Alternator produces 13V

[Carslil Jim]

I just got my 85 County with two batteries and inbuilt fridge back from the workshop after some serious gearbox work, to be informed that they had tested the alternator and it was only producing 12V. I put my voltmeter on it and got a reading of 13V.

Is 13V eneough? The garageman said I should have 14V.

[THE BOOGER]

Should put out about 13.8 volts if less you may have a problem:( test it with motor running but no load electrically every thing off and see what it is puting out and again with a load let us know whats happening

[Relay]

13V with that much load (2 batteries and a fridge) is -okay-...not great but okay. Assumably you're still running the tiddly little alternator your county came with? They're not overly powerful. If you can, check the current output rather than the voltage. If it's above 10 amps it should be fine. You've gotta remember to check it at the back of the alternator too...since the battery is quite a long ways; voltage drop in the cable is reasonably common (and can be fixed by replacing the cable!)

[101RRS]

I recently had my alternator tested at 13v at the rear of alternator. Still charges up the battery up to 13v not 13.8 so is not being charged to 100%.

The auto electrician said the alt is on the way out at 13v and should be replaced real soon.

Garry

[richard4u2]

alternators have bushes the same as a generators dont they ? if so have a look at the bushes first

[Lionel]

alternators have bushes the same as a generators dont they ? if so have a look at the bushes first

I think you mean "brushes".

Both generators and alternators have brushes, but the generator uses a commutator, to provide a DC output directly. This is segmented and causes more wear on the brushes than the smoother slip-rings in alternators, where DC is gained by solid state regulator circuitry.

The low voltage output could also be due to a fault in the regulator circuitry. If its an older alternator these can be adjusted, if everything else is OK, but practically all alternators these days are internally regulated, so adjustment is not usually available.

Cheers,

Lionel

[Michael2]

probably a diode gone on the back. Don't ask me for any more tech info, but that's what I've been told about alternators that charge at less than 13.8V.

I'd remove all the load, and just keep one battery to it, and then check to see what it's charging at.