Hey all, long time lurker, first time poster.

I've had some problems with my battery not keeping a charge and I want to make sure I'm not doing anything dumb- I have a'15 FXDB btw. Its happened a few times, my motor wouldn't turn over, so I put my battery on the trickle charger, ride for a few days with no problem, then get a progressively weaker start to the point where it wouldn't turn over again. I finally bought a multimeter and got some readings- 12.6v right off of the trickle charger, then 12.3 after turning the engine over a few times.

I also revved the engine to see if it was getting a good charging input from the generator/stator and it went up to around 14.3v. So it sounds to me like the issue is the battery cells are shot, right? I took it to Autozone and the guy there said it load tested fine. I'm pretty stumped right about now.

 

Watch/check for an intermittent Voltage Regulator output, or a bad connection in the charging circuit.

 

At the top of this section we have a couple of Stickies on how to check your charging system. Read and follow them through, which should help you pinpoint the problem. You're doing the right thing to diagnose first, before buying anything!

Your bike is quite recent, so some of the causes of problems, due to age, shouldn't affect your bike, but do check both ends of both main battery cables, to make sure they are clean and tight.

 

After reading through the sticky, I just want to make sure I'm troubleshooting the right thing. To test the Voltage Regulator, put the black lead of the multimeter on battery ground, and the red lead on the male pins of the voltage regulator on the side that connects to the stator? ( I circled it in the pic in case my description sucks) I did that and measured the same as the battery voltage (which is now 12.25v after sitting connected to the bike overnight from 12.35).

I checked the terminals at the connection point to the battery and they're clean and clear of grime/corrosion so I'm thinking I can rule that out.

Thanks for your patience, help, and quick replies- electrical issues aren't my strong point.

 

You've already diagnosed your problem! At 12.6 volts, you battery is more than 25% discharged. I'm assuming that the 12.3 reading is AFTER cranking the bike over, not during? At 12.3 volts, your battery is all but ready to die. At 14.3 volts, your charging system is working properly! I'd venture a guess that your volts drop WAY more off DURING cranking!

As for the guy at Autozone, with these readings he doesn't know what he is talking about!!!

 

sorry

 

where did you come from?
Another update?
Wheres the first story?
Are yon sure you're responding the THIS thread?

THIS one is 6 years old!

 

Sorry, I have no idea, why my post ended up on this topic, I'm discussing my problem elsewhere, I didn't even know about the topic, and I only saw that it existed when you responded, and then I received the notification in my email now . Sorry about that, but I actually don't know how my answer ended up here.

 

all good.....sometimes the OTHER POSTS LIKE THIS ONE at the bottom of the pages take over.......

 

Old thread. But 12.7 should be 100%. So 12.6 will start a bike just fine. I ran all year on what was 12.3 last winter. Check your manual or the manufacturer of battery to make sure same, but in my experience 12.7 is 100%, Though a 1/10 does count for a lot. So you need a decent meter.

I think if you look 12.6 is probably going to be a little higher than 75%, and regardless will start a bike fine.