently kincked etc.

Dave
"Steve" <ineverlookatthis@yahoo.com> wrote in message
news:f0d57f86.0311300948.2052062b@posting.google.c om...
> Dear All
>
> I am about to re-route the output of the alternator through a
> (2-diode) 'battery combiner' to my 2 batteries. Should I connect the
> outputs of the combiner to the battery side or the load side of the
> main switches ? At present it goes direct to the load side.
>
> It seems to me that if I put it to the battery side I cannot wreck the
> alternator by turning off both batteries and Nigel Calder's book seems
> to show this arrangement in most diagrams.
>
> But how safe is this ? Is there a risk of a fault in the alternator
> causing a short ? I would feel safer knowing that when both battery
> switches are off the batteries are completely isolated.
>
> What do people think ?
>
> Thanks
>
> Steve

Tony Brooks

"Dave Moore" <dave.moore@virgin.net> wrote in message
news:JVEyb.10816$O42.4508672@newsfep2-win.server.ntli.net...
> I would connect to the load side as if I ever need to isolate the battery
I
> want to isolate it from everything. It is then down to personal discipline
> not to shag the alternator by disconnecting it when the engine is running.
> Just make sure the switches cannot be accidently kincked etc.
>
> Dave
> "Steve" <ineverlookatthis@yahoo.com> wrote in message
> news:f0d57f86.0311300948.2052062b@posting.google.c om...
> > Dear All
> >
> > I am about to re-route the output of the alternator through a
> > (2-diode) 'battery combiner' to my 2 batteries. Should I connect the
> > outputs of the combiner to the battery side or the load side of the
> > main switches ? At present it goes direct to the load side.
> >
> > It seems to me that if I put it to the battery side I cannot wreck the
> > alternator by turning off both batteries and Nigel Calder's book seems
> > to show this arrangement in most diagrams.
> >
> > But how safe is this ? Is there a risk of a fault in the alternator
> > causing a short ? I would feel safer knowing that when both battery
> > switches are off the batteries are completely isolated.
> >
> > What do people think ?

Snap - have you ever seen an alternator that has developed a short circuit
in its main diodes - it dont half smoke!

If you ever fancy a quck dash betwee east & west coasts without going the
long way round, you would have to connect to the load side.

Tony Brooks

Iain Hibbert

Steve <ineverlookatthis@yahoo.com> wrote:
> I am about to re-route the output of the alternator through a
> (2-diode) 'battery combiner' to my 2 batteries. Should I connect the
> outputs of the combiner to the battery side or the load side of the
> main switches ? At present it goes direct to the load side.

> It seems to me that if I put it to the battery side I cannot wreck the
> alternator by turning off both batteries and Nigel Calder's book seems
> to show this arrangement in most diagrams.

I think that either you have mis-understood something, or you have
mis-written something or I have mis-read what you've written.

what is this 'battery combiner' exactly? If, as I suspect it is a
charge splitter (hence the diodes) then you have to connect to the
load side - or else only one battery will be charged at all, because
the diodes keep the batteries separate.

if its an automatic switch to connect the two batteries together,
then it wouldnt have a load side or diodes - only a connection to
each battery, a voltage sensing circuit and a solenoid switch.

iain

Steve

Steve <ineverlookatthis@yahoo.com> wrote:
>>> I am about to re-route the output of the alternator through a
>>> (2-diode) 'battery combiner' to my 2 batteries. Should I connect
the
>>> outputs of the combiner to the battery side or the load side of
the
>>> main switches ?

Iain Hibbert plunky@mail.com said.
>>I think that either you have mis-understood something, or you have
>>mis-written something or I have mis-read what you've written.what is
this 'battery combiner' exactly? If, as I suspect it is a
>>charge splitter (hence the diodes) then you have to connect to the
>>load side - or else only one battery will be charged at all, because
>>the diodes keep the batteries separate.
>>
>>if its an automatic switch to connect the two batteries together,
>>then it wouldnt have a load side or diodes - only a connection to
>>each battery, a voltage sensing circuit and a solenoid switch.
>>

Iain - It is what you are calling a charge splitter – just a pair of
diodes to allow current to flow into both batteries but not between
batteries. But I don't understand:

>>then you have to connect to the
>>load side - or else only one battery will be charged at all, because
>>the diodes keep the batteries separate.

The batteries will be completely separate (unless linked with the 3rd
switch); 1 connected to engine, 1 connected to services. I propose to
connect 1 output to 1 battery and the other to the other. If I make
this connection on the battery side of each battery's switch then both
will always get charge, if I connect it on the load side, each will
get charge only when its switch is ‘on'.

Or have I mis-undertood something ?

I put a rough sketch of my understanding of the 2 options on
http://www.liv.ac.uk/~kempsj/batterya2.gif - well it was more
interesting than what I was meant to be doing !

Thanks

Steve

Sandy Morton

In article <f0d57f86.0312020527.7d7cf717@posting.google.com >, Steve
<ineverlookatthis@yahoo.com> wrote:
> I put a rough sketch of my understanding of the 2 options on
> http://www.liv.ac.uk/~kempsj/batterya2.gif - well it was more
> interesting than what I was meant to be doing !

Why is the ouput of the diodes moving?

--
A T (Sandy) Morton
on the Bicycle Island
In the Global Village
http://www.sandymillport.fsnet.co.uk

Ronald Raygun

Sandy Morton wrote:

> In article <f0d57f86.0312020527.7d7cf717@posting.google.com >, Steve
> <ineverlookatthis@yahoo.com> wrote:
>> I put a rough sketch of my understanding of the 2 options on
>> http://www.liv.ac.uk/~kempsj/batterya2.gif - well it was more
>> interesting than what I was meant to be doing !
>
> Why is the ouput of the diodes moving?

Because he's trying to show off his ability to produce dynamic gifs?

No, it's because the question he's asking is whether it's better to
connect to the battery side or the load side of the battery isolator
switches. His diagram illustrates both possibilities. Your mission,
should you decide to accept it, is to pick one of the alternatives
and give your reasons for so doing.

Sandy Morton

In article <QZ8zb.18006$%%7.151270537@news-text.cableinet.net>, Ronald
Raygun <no.spam@localhost.localdomain> wrote:
> > Why is the ouput of the diodes moving?

> Because he's trying to show off his ability to produce dynamic gifs?

> No, it's because the question he's asking is whether it's better to
> connect to the battery side or the load side of the battery isolator
> switches. His diagram illustrates both possibilities. Your mission,
> should you decide to accept it, is to pick one of the alternatives and
> give your reasons for so doing.

In which there is no alternative:-)

--
A T (Sandy) Morton
on the Bicycle Island
In the Global Village
http://www.sandymillport.fsnet.co.uk

martin

On Tue, 02 Dec 2003 23:10:40 GMT, Ronald Raygun
<no.spam@localhost.localdomain> wrote:

>Sandy Morton wrote:
>
>> In article <f0d57f86.0312020527.7d7cf717@posting.google.com >, Steve
>> <ineverlookatthis@yahoo.com> wrote:
>>> I put a rough sketch of my understanding of the 2 options on
>>> http://www.liv.ac.uk/~kempsj/batterya2.gif - well it was more
>>> interesting than what I was meant to be doing !
>>
>> Why is the ouput of the diodes moving?
>
>Because he's trying to show off his ability to produce dynamic gifs?
>
>No, it's because the question he's asking is whether it's better to
>connect to the battery side or the load side of the battery isolator
>switches. His diagram illustrates both possibilities. Your mission,
>should you decide to accept it, is to pick one of the alternatives
>and give your reasons for so doing.

You forgot "don't hold your breath" and the poor bugger suffocated.
--
Martin

martin

On Tue, 02 Dec 2003 23:51:24 +0000 (GMT), Sandy Morton
<atm@sandymillport.fsnet.co.uk> wrote:

>In article <QZ8zb.18006$%%7.151270537@news-text.cableinet.net>, Ronald
>Raygun <no.spam@localhost.localdomain> wrote:
>> > Why is the ouput of the diodes moving?
>
>> Because he's trying to show off his ability to produce dynamic gifs?
>
>> No, it's because the question he's asking is whether it's better to
>> connect to the battery side or the load side of the battery isolator
>> switches. His diagram illustrates both possibilities. Your mission,
>> should you decide to accept it, is to pick one of the alternatives and
>> give your reasons for so doing.
>
>In which there is no alternative:-)

without alternating.
--
Martin

Iain Hibbert

Steve <ineverlookatthis@yahoo.com> wrote:
> Or have I mis-undertood something ?

no, I think it was me - I didnt look at the picture (I'm offline right
now) but I see what you are getting at anyway. You seem to have an
understanding of the risks.

I would put it on the load side of the switch so you can switch it
off if you need to, thats why you have the switch in the first place..
You can surely trust yourself not to switch it off while the engine
is running, and anybody else who comes on the boat just tell them to
leave things alone that they dont understand.

on the other hand, if you are likely to have people on board (middle
sized children maybe, confined to the cabin while you are motoring into
the marina) who might be likely to turn switches on and off then do
it the foolproof way.

iain

Jim B

"Steve" <ineverlookatthis@yahoo.com> wrote in message
news:f0d57f86.0312020527.7d7cf717@posting.google.c om...
> Steve <ineverlookatthis@yahoo.com> wrote:
> >>> I am about to re-route the output of the alternator through a
> >>> (2-diode) 'battery combiner' to my 2 batteries. Should I connect
> the
> >>> outputs of the combiner to the battery side or the load side of
> the
> >>> main switches ?
> The batteries will be completely separate (unless linked with the 3rd
> switch); 1 connected to engine, 1 connected to services. I propose to
> connect 1 output to 1 battery and the other to the other. If I make
> this connection on the battery side of each battery's switch then both
> will always get charge, if I connect it on the load side, each will
> get charge only when its switch is 'on'.
..
> I put a rough sketch of my understanding of the 2 options on
> http://www.liv.ac.uk/~kempsj/batterya2.gif - well it was more
> interesting than what I was meant to be doing !

Normal practice is to go from diode output direct to the battery.
Conveniently, this may be from the diode to the battery side terminals on
the battery switch.

The caution is to remember that this will be a permanently live high
amperage line, and its connections must be protected from accidental
earthing. The classic case is touching a spanner to the diode output while
working on the earthed engine body. Big spark, spanner welds to the
terminal, and in a couple of minutes you're on fire. So keep the lines from
diode to batteries as short as sensible (saves copper too!) and cover the
terminal connections.

If you have one or two battery banks and no diode (not recommended, but I've
seen it) then connect to the load side. This prevents your alternator output
from being permanently live (same welding problem as above). Also, with two
batteries you'll permanently be paralleling them (a fault in one kills the
other). .

--
Jim B, Yacht RAPAZ,
Sadly, for sale:
http://homepage.ntlworld.com/jim.bae...cification.htm
jim[dot]baerselman[at]ntlworld[dot]com