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Did you have heated gear on at that time? Another member here had the same exact thing happen but found it was caused by his heated gear turning on and off constantly.
Mine turned out to be wireless controller, when potentiometer(s) were in certain position I would have voltage fluctuations, but mine weren't that drastic (11V to 15) only about ą 0.5-1V
I have not proven it yet, by replacing the bolt and running it,
BUT, Im 99.99999 % sure I found the problem,
thanks to all of you and the advice from this post!
AND, Im sorry & glad to say I just learned a valuable lesson.
The image is of my positive battery bolt and the black stuff on the bottom of the head of the bolt is what is left of a star washer I had put on it because it had come lose sometime in the past.
Obviously, the star washer could not take the heat or more correctly the current! And this is pretty much beyond a doubt the cause of the problem I saw.
Note to self never put a star washer on a battery or electrical connection again.
I am replacing the bolts with a slightly longer 304 Stainless steel battery bolt with washer and lock washer pre assembled so to speak,
what I order are battery terminal bolts! So, I hope to say goodbye to the battery terminal bolts going lose again.
Thanks for getting back. My 04 Softail use to get loose at the negative terminal.
Knew it was from movement. The battery then was a Harley branded one. There was no clamp of sorts to tie it down. Just sat in oil tank on a formed rubber pad.
So I snuged it with 1/4" thick scrap of grooved isolation rubber.
It has a leather Corbin seat on the bike. Just happened to notice years later cleaning out the garage that the original seat had a bumper button on it to snubb battery.
If you have any movement, make sure it's not tugging on cables.
Electricity can do strange things to loose connections. I have seen no threads on bolts and in the terminals of those NGK sparkplug that screw off for spring type of application.
If you use NGK with the option that requires the terminals on, snug the aluminum terminals with pliers.
Last edited by Jackie Paper; Feb 25, 2025 at 05:34 AM.
Checking battery connections is part of regular maintenance for me.
With the plastic cover over the battery, you have access to the negative screw, but not the positive.
I drilled a small hole directly above the positive post screw to access it with a screwdriver.
Checking battery connections is part of regular maintenance for me.
With the plastic cover over the battery, you have access to the negative screw, but not the positive.
I drilled a small hole directly above the positive post screw to access it with a screwdriver.
It sure seems like a PIA to get at the battery on these new bikes. I have not removed mine, almost need the manual to find it. Drilling hole is interesting idea..
It sure seems like a PIA to get at the battery on these new bikes. I have not removed mine, almost need the manual to find it. Drilling hole is interesting idea..
Did it on my 09 & 17. I use a screwdriver with a hex for a wrench.
I had this problem with my 06 roadglide, too. Did all of the preliminary checks: battery, terminals, alternator output, gauge connections, etc. The gauge kept acting weird, so I installed a new gauge. That fixed it.
New batteries come with bolts.
Some batteries bring spacers for cable alignment at terminals.
I have seen folks that have reused old bolts on the new battery.
The old bolts were longer and bottomed too soon.
That made bolt tight but cable was not compressed causing arcing and charging problems.
Suggestion, for both ends of the battery cables, may or may not help. For years I had to tighten the battery cables at least once a year. Finally noticed with the final tightening, as the bolt turned the cable shifted in the same direction the bolt was turning. This put a constant pressure from the cable to loosen the bolt over time. I now push the cable as far as it will go in the opposite direction and tighten the bolt. When released, the cable tries to "spring" back, now in the direction to keep the bolt tight. Battery bolts don't seem to get loose as frequently now. I hope this explanation isn't confusing.
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