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Wombat 94 alternator load resistor

Posted: Sun Apr 24, 2016 5:36 am
by Bill2001
My 1973 Wombat 94 has a load resistor that goes between the "HL" (headlight) terminal of the Ignition switch and a chassis Ground. This terminal also branches off the ot "AC" side (??) of the Emergency Switch in the Headlight shell. It's mounted on the battery box and doesn't show up on my schematics. I think it's an add-on accessory to prevent overvoltage? Is it necessary? What should the resistance be (I've not measured it yet)? It looks ratty-- is a replacement available?

The original wiring worked OK but looked a tad crusty, so as long as bike was On The Lift and I was On A Roll (two very dangerous phrases), I decided to do new wiring.

And as an aside, if the Ignition Switch is a little sticky, a quick spritz of powdered lock Graphite works wonders.

--Bill

Re: Wombat 94 alternator load resistor

Posted: Sun Apr 24, 2016 6:27 am
by Dale
Bill,
I believe that this is the current limiter that the 94A was equipped with. Designed to save the headlamps but was less than effective. It should be replaced with a voltage regulator. The VR's from a Road Toad or 03 Wombat are often used.
Dale

Re: Wombat 94 alternator load resistor

Posted: Sun Apr 24, 2016 7:03 am
by Bill2001
Got 'em at SH: Wombat 03 -Hodaka Part#_23040 - Voltage regulator (RS2203) (same as the 02 RoadToad)

I'm going to look into upgrading the Headlamp (and maybe brake/tail light) with brighter and lower current draw LEDs and will be using an LED constant current driver module to provide consistent voltage/current to the LEDs. It would be a good idea to regulate the alternator voltage, even though the LED CC driver will work with a range of input voltages.

--Bill

Re: Wombat 94 alternator load resistor

Posted: Mon Apr 25, 2016 4:59 am
by Bill2001
Got one on order from SH.

Do we understand the principle of operation? On this Permanent Magnet type of alternator the voltage rises with engine speed and continues to rise unless regulated. The voltage regulator on this system typically senses the voltage output and "shunts" the excess voltage to ground. In effect, it puts an electronically-variable resistance load in the system and turns the excess volts into heat.

--Bill

Re: Wombat 94 alternator load resistor

Posted: Thu Apr 28, 2016 7:49 am
by Bill2001
The "Hodaka Part#_23040 - Voltage regulator (RS2203)" should arrive tomorrow. The parts manual shows the VR is fitted to a bracket on the frame backbone behind the ignition coil. Do-able and "correct" but I'll have to ship some zip-ties and move some wiring to weld the new bracket. Functionally, would it work as well bolted to the right side of the battery box?

--Bill

Re: Wombat 94 alternator load resistor

Posted: Thu Apr 28, 2016 11:43 am
by Dale
I chose not to weld additional brackets to my frames and just used a small u-bolt behind the coil bracket. It fits just fine and is not visible.

Re: Wombat 94 alternator load resistor

Posted: Thu Apr 28, 2016 12:28 pm
by rlkarren
I have a battery bracket that had the Current Limiter mounts on it and used those. If your battery bracket has those mounts I would suggest using them also. Simply use a piece of small gauge angled steel, (you can easily make one), and attach the VR to it so that when attached, it tucks in right under the battery bracket.

These are the brackets I mentioned:
s-l1600.jpg
$0.02

Roger

Re: Wombat 94 alternator load resistor

Posted: Thu Apr 28, 2016 12:57 pm
by Bill2001
Good. I've got alternatives. I'll see which strikes my fancy.

--Bill