panhead not charging
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6th Gear
Joined: Dec 2005
Posts: 14
Likes: 0
panhead not charging
I recently purchased a custom chopper with a HD panhead engine. I did not get the bike from the builder and the seller knows very little about it. The bike was built and then sold right away and it has less than 200 miles on it.
The bike runs great but the battery is not charging. I know absolutely nothing about these electrical systems and I doubt it is OEM stuff so I am lost on what to check. It looks to be very basic but I am not sure how to troubleshoot it. Being that the bike was just built and has very low miles I am not sure if something went bad, or if it was never hooked up properly in the first place.
I have taken this of the alternator/generator? and there are only 3 wires involved. The one wire has positive 12v, the other terminal has nothing connected to it, and then there are 2 wires going to terminals that are labeled A and F. I have not been able to measure any voltages at either A or F.
Any ideas on what to check or what I need to to replace to get this working?
The bike runs great but the battery is not charging. I know absolutely nothing about these electrical systems and I doubt it is OEM stuff so I am lost on what to check. It looks to be very basic but I am not sure how to troubleshoot it. Being that the bike was just built and has very low miles I am not sure if something went bad, or if it was never hooked up properly in the first place.
I have taken this of the alternator/generator? and there are only 3 wires involved. The one wire has positive 12v, the other terminal has nothing connected to it, and then there are 2 wires going to terminals that are labeled A and F. I have not been able to measure any voltages at either A or F.
Any ideas on what to check or what I need to to replace to get this working?
Cruiser
Joined: Oct 2006
Posts: 148
Likes: 6
From: Wilds of Oklahoma
RE: panhead not charging
If you haven't worked with harley generators, take it to a shop that knows what they are doing. It will save you a whole lot of headaches and money in the long run. But if you must, here is a quick list of things to check:
1. Is it polarized? The generator will charge "backwards so you have to make sure it's charging in the right direction. Turn your ingition key on and take a jumper wire from the positive side of the battery to the "A" side of the generator, touch it briefly, you will get a spark. It is polarized now.
2. If that doesn't do it gound the"F" post to a ground and start the bike, rev it up a little,this should let the generator go to full output if it's working (the lights will get brighter ect.)or put a test light on the "A" terminal and it should glow brighter. If this works the gererator is working. Replace the regulator.
3.If this doesn't work unbolt the genorator and take it to a shop.
Now one work of WARNING: it takes almost nothing to frythe armature in the generator if the wireing is hooked up wrong, so be forwarned. The best suggestion is to let a tech do the whole thing and get it right before it leaves the shop. Good luck and be verrry thankfull that the guy that builtyour bike didn't put an old 3 brush generator on it.
1. Is it polarized? The generator will charge "backwards so you have to make sure it's charging in the right direction. Turn your ingition key on and take a jumper wire from the positive side of the battery to the "A" side of the generator, touch it briefly, you will get a spark. It is polarized now.
2. If that doesn't do it gound the"F" post to a ground and start the bike, rev it up a little,this should let the generator go to full output if it's working (the lights will get brighter ect.)or put a test light on the "A" terminal and it should glow brighter. If this works the gererator is working. Replace the regulator.
3.If this doesn't work unbolt the genorator and take it to a shop.
Now one work of WARNING: it takes almost nothing to frythe armature in the generator if the wireing is hooked up wrong, so be forwarned. The best suggestion is to let a tech do the whole thing and get it right before it leaves the shop. Good luck and be verrry thankfull that the guy that builtyour bike didn't put an old 3 brush generator on it.
6th Gear
Joined: Dec 2006
Posts: 11
Likes: 0
RE: panhead not charging
Good advice, Oldpanrider! My first test would be to re-flash. Only other thing you might wanna check.. I had a situation once where the guy who wired the bike zip-tied the wiring to the frame. He got the tie so tight it shorted the connection to ground (intermittently).
You mentioned a battery, so I'm assuming you're not running a mag. Otherwise I'd bet money on the re-flash LOL! Good luck!
You mentioned a battery, so I'm assuming you're not running a mag. Otherwise I'd bet money on the re-flash LOL! Good luck!
Stage I
Joined: Aug 2020
Posts: 1
Likes: 0
From: Ca
If you haven't worked with harley generators, take it to a shop that knows what they are doing. It will save you a whole lot of headaches and money in the long run. But if you must, here is a quick list of things to check:
1. Is it polarized? The generator will charge "backwards so you have to make sure it's charging in the right direction. Turn your ingition key on and take a jumper wire from the positive side of the battery to the "A" side of the generator, touch it briefly, you will get a spark. It is polarized now.
2. If that doesn't do it gound the"F" post to a ground and start the bike, rev it up a little,this should let the generator go to full output if it's working (the lights will get brighter ect.)or put a test light on the "A" terminal and it should glow brighter. If this works the gererator is working. Replace the regulator.
3.If this doesn't work unbolt the genorator and take it to a shop.
Now one work of WARNING: it takes almost nothing to frythe armature in the generator if the wireing is hooked up wrong, so be forwarned. The best suggestion is to let a tech do the whole thing and get it right before it leaves the shop. Good luck and be verrry thankfull that the guy that builtyour bike didn't put an old 3 brush generator on it.
1. Is it polarized? The generator will charge "backwards so you have to make sure it's charging in the right direction. Turn your ingition key on and take a jumper wire from the positive side of the battery to the "A" side of the generator, touch it briefly, you will get a spark. It is polarized now.
2. If that doesn't do it gound the"F" post to a ground and start the bike, rev it up a little,this should let the generator go to full output if it's working (the lights will get brighter ect.)or put a test light on the "A" terminal and it should glow brighter. If this works the gererator is working. Replace the regulator.
3.If this doesn't work unbolt the genorator and take it to a shop.
Now one work of WARNING: it takes almost nothing to frythe armature in the generator if the wireing is hooked up wrong, so be forwarned. The best suggestion is to let a tech do the whole thing and get it right before it leaves the shop. Good luck and be verrry thankfull that the guy that builtyour bike didn't put an old 3 brush generator on it.
- Ive already done the polarizing bit.
- Ive maintained all my own classic machines forever, it had no time this time.
- bike was a perfect running bike before this.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,939
Likes: 8,036
From: poway
So I know its been a while. But curious I recently took my bike to a shop and the tech wired my gen. Backwards on the terminals. I didnt notice because I wasnt even aware they had touched my gen. Then upon inspection I noticed wires were crossed. To say the least I was stranded and miss a couple meals that day hahahah. I brought the bike back to my shop, did some tests, ((I have a volt meter gauge on the bike and Ive always paid close attention)) its doesnt seem to be charging.
- Ive already done the polarizing bit.
- Ive maintained all my own classic machines forever, it had no time this time.
- bike was a perfect running bike before this.
- Ive already done the polarizing bit.
- Ive maintained all my own classic machines forever, it had no time this time.
- bike was a perfect running bike before this.
While it's better to start a new thread, none of what you are saying make any sense except that you generator stopped working.
But curious I recently took my bike to a shop and the tech wired my gen. Backwards on the terminals. I didnt notice because I wasnt even aware they had touched my gen
What did they do? What generator do you have? 2 brush or 3?
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,072
Likes: 1,006
having the service manual is a must. that said, we must assume your machine is using hd technology (hahaha).
i would bet that the machine does not use the mechanical regulator as upgrade to electronic is a plus. that said, they will self polarize the generator as the current flow is directional thanks to the P/N junctions of the semi-conductors.
on the mechanical regulator, everything is an electro-magnetic check and balances. if hooked up backwards, the contacts in it will vibrate severely and burn up, a good tell is the series resistor on the back side will be damaged.
there could be many factors that cause it not to work including mechanical issues internal to it. as an example, my 74ch would not work due to a laminate separation that shorted out a armature winding.
i would bet that the machine does not use the mechanical regulator as upgrade to electronic is a plus. that said, they will self polarize the generator as the current flow is directional thanks to the P/N junctions of the semi-conductors.
on the mechanical regulator, everything is an electro-magnetic check and balances. if hooked up backwards, the contacts in it will vibrate severely and burn up, a good tell is the series resistor on the back side will be damaged.
there could be many factors that cause it not to work including mechanical issues internal to it. as an example, my 74ch would not work due to a laminate separation that shorted out a armature winding.
Seasoned HDF Member
Joined: Apr 2010
Posts: 9,576
Likes: 7,953
From: Long Island, New York
If you do have a electronic regulator, they do not like shorts or other oddities in current. If the mechanic had the generator wired backwards, and the regulator is electronic, it is likely garbage and you need a new one. Then polarize the genny again and you should be golden. Good luck.
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Seasoned HDF Member
Joined: Aug 2008
Posts: 5,072
Likes: 1,006
well to further understanding,
1. what causes the generator to put out diff polarities of current?
2. the generator can be happy running positive ground as well as negative ground, why??
3. they make two mechanical regulators, one positive and one negative, how to tell the diff??
4. while over current can fry an electronic regulator, where is the frailty??
5. why does the P/N junctions help prevent reverse damage to within the operating parameter of the design or rating??
simple answers, tom terrific hats please!
1. what causes the generator to put out diff polarities of current?
2. the generator can be happy running positive ground as well as negative ground, why??
3. they make two mechanical regulators, one positive and one negative, how to tell the diff??
4. while over current can fry an electronic regulator, where is the frailty??
5. why does the P/N junctions help prevent reverse damage to within the operating parameter of the design or rating??
simple answers, tom terrific hats please!
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Joe Kucinski
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,939
Likes: 8,036
From: poway
well to further understanding,
1. what causes the generator to put out diff polarities of current?
2. the generator can be happy running positive ground as well as negative ground, why??
3. they make two mechanical regulators, one positive and one negative, how to tell the diff??
4. while over current can fry an electronic regulator, where is the frailty??
5. why does the P/N junctions help prevent reverse damage to within the operating parameter of the design or rating??
simple answers, tom terrific hats please!
1. what causes the generator to put out diff polarities of current?
2. the generator can be happy running positive ground as well as negative ground, why??
3. they make two mechanical regulators, one positive and one negative, how to tell the diff??
4. while over current can fry an electronic regulator, where is the frailty??
5. why does the P/N junctions help prevent reverse damage to within the operating parameter of the design or rating??
simple answers, tom terrific hats please!
1. Residual magnetism,
2. It really does not have any polarity,
3. Not sure why there would be a positive or negative regulator unless you are talking about the field windings.
4. Output transistor / diode.
5, cuz current only flows one way.