Why ?

[pvb]

Problem with an alternator is it doesn't do the job under about 3000 revs. With my pulley sizes that's 950 on the engine, which ticks over at 450-500. No difference with a bigger output, so although mine is 40 amp and I run a lot of equipment my biggest demand is 28 amps which is achieved at engine revs 1100, so bigger output is not the answer. Smaller pulley, yes but cripple the belts, the only answer is Adverc.

A booster such as the Adverc can't increase the ability of the alternator to produce current, it simply increases the batteries' ability to accept current by raising the charging voltage.

 

[affinite]

I took the alternative approach.
Fortunately we are in the Med so I increased my solar panel size to a modest 160W with a decent regulator, replaced all lights with LED etc etc.
In the Med I get up to 8.5Ahr from the panels while the boat is "peacefully" sitting at anchor.
No need for a noisy engine to be running at all.
Next job - replace fridge insulation and poss fit keel coller then Im done.
I have to confess to feeling quite smug looking at all the boats plugged into shore power when in harbour

 

[sailorman]

A jump lead or a dedicated bridging switch - never a 1-2-Both!

with a 1-2 both one can access the other battery bank @ the flick of a switch if the engine battery goes duff

 

[Graham_Wright]

Because if you have two alternators charging 2 battery banks, you don't need a 1-2-Both switch, it will only confuse. Two simple on/off switches are all that's needed.

That risks an alternator output being open-circuited.

 

[Marsupial]

That risks an alternator output being open-circuited.

Correct, which is why I suggest removing the faulty alternator from the engine is the best solution, the problem then is if the faulty device is on a belt that services other devicres like a water pump - what then? In effect the only real reason for two alternators is the 12v 24v argument. When push comes to shove the redundancy argument is too hard KISS!

 

[fisherman]

Correct, which is why I suggest removing the faulty alternator from the engine is the best solution, the problem then is if the faulty device is on a belt that services other devicres like a water pump - what then? In effect the only real reason for two alternators is the 12v 24v argument. When push comes to shove the redundancy argument is too hard KISS!

Twin alternators in my case would involve one belt each side, both round the the water pump, so one belt gone and the other still drives. I carry a link belt for the water pump in case the alternator bearings give up.

 

[pvb]

That risks an alternator output being open-circuited.

Not necessarily - it depends how the wiring is done. You can wire the alternator output directly to the battery (obviously fused).