volvo alternator wiring

[ytd]

We have a volvo ( I think) 120A alternator on a volvo D55 saildrive with an external smart regulator. The regulator has failed and needs to be sent away for repair. I plan to fit a normal automotive type external regulator so the boat can be used in the interim. As well as the big b+ connection on the back of the alternator there are 2 spade terminal at right angles in a plastic connector. AFAIK the one closest to the centreline is the field but I have no idea what the other spade connector is for. Battery sense? warning light? tacho? Any ideas?

 

[VicS]

Unless it is a negative regulated alternator ( with which i am not familiar) the three connections for the regulator will be an earth connection, a connection to one of the slip ring brushes (possibly marked F) and one to the output from the field diodes which will also be the waning light connection.

Your owners manual should have a wiring diagram but you may also find the section on alternators in the electrical notes at www.tb-training.co.uk useful.

Get your regulator from a decent automobile electrician and seek his advice and get him to ID the connections on the regulator. It would be sensible to take the alternator with you.

 

[VicS]

Can i add check the fitting instructions for the smart regulator for any internal modifications that were made to the alternator which will have to be reversed.

 

[pvb]

Is this the standard-fit 115A alternator with external charge sensor? If so, I thought that the external charge sensor only compensates for voltage drop, rather than being a "smart" regulator. On that basis, it might be worth checking whether the alternator has an internal regulator already fitted.

 

[Billjratt]

We need info -what's written on 1 - the alternator, 2 the 'smart controller' If the latter is sterling, adverc or any of that ilk, the alternator already has a regulator, and will work like a car charger. On the alternator the terminals could be :
1 positive voltage out, 2 "F" the ignition lamp connection
3 an extra (possibly white wire) connection to the smart charger from the controlled brush 4 Negative out, which may be isolated from ground, or, the negative may just be connected to ground. (it depends on the type of starter motor installed)
So 1, thick brown wire? goes to your diode splitter or battery switch and then to batt +
2 thin wire goes to the ign light
3 forget if you don't use smart controller
4 thick black to fuse link or maybe no wire, just the mounting bolts. to batt-
First switch on Ign and see that lamp lights. if not, you do not have the field correctly wired. Current needs to flow from the batt+ through the ign sw, throught the ign lamp, through the field coil to the regulator, where it will be connected to B-.(ground)
This current needs to flow to create enough magnetism to kickstart the alternator.

If the lamp lights, start the engine and measure the voltage at B+ (the splitter diodes is a good place) it should rise to 14.8(ish) volts depending on the initial battery condition, and the ign light should go out. If there's an ammeter in the circuit you should be able to confirm charging state.
If the external regulator is still installed, you can test it by simply connecting the white wire mentioned above. All it does is act in parallel with the internal regulator and over-rule it to produce a high charge for longer. I realise this is a long post and may be a poisson rouge, but we needed more info to start with (photos?) good luck