Every ******** year with these batteries.
Seasoned HDF Member
Joined: Apr 2011
Posts: 6,185
Likes: 2,134
From: W. Texas
Just throwing at the wall. I worked at a GM dealership for a number of years.
Have seen a number of modules that would intermittently power up themselves.
There was an Amp in a Cadillac I remember the best. The fluke meter we had could record Max and Min.
We left it hooked up over the weekend , came in Monday morning. to a dead battery.
The meter had recorded a max reading of almost 4 amps Put charger on battery for awhile. This was 10-12 years ago.
A little guess work and some luck I put an Amp in it. No more dead battery.
Good Luck Sir WP
Have seen a number of modules that would intermittently power up themselves.
There was an Amp in a Cadillac I remember the best. The fluke meter we had could record Max and Min.
We left it hooked up over the weekend , came in Monday morning. to a dead battery.
The meter had recorded a max reading of almost 4 amps Put charger on battery for awhile. This was 10-12 years ago.
A little guess work and some luck I put an Amp in it. No more dead battery.
Good Luck Sir WP
Seasoned HDF Member
Joined: Feb 2016
Posts: 8,010
Likes: 6,907
From: NC
I like a good discussion.. Use google AI and you can go look at the source. IMO this one is not to far off and the truth is that you do have to charge to a higher voltage to get full charge if it's cold. Now on a vehicle, charging may not be temp compensated. I have an off grid solar/generator house system for 27 years (been grid tied for the last 8) and getting full charge on $5000 of batteries is important to battery life. I had a temp sensor fall off the battery during the winter and almost smoked the whole battery pack of 12 6 volt Trojan L16s..
Like I said the HD systems seem to be geared towards putting out 14.4 volts. I've seen higher but usually after some idiot adjusted the regulator on a 65 pan or 78 honda 750. I had a regulator fail on one bike and cook a LI battery. I've been working MCs since the 60s. The old analog voltmeters, like a Simpson 260, weren't that accurate.
One suggestion I'd make to the OP is to find a battery charger / maintainer that does temp compensate if the bike is stored below 60F.
Like I said the HD systems seem to be geared towards putting out 14.4 volts. I've seen higher but usually after some idiot adjusted the regulator on a 65 pan or 78 honda 750. I had a regulator fail on one bike and cook a LI battery. I've been working MCs since the 60s. The old analog voltmeters, like a Simpson 260, weren't that accurate.
One suggestion I'd make to the OP is to find a battery charger / maintainer that does temp compensate if the bike is stored below 60F.
I have not measured it at the battery yet, but my volt meter on my 2019 FLHTP reads over 14 volts. Probably about 14.5. I presume that those volt meters are displaying the line voltage and not at the battery voltage.
Grand HDF Member
Joined: Sep 2017
Posts: 3,847
Likes: 999
From: Southern Virginia
One suggestion I'd make to the OP is to find a battery charger / maintainer that does temp compensate if the bike is stored below 60F.
This is definitely a strange scenario. I can't remember if anyone has suggested checking current draw with the bike off? Since he rides it so much he might not notice a parasitic drain. Until I got a geezer glide I never used battery tenders because my bikes didn't sit long enough for the battery to get low. Still got several years out of those batteries. Shoot I would get over five years out of my shovelhead battery and sometimes it would sit while I would be riding my twinkie and I would have to kickstart it. Battery charged right up and kept on truckin.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,925
Likes: 8,027
From: poway
That makes me wonder, it was only in the past 25 years or so that my bikes were in a climate controlled location. Back when I was still running water batteries (I think that's all there was back then or I couldn't afford an AGM) my bikes stayed outside in the cold with no problems at all. It don't get super cold around here but it does get below freezing at night sometimes in the winter. Never had any issues unless I let those batteries get low on water.
This is definitely a strange scenario. I can't remember if anyone has suggested checking current draw with the bike off? Since he rides it so much he might not notice a parasitic drain. Until I got a geezer glide I never used battery tenders because my bikes didn't sit long enough for the battery to get low. Still got several years out of those batteries. Shoot I would get over five years out of my shovelhead battery and sometimes it would sit while I would be riding my twinkie and I would have to kickstart it. Battery charged right up and kept on truckin.
This is definitely a strange scenario. I can't remember if anyone has suggested checking current draw with the bike off? Since he rides it so much he might not notice a parasitic drain. Until I got a geezer glide I never used battery tenders because my bikes didn't sit long enough for the battery to get low. Still got several years out of those batteries. Shoot I would get over five years out of my shovelhead battery and sometimes it would sit while I would be riding my twinkie and I would have to kickstart it. Battery charged right up and kept on truckin.
Seasoned HDF Member
Joined: Aug 2006
Posts: 24,529
Likes: 30,849
From: Pennsylvania
If you have additional load on your motorcycle with extra lights, etc., 13.5 VDC charging voltage read at the line may not be enough to charge the battery fully. Even at 14.3/5 with all the lights and additional stuff will only be charging the battery with about 1.5 amps, reading voltage is not a good indicator of charging amps, which is necessary to charge a battery. Note: battery chargers, charge with amps, not voltage, although reading voltage can be an indicator of battery health.
1. You need to calculate the entire amperage usage of your bike.
2. Compare that to the amperage output of your stator.
3. You may want to put an amp meter on you charging system to see what it is doing.
If your stator is not putting out enough amperage to charge the battery then you may have found your issue.
Seasoned HDF Member
Joined: Feb 2016
Posts: 8,010
Likes: 6,907
From: NC
^^That is an important statement^^.
If you have additional load on your motorcycle with extra lights, etc., 13.5 VDC charging voltage read at the line may not be enough to charge the battery fully. Even at 14.3/5 with all the lights and additional stuff will only be charging the battery with about 1.5 amps, reading voltage is not a good indicator of charging amps, which is necessary to charge a battery. Note: battery chargers, charge with amps, not voltage, although reading voltage can be an indicator of battery health.
1. You need to calculate the entire amperage usage of your bike.
2. Compare that to the amperage output of your stator.
3. You may want to put an amp meter on you charging system to see what it is doing.
If your stator is not putting out enough amperage to charge the battery then you may have found your issue.
If you have additional load on your motorcycle with extra lights, etc., 13.5 VDC charging voltage read at the line may not be enough to charge the battery fully. Even at 14.3/5 with all the lights and additional stuff will only be charging the battery with about 1.5 amps, reading voltage is not a good indicator of charging amps, which is necessary to charge a battery. Note: battery chargers, charge with amps, not voltage, although reading voltage can be an indicator of battery health.
1. You need to calculate the entire amperage usage of your bike.
2. Compare that to the amperage output of your stator.
3. You may want to put an amp meter on you charging system to see what it is doing.
If your stator is not putting out enough amperage to charge the battery then you may have found your issue.
Seasoned HDF Member
Joined: Aug 2006
Posts: 24,529
Likes: 30,849
From: Pennsylvania
Question for the OP: When you replaced the Stator & Regulator, did you use OEM, Cycle Electric or some other manufacturer?
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,925
Likes: 8,027
From: poway
I have a 65 pan that has an amp meter. IMO the voltmeter is better. You get a better idea as to the charged state of the battery. You can sense how much current is going into the battery by looking at how fast the battery voltage recovers after starting.
I'm going to say something that some folks may not like. A LOT of info that AI has provided to me while searching has been completely wrong. I've been working with vehicles since the early eighties and have NEVER seen a charging system run much over 14 volts. I guess I should say a HEALTY charging system. As I mentioned before the engineers at a battery charger manufacturing plant I worked at in the early nineties found through extensive testing that charge voltages that high shortened the battery life.
In my job I drive all sorts of vehicles, vans, trucks, and forklifts. NEVER seen anything charge close to 15 volts. Maybe every situation I have been exposed to in the past several decades has been out of the norm, but I kinda doubt it. From what the OP is showing I don't think the problem is in the charging system unless it does go too high every now and then when he is out on the road. I wonder if it is possible that the battery box is somehow loose and shaking the battery more than normal?
Anyhow OP I wish you luck. Even on my bikes with heavily upgraded stereos in them I still get several years out of regular AGM batteries.
In my job I drive all sorts of vehicles, vans, trucks, and forklifts. NEVER seen anything charge close to 15 volts. Maybe every situation I have been exposed to in the past several decades has been out of the norm, but I kinda doubt it. From what the OP is showing I don't think the problem is in the charging system unless it does go too high every now and then when he is out on the road. I wonder if it is possible that the battery box is somehow loose and shaking the battery more than normal?
Anyhow OP I wish you luck. Even on my bikes with heavily upgraded stereos in them I still get several years out of regular AGM batteries.