Does anybody know

[Becky]

if one can buy a dual-output alternator that will charge both the engine battery and the domestic battery bank individually with a smart charging system. We have heard that possibly Bosch might make such a thing, but a search of their web site revealed no further information.
Hope some of you clever guys know about such things.
Regards Becky

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[pvb]

Yes...

Yes, you can buy dual-output alternators. However, if you are using a "smart regulator", it's probably easier just to use a blocking diode system - the regulator will compensate for voltage loss across the diodes.

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[Nickcf]

many cruisers use dual output alternators to charge both battery banks separately, so they are readily available.

The simple ones use a bolt on diode pack on the back of the alternator to split the charge to the two battery banks. The voltage sensing wire is connected to the battery side of one of the outputs to overcome the small volt drop caused by the extra diodes but it all works extremely well. Might even be possible to convert your existing alternator.

There are often specialist alternators repair places around that could give you all the practical advice. They do auto repairs primarily but the alternators are basically the same and they usually know all about dual charging units. Look in yellow pages under 'Car Electrics' for suppliers who specialise in alternators/starter motors.

When my Volvo Penta alternator packed up recently the replacement from Volvo was over £300. The yellow pages guy completely rebuilt it with new bearings, control unit and diode splitter in 24 hours for £60! Looked like and works like, new.

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[boatmike]

No need. You only need a blocking diode with one input and 2 outputs. Suggest your "smart charger" senses the charge in the battery bank that is more liable to discharge (service battery) If you don't understand electrickery very well I recommend a fairly cheap book. "Boat Electrical Systems" by Dag Pike. Very simple and easy to follow with a section dedicated to charging systems. Much cheaper than a new alternator! Adlard Coles about £15.... and will tell you exactly how to wire it in.

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