Isolated Earth Alternators?

[powerabout]

What your view on isolated earth alternators, jap and european engine marinisers seem to use them and US ones usually dont?

[pistnbroke]

presumably they want to wire the house system insulated return and put the starting battery with its own alternator next the engine doing only that job.
presumably the yanks have decieided its not worth the effort/cost and the only things which need them by law are petrol tankers ...

[goboatingnow]

Why dump DC negative transients through the block when you don't need to. If you have access to a isolated DC negative, then it's a better solution

Dave

[DGreenwood]

I am a yank and I always build them isolated if I can and recommend to owners that don't have it, to change it over. If sending units do not have a double pole setup then it is kind of moot isn't it? That is the second part of the that PITA to change over.

[powerabout]

correct
but who ever changed a block out because the charging earth ran through it to the neg battery terminal and damaged it?

[DGreenwood]

Originally Posted by powerabout

correct
but who ever changed a block out because the charging earth ran through it to the neg battery terminal?

Huh?...You only need to change the alternator and sending units.

[BertKu]

The advantage is that one can then have 2 alternators running on the diesel and have the 12 Volt and 24 Volt batteries charged.
Bert

[powerabout]

Originally Posted by BertKu

The advantage is that one can then have 2 alternators running on the diesel and have the 12 Volt and 24 Volt batteries charged.
Bert

you dont need isolated earth to do that.

So whats the problem you are solving with isolated earth?

[goboatingnow]

Impressed current corrosion.

[powerabout]

Originally Posted by goboatingnow

Impressed current corrosion.

How will you notice that is happening to your engine?

[michael pierzga]

Corrosion in Exhaust system, pumpshafts, heat exchangers...anything wet.

[powerabout]

Michael
Whats the physics of that, what is the circuit that is running via the sea water ( other than normal 2 dissimilar metals in an electrolyte) that involves the negative/earth of the battery/alternator

[michael pierzga]

How do you know that the current is negative ?

[powerabout]

Originally Posted by goboatingnow

Impressed current corrosion.

cant find any info on that
but plenty of corrosion protection systems by using Impressed current

[michael pierzga]

Yes indeed..it is possible to deploy an impressed current corrosion protection system. I have used them...not cheap...and they must be constantly monitored.