'74 Shovelhead - kick only setup - Keeps killing batteries

[CupidsDeathDay]

Hey fellas,

So I bought a 1974 Shovelhead 1200 FL-FLH 74 CI last year. This thing is awesome, and I have thoroughly enjoyed riding it.

However, recently out of the blue, it has started killing batteries for no apparent reason. First thought was a possible grounding issue, so I went over all the wiring, and found no indications of deterioration or loose connections. After doing some spark testing, I noticed that one sides spark was super weak. So I had the coil tested, and sure enough, the attenuation on the coil was bad. Which was unsurprising considering how damn old the thing looked. So I replaced the ignition coil. She rode just fine for another week, but then the battery died again. I checked with my parts store to test the battery, and it was dead-dead. No way to recharge, and so I grabbed a new one. She started up fine, after a few kicks, and for a few days, then died again. After her home, I took the battery out, and back to the store. I thought maybe the battery was a dud, but it wasn't. So I came home with yet another brand new battery, and she killed it within another few days. Again, like dead-dead battery. So I pulled her into the shop again, and did some testing. Everything looks to be terminating correctly, and no loose wires, connections, and getting good spark. So I replaced the voltage regulator, and she ran for a few more days, the, died again. The new coil is testing just fine, and the regulator seems fine. So I don't know what to do from here.

The only other thing I can think of, is to replace the entire wiring harness or the stator coil.
The stator coil tested out fine in the shop, but could it possibly be bad?

Any help or troubleshooting advise would be nice.

[Tattooo]

It sounds like a dead short to me....... When you attach the + side of the battery with the - side hooked up does it spark?????? That's an easy way to start........

[TriNortchopz]

Did you do anything to it before it started killing batteries? could vibration be an issue? top of battery hitting metal seat base perhaps?
Did you check the voltage, using a multimeter, going to your battery at idle and at 2500 RPM?
What type, make and size of battery are you using?

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[rockman96]

It's not a dead short. If it was, the smoke and smell (or blown fuse) would be an obvious giveaway. But it could well be an intermittent and/or partial short. Get a good VOM and set it up for current... Put the leads (note polarity) between the battery ground and the cable end (which you removed from the battery), and see what it reads. Hopefully zero. If you have an obvious reading, then start isolating the circuits until you have a zero reading, and go from there.

I have seen an intermittent short do the same thing... Everything seems fine, and then (usually when you're riding) it will manifest. Check your wiring REALLY good to make sure there are no skinned points that can make or graze a contact point... Most notable the regulator to battery wire, and lights.

[Tattooo]

It's not a dead short. If it was, the smoke and smell (or blown fuse) would be an obvious giveaway.

Nope... It depends on the wire and the amount of voltage it won't smoke it will just kill the battery........ If the power is going somewhere it's not supposed at that time, it's a short to me...... + or a -...

[Tattooo]

CDD what kind of ignition switch do you have???????

[rockman96]

Nope... It depends on the wire and the amount of voltage it won't smoke it will just kill the battery........ If the power is going somewhere it's not supposed at that time, it's a short to me...... + or a -...

Nope. If its a dead short its gonna blow a fuse, or burn up some wiring. Period.

[JBinNC]

If the battery is slowly losing its charge (as stated, over a few days) then the most likely cause is an alternator that is not charging the battery, or at least, not charging enough to keep the battery up. A quick and easy test of the alternator is to test the voltage across the battery when the motor is running at about 2000 rpm, and with the lights on. A modern alternator in good condition should show 14.2 - 14 4 volts at the battery. If that voltage checks low, one of the components of the alternator is bad. Could be the voltage regulator, the stator, or the rotor. (And if that voltage checks high, on the order of 15V or higher, you have a bad regulator, or a regulator that is not properly grounded.)

Jim

[Divebarcustomsnj]

I could agree that it may be a charging issue. You can also do a parasitic load test if you have a multi meter that will test DC amps. Set the muli meter, swap the leads to the correct ports, with the bike off and remaining off for the test remove the ground from the batter and then put on lead to the battery and the others on the cable. If it's reading anything more than .40 volts then there is a faulty component in the circuit. start by removing fuses one by one to see if the volts drop. If there's a significant drop when you pull a fuse from from the head light when it's off, you'll know something is not right in that circuit.

[rockman96]

If the battery is slowly losing its charge (as stated, over a few days) then the most likely cause is an alternator that is not charging the battery, or at least, not charging enough to keep the battery up. A quick and easy test of the alternator is to test the voltage across the battery when the motor is running at about 2000 rpm, and with the lights on. A modern alternator in good condition should show 14.2 - 14 4 volts at the battery. If that voltage checks low, one of the components of the alternator is bad. Could be the voltage regulator, the stator, or the rotor. (And if that voltage checks high, on the order of 15V or higher, you have a bad regulator, or a regulator that is not properly grounded.)

Jim

Definitely go through what JB said first to verify the charging system is good. But if you're killing batteries to the "dead dead" point, I think its going to be a parasitic issue. It could be a combination of the two as well.

[Tattooo]

Nope. If its a dead short its gonna blow a fuse, or burn up some wiring. Period.

Nope.. What do you call a stator that goes to ground???????

[Tattooo]

The only other thing I can think of, is to replace the entire wiring harness or the stator coil. The stator coil tested out fine in the shop, but could it possibly be bad?

Any help or troubleshooting advise would be nice.

Since no one has asked and you didn't really said and people are just giving random answers without knowing, When is it actually killing the battery???? Is it when your riding it or sitting over night or both?????

[rockman96]

Nope.. What do you call a stator that goes to ground???????

A stator that goes to ground is not a dead short. There is impedance involved.

[rockman96]

Since no one has asked and you didn't really said and people are just giving random answers without knowing,

Yep, beginning with you.

[Tattooo]

Yep, beginning with you.

Or you....... Do you know the answer to my question???