Idea: Alternators send AC to Wind type Controller at house bank

[dave777]

There are a number of wind turbine controllers of various power ratings which take AC and regulate charging of 12V or 24V systems. AC wiring doesn't need the size, weight & expense of DC cabling and there is much less transmission loss.

Yanmar specifies a relatively short distance between alternator and the bank to be charged, the voltage drop is related to twice the actual distance because it's two wires + and -.

With a catamaran, our house bank is not close to either engine and consequently we've never had good charging from the engines.

[billknny]

You totally misunderstand.

The reduced wire size has nothing to do with AC vs DC, but rather is a function of the voltage produced. 120 VDC uses the same size wires as 120VAC.

A 12V (nominal) Alternator prduces 12V AC before rectification. Transmitting the AC power will save nothing.

If your alternator is not charging you batteries, are the wires properly sized for the amperage produced and distance traveled?? If they are, the problem is elsewhere.

[dave777]

Thanks for that, just read up on the subject.


The wires are definitely undersized, but part of the problem is the distance between the engines (on a catamaran) and the house bank is way too large.


Maybe external regulation for the alternators with direct sense from the house bank would help. I've got solar with MPPT which tops them perfectly when used lightly but need the engines charge better.

[smac999]

how big is the alternator, how long is the run, and what size wire is it?

and how is it connected to charge multible battery banks? (house and engine likly ?)

make sure it's not going through a diode isolator. they suck power

[rom]

Originally Posted by dave777

AC wiring doesn't need the size, weight & expense of DC cabling and there is much less transmission loss.

Quite the opposite, cf. skin effect. FWIW, I am using 70sqmm cables for about 14m round trip, 200A@12V alternators. That leads to about 0.5V loss. I can leave with it. I removed the bluesea switch in the path (it was getting real hot), so now I need to remove the fuse when working in the engine room.

[Bycrick]

Skin effect? At 60 Hz in copper, the skin depth is 8.5 mm. So with 70 mm2 wire, it should be negligible.

[Dsanduril]

Ahhhh, but the OP is proposing sending wild AC from the alternator which is dependent on alternator RPM. Typical is 400-600Hz but depends on engine speed, pulley ratio, and number of poles. And that gets the skin down to ~3mm.