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One wire alt, thoughts?

1K views 11 replies 8 participants last post by  colojeepguy 
#1 ·
Looking to see what are some pro/cons to a one wire alt set up.
 
#3 ·
I have run both. My big alternator is a one wire. It works well for winching but is hard on belts since I run a v belt. I took it off and I am running the standard Jeep alternator which is not one wire. I also run a isolator and dual batteries. I really don’t see a difference from a user stand point.
 
#5 ·
My big alternator was built by Texas Alternator and had a smaller pulley which was suppose to put out 50 amps at idle. I have no way to measure it. It did charge the batteries faster when winching.
 
#7 ·
ONE WIRE doesn't have an 'Excite' circuit.
It relies on RESIDUAL magnetism in the rotor to get charging, so the 1,200 RPM (or more) to get it charing isn't uncommon.

With 'Excite' to the rotor, the rotor IMMEDIATELY becomes magnetized (Excited) and the alternator charges if it's turning fast enough.

Low speed charging suffers from the same issue.
No Excite, no full strength charge at low RPM.

The 1 wire can actually SUCK amps at low RPM instead of producing anything, so if you do a lot of low speed operation or idling, it's not the best idea.

Also keep in mind that if you store your Jeep or don't drive it for long periods of time, the 'One Wire' regulator will draw amperage when the vehicle isn't running, It's not a lot, but it will add up over time and suck the battery down.

The longer you leave a 'One Wire' set, the higher you will have to rev it to get the alternator charging again.
Sometimes the rotor looses ALL residule magnetism and you have to MANUALLY excite the rotor again to get it charging.



That's another point, unless the 'One Wire' regulator is set up to OVERCHARGE the battery in operation, You never quite get that battery to full 'Final Charge' status for the reason mentioned above by Zillla.

Overcharging a battery just kills it quicker than slightly undercharging it, but it's still a dead battery when it doesn't have to be when you could have got another couple of years out of it with no issues.

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Actually, a 'GROUND' WIRE to the alternator housing will do more good than a 'One Wire' will in most cases.
 
#8 ·
Thanks for the input guys. Bored at work today and one of our old aircraft tugs had a dead alt. Just a plain old 10si. Took it apart to find the brushes we gone and had one diode out on the tree. Standard Army thinking is to get a new one for a bazillion dollars that takes 6 months to show up. Pulled some money out of the coffee fund and bought a rebuild kit ($15 bucks). While rebuilding it one of the guys ask why we didnt put in a one wire, more or less told him the same thing that JeepHammer said about charging at idle. The tug spends most of the time at idle or slightly above.
 
#9 ·
good for you BHawk ... i work for the fedgov too (civilian) and even though i'm a supervisor I end up doing a lot of maintenance around the facility because it would cost 50x as much and take months to get approval for the repairs, put it out for bid, then wait for the repairmen to show up. just wanted to send a thanks for thinking outside the box and saving the taxpayers some money!

plus i just learned why my alt has two wires :)
 
#10 ·
... Edited...

Plus i just learned why my alt has two wires :)
The GM SI series should have 4 wires...

The smaller (#1 Position) in the plug is the 'Excite' wire.

Gets things charging right away, keeps the alternator making power longer as the RPM goes down.
It's also a 'Ground' (through the rotor) when the alternator isn't charging,
But turns 'Positive' as the alternator starts to charge.

This means with a wire through your ignition switch (Switched Power) to this terminal,
Then ran through a light bulb on the dash, you can have an 'Idiot' light on any common SI alternator.

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The larger (#2 Position) in the plug is the 'Sense' or 'Line Sample' wire.

By getting rid of AMC's 'Short Cut' on installing,
You can move that 'Sample' source back someplace it will do some good,
Like AFTER the fuse block someplace,
And the alternator will start to produce enough to supply the fused accessories without the voltage dropping, your lights dimming, ect.

This wire can hook to full time power, it won't suck the battery dry.

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The big wire on the back, the 'BAT' terminal is the feed to the battery positive.

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The big wire IT SHOULD HAVE is a dedicated 'Ground Path' wire back to the battery Negative.
Another AMC screw up...

If you are going to give a direct path for POSITIVE, doesn't it make sense to give a direct path to Negative to get that circuit completed?

Nothing like trying to drive 40 amps of current through a 2 amp 'Ground' connection that is mostly rusted bolts, corrosion, painted metal, ect...
Then complaining about the lights not working, low volt gauge readings, ect.
 
#11 ·
I was a Tango back in the day as well.

I remember our tugs ran on mogas, and someone put JP8 in it at the fuel point... It didn't start running like crap and die until they were about half way across the flight line.. :laugh:
 
#12 ·
I've been running a 1 wire alternator for over a decade with no issues. You do have to rev the engine slightly to get it to start charging, but after that it will charge at 600 RPM. My last battery lasted 9 years, and the alternator never drained it while sitting for long periods. (I don't drive it a lot in the winter, so sometimes it sits for several weeks in an unheated garage without starting).
Overall a much better setup than the stock 40A Motorola alternator with separate regulator.
 
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