One wire alternator wiring Electric Power steering pump

Hi

Im switching to an Mercedes Electric powersteering pump. Today Im running the Borgesson saginaw. I also have a 1 wire alternator without the external Charing relay.

I want wire the pump so it only runs when the Alternator is charging. The pump has 3 wires. +12 volt, ground and , 12volt igntion. Is it possible to set it up.

Regards Rob

What kind of one wire alternator? You can get to the stator connection or wire on some. You could then use stator voltage to activate a relay inline in the wire from the ignition switch. The stator should provide voltage only when the alternator is charging. The stator typically supplies 6 to 8 volts, so will likely require a relay with a 6 volt coil. Not a lot of them around now, a place that specializes in VW Beetles might have something like that. The load across the relay contacts should be fairly low, so shouldn't take a real heavy duty relay.

What kind of one wire alternator? You can get to the stator connection or wire on some. You could then use stator voltage to activate a relay inline in the wire from the ignition switch. The stator should provide voltage only when the alternator is charging. The stator typically supplies 6 to 8 volts, so will likely require a relay with a 6 volt coil. Not a lot of them around now, a place that specializes in VW Beetles might have something like that. The load across the relay contacts should be fairly low, so shouldn't take a real heavy duty relay.

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I'm kind of with Don on this one.  In an alternator the stator is the stationary winding.  The Delco 10SI one wire alternators I have seen are three phase, and the AC output from the stator gets rectified through some diodes to create DC output.  What is regulated is voltage applied to the rotor.  More voltage on the rotor = more voltage generated on the stator.  I'd be inclined to carefully pull apart the alternator and see if you can attach a couple wires to the brush wires wherever they attach to the internal regulator.  You can use an aerosol can straw to restrain the brushes during assembly.  Fire the car up and rev it so the alternator flashes.  Measure what DC voltage is being applied to the rotor via the brushes using a multi-meter on your newly customized alternator then purchase a DC coil relay that is compatible with whatever voltage your alternator is applying to the rotor to generate normal voltage.  Be sure to measure the engine when revving, as the applied voltage may drop when engine RPM is raised.  All this being said it might work, or you might find that the voltage applied to the rotor varies too much to be of any use.

You might also be able to use a fancy tach or ignition control box that has programmable output contacts.  That could be set to close above 500 rpm for example and therefore your power steering pump would only run when the engine is running.

Or- you could go back to the old tried and true - a belt driven pump.

Thanks

The whole Electric system in the car is changed to 12 volt, no more original wiring. Its a one wire tuff stuff alternator that goes directly to the battery. I like the idea of the programmable output. I have the MSD6AL and the Sniper unit. Thanks for helping

Regards Rob

Your car came with 12 volts.

Good luck on your conversion to electric power steering. Let us know how it goes, a write up on it would be great, others might like to do it.

I'm curious as to why you only want the pump to work when the alternator is charging? 

Why not wire the pump to a switched circuit, so that it is only on when the key is on. Unless you spend alot of time parking with your better half listening to the radio with the key switched to accessory :whistling:

Hi

I will let you know how it will go, yes I can wire it to the ignition no problems.