# Motorcycle voltage regulator

#### GaryRobb

Joined Nov 14, 2011
12
I want to build a voltage regulator for my motorcycle. I have done searches and just got completely confused. I hope you can help. I am running a small battery so the regulator will have to have low output. The battery is 12volt and the capacity is 10hr: 14ah. 12n- 5.5a-3b battery The only electrical on the bike is head lights and tail lights. The bike is kick start only. Any help would be very appreciated. Please just help me get started.
Gary

#### SgtWookie

Joined Jul 17, 2007
22,221
It is preferable to get a factory regulator for your motorcycle if you can find one.

What is the make, model and year of your motorcycle's manufacture?

Did it originally come equipped with lights, or not?

Does your bike have a magneto, generator or alternator?

#### GaryRobb

Joined Nov 14, 2011
12
My bike is a custom built with 1950's technology. It's 12 volt generator. The regulators are availible but get exspensive. I am on my third one in two years.

#### SgtWookie

Joined Jul 17, 2007
22,221
OK, so is it a Harley-Davidson?

The generator - was it originally a motorcycle generator?

Can you take some photos of it, and the regulator?

Does the regulator come apart easily?

#### bountyhunter

Joined Sep 7, 2009
2,512
My bike is a custom built with 1950's technology. It's 12 volt generator. The regulators are availible but get exspensive. I am on my third one in two years.
Bike's use a shunt regulator. The regulator has to be matched to the alternator output so it can handle the heat from the current it has to shunt.

#### debe

Joined Sep 21, 2010
1,226
Some pictures of the Generator & reg would help as motor bikes can have old style generators or altenators with brushes & reg just like cars only smaller.

#### GaryRobb

Joined Nov 14, 2011
12
I just recieved an e-mail and a voltage regulator I ordered is now on back order. I hope this picture helps. The voltage regulator comes mounted on the machined end piece and covered with epoxy. I soaked it in paint thinner and worked on it for two days. The regulator is only a few dollars of electronics but when mounted in the end cap the price goes up to $200.00. This end cap mounts on the end of the generator. The generator has two brushes. #### Attachments • 176.5 KB Views: 168 #### SgtWookie Joined Jul 17, 2007 22,221 Gee, those wires are all damaged where they went through the bulkhead. Can you show a better close-up of both sides of the circuit board, and the area where this assembly bolts on to the motorcycle? Thread Starter #### GaryRobb Joined Nov 14, 2011 12 This a view of the generator and the end housing (another end housing to the left). The ring to the right is what covers the opening where the brushes are. There are two wires coming out of the regulator (armature and field) and a pole to connect the battery. I will post a better close up picture later with a better camera. #### Attachments • 140.3 KB Views: 102 Thread Starter #### GaryRobb Joined Nov 14, 2011 12 This is a closer view of the board. The battery wire comes in and is soldered to a round black object to the right. Sgt. the wires were messed up when I was getting the epoxy off #### Attachments • 293.3 KB Views: 125 • 293.7 KB Views: 122 #### SgtWookie Joined Jul 17, 2007 22,221 OK, I think you were a bit too close to the board when you were taking those photos, as they are both out of focus. We need really clear, sharp photos of them in order to make out the details - I know that isn't easy to do. I usually have to take a dozen or so before I start getting some decent photos. Lighting is almost always problematic. The best lighting you can get is outside on a cloudy-bright day; as the lighting is very even - no harsh shadows; but waiting for a cloudy day just isn't very practical. Can you take some photos of the generator from the ends, and try to get some good details around the wiring? There are two studs/bolts/terminals w/nuts sticking out on the brush end. Are they both insulated from the frame? What connects to those studs/bolts/terminals? I know this process is kind of a pain in the neck to go through, but the information is really needed as we can't have "hands-on" with it. #### shortbus Joined Sep 30, 2009 8,337 The older style Harley voltage regulator was really a 'cut-out' not a true regulator. It 'cut-out' the voltage to the field at a certain voltage setting. When you "polarized" your generator, did you have the regulator connected? If so that will fry the regulator. The electronic style regulator CAN NOT be connected when polarizing the generator. Also was the reg, a Cycle Electric brand or a knock-off? The imported knock-offs are notorious for failing. Last edited: #### SgtWookie Joined Jul 17, 2007 22,221 The generator appears to be some kind of a retrofit of an original Harley 10A generator with a longer, finned end cap for an internal regulator. Here's what I'm talking about: http://www.greatplainscycle.com/Generators/Generators.php This looks just like the body of the generator: http://www.greatplainscycle.com/Generators/Harley12v65A.jpg those didn't come with built-in regulators. Example of an internally regulated Harley generator: http://www.greatplainscycle.com/Generators/Harley12v.jpg These appear to be completely newly manufactured units. The original vintage generators were rated for 10A. They could output 20A-30A, but they would burn up. So, the regulators for those generators had to be designed so that the generator current output would not exceed that 10A limit. If this custom motorcycle has more lighting & accessories than the original motorcycle did, or the current draw has been increased from stock (wouldn't be hard to do, even just changing headlamps to halogen would do that) then the generator would be in a constant overload condition. This would generate additional heat in the regulator, because it would have more of a voltage drop across it. Later model Harleys have the regulator positioned between the downtubes, in front of the engine. This avoids the problem of having the regulator enclosed in a unit that has no forced air cooling while the bike is idling and stopped. A linear regulator would be very hard-pressed to survive under such conditions; which is likely why he keeps going through regulators. Another good reason would be the shorting of wires to ground. I already commented in reply #8 that the wiring insulation was damaged. I didn't comment on the crimp-on connectors, but I consider those type very unreliable. I would use solder-type terminals, and insulate the joint with two layers of heat shrink tubing. This generator: http://www.nationsautoelectric.com/images/49-9700_1_.jpg looks practically identical for the body, except for lacking the finned end cap. Those were for 1965-1969 Harley Sportster & 1965-1981 Harley Big Twin, but are out of stock at that vendor. Here I'm getting much closer: http://www.sportsterspecialty.com/solid-state-regulator-w-chrome-end-cover.html That's for Sportsters, '65-'77. No fins on the end cap, which means those regulators would probably last a shorter length of time than the ones our OP has been buying. Not cheap at$95/ea, either.

It might be one of these:
http://www.brucerossmeyerparts.com/...=fidaa95zz~r=tidaa3389zzfidaa95zztidaa3389zz~
Even less cheap at $177. Odd, these look like the same thing, but ~$160:
http://www.brucerossmeyerparts.com/...UNTED-REGULATORS-detail.htm?productId=7748559

If you really wanted to get away from the solid state stuff burning up, you might revert to the original electromechanical relay-type regulator:
http://www.brucerossmeyerparts.com/...542&browse=261411&shopBy=15493&catalogId=1570

or else go with a solid-state regulator that you can mount in front of the engine as they did with the later models.

Whatever you do, you should check over your wiring harness very carefully, and repair any sections where the insulation looks worn/aged/cracked. As I mentioned before, I don't like those crimp-on splices and terminals; they just are not reliable when crimped. Solder and 2x shrink tubing works well. Be careful to not allow the wire to get too warm, as solder will tend to "wick" up in the wire; this will make it less flexible and more subject to breakage. Hemostats work well as a heat sink.

#### debe

Joined Sep 21, 2010
1,226
If you want to build a Reg this is a rough drawing of a Bosch type reg which may work in this aplication. The Tip125 needs a small heat sink. The diode in the line from the Armature to the battery must be big enough to carry the Generators total output current. This i think is probably close to the original concept. The indicator lamp is optional.

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#### SgtWookie

Joined Jul 17, 2007
22,221
Say Daryl,
Looks like you have the transistors drawn upside-down; the emitters for a PNP go towards the positive rail. If connected the way you have it drawn, the body diode in the TIP125 would conduct constantly from the armature output into the field winding; it probably wouldn't last more than a few moments.

#### GaryRobb

Joined Nov 14, 2011
12
The generator is a knock off I believe it is a volt tech. The information you guys are posting is great. A friend at work saw what I was trying to do, a close up picture. He had his camera with him and here is the results. And thanks

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#### shortbus

Joined Sep 30, 2009
8,337
@SgtWookie - here is what he is using on the end bell of the generator;http://www.cycleelectricinc.com/ Or as he said a knock-off.

Until 1958 all the used was a mechanical cut-out on Harley engines.

#### SgtWookie

Joined Jul 17, 2007
22,221
Starting from lower left, the black item is a resistor
To it's right (orange item) is a diode
To the right of that is another resistor oriented vertically
The tan item to the right is a capacitor.
back to the left, there is a missing transistor above the resistor
Above that there is a missing resistor or capacitor
The large round item on the left is likely a power diode
The rectangular item on the far right is either a MOSFET or a transistor.
Can you read the numbers on the face of it?

#### debe

Joined Sep 21, 2010
1,226
Hi Sarge. Went & double checked the circuit & they are PNP transistors. This is the original. Can you see where I may have gone wrong?

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