Tim wrote:

you said, something like : Why don't you use a combiner(Isolater)?"

Actually, I'm going to make my own. A commercially bought isolator
(combiner) is actually

a three(for the most common) post device, which has "Alternator output"
on usually the center post, and "Bat.1" on another, and "Bat 2" on the
third. And this contains a couple heavy diodes to allow the alt to
charge simoaniously both battery banks, yet, leave the bateries
independant of each other. And that's a good idea.

The problem I have with the commercially made products, is that if one
diode diode goes out. Then the whole combiner, as you say, is bad, that
is, unless you wish to press the diode pac out of the finned aluminum
heat sink, and dig through the epoxy, and finally figure out that
you're fairly well wasting your time trying to repair the unit (that
is, unless it's made to be repaired), only to have to go buy another
one.

Tim

I have already covered what I would do and reccomend in my other reply
but I thought you would appreciate that my opinion of the commercial
diode isolators is no higher than your own.

For the price they are they ought to have heavy 24 carat gold plated
terminals and a gold plated pure copper heatsink not just some cheap
alternator diodes pressed into a P.O.S. turn to white powder in a season
aluminium heatsink.

Our yacht had a P.O.S. LUCAS isolator in a can and the previous owner
had been going through batteries like they wern't rechargable.
Fortunately the yard had just put a new set on and had had them on
charge while the boat was laie up.

When I took the isolator off the bulkhead to tidy up the wiring and
clean up and paint the rusty bracket, I found the aluminium can had
corroded right through and the transformer oil it relied on for cooling
had leaked out. It would have been fine if it had had a strip of
plastic tape round it from new seperating the two different metals.
The diodes were pretty well cooked, one was hard shorted and the others
were high resistance which meant one battery was getting less than an
amp of charging current :-( I was inspired to chuck it in the nearest
bin. Not what you want to find just before your first trip 'going foreign'.

You might appreciate this Lucas humour if you haven't seen it befo
http://www.mez.co.uk/lucas.html

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
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'Stingo' Albacore #1554 - 15' Early 60's, Uffa Fox designed,
All varnished hot moulded wooden racing dinghy.