Battery won't stay charged - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 13 (permalink) Old 07-31-2015, 12:43 PM Thread Starter
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Angry Battery won't stay charged

Hello, I am new to this forum and this is my first post. I have a 1985 VN700 that runs great, however the battery refuses to stay charged after a couple rides. I know the battery is fully charged, because I charge it on a trickle charger and test it with a multimeter. When fully charged, the voltage reads around 12.5 volts.

I tested to see if the stator sends any power to the battery yesterday, and the voltage jumps up slightly (between .3-.5 volts) when I pull back on the throttle. I went for a 60 mile ride and it had no problems. I got back, shut it off, and ten minutes later tried to start it again to get it into the garage, and the starter wouldn't even turn over. This has happened many times over the past few months, and I have to take the battery out and recharge it inside. A couple of times, the bike died on me while riding also, which is initially what got me to believe that the stator might be bad (and knowing that stators for these kinds of bikes tend to go bad), but obviously it sends some power to the battery. My next thing to check is going to be the voltage regulator, I read that also can go bad. Could the stator still work partially (showing a spike in voltage), but just not keep up with the electrical demands of the bike? Can you guys think of anything else that I could check that might be the culprit?

Thank you very much
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post #2 of 13 (permalink) Old 07-31-2015, 12:45 PM
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Originally Posted by VN750Rider/Jerry View Post
It's really easy.

1. With the bike off disconnect the 3 bullet connectors coming from the stator.

2. Set your meter on ohms

3. Touch one lead from the meter to the engine case. I used the rear manifold to avoid paint getting in the way. It does not matter which lead goes where. With a lead touching the engine, take the other lead and touch each of the 3 yellow wires in turn. Make sure they are the wires coming from the stator, not the wires coming from the R/R. You should get no continuity between any of the wires and the engine. If you do, your stator is shot. If not, move onto the next test.

4. Set your meter to VAC. Start the engine and rev it to 3000 rpm. Now check the AC volts between all 3 of the yellow wires, 2 at the time. Do not let the wires touch each other or ground. You should get high 40 to low 50 AC volts at each wire on a stock stator. If you do, your stator is good.

5. Now with a fully charged battery showing 13.xx volts with the engine off, start the engine and rev it to 3000. With the meter set to DC volts, and the leads connected to the battery terminals, you should get over 14 volts. If you do, everything is ok. If the voltage does not go up, or drops (the lights draw power from the battery, and can make the voltage drop down to around 11 volts if the system is not charging) the system is not charging, so it's probably the regular.
Stolen from Jerry since slim's guide is no longer available for whatever reason.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350

Last edited by thtanner; 07-31-2015 at 12:52 PM.
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post #3 of 13 (permalink) Old 07-31-2015, 01:06 PM
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What is the battery voltage when it won't crank? Is the battery actually dead?

Just mentioning this, in case .... There can be a fault in the Junction Box that prevents the start button from working and it can be intermittent. (this fault is easily bypassed)

Doesn't sound like it's putting out enough charge though, there should be a bit more than .5v rise when revved.

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post #4 of 13 (permalink) Old 07-31-2015, 02:08 PM
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You just need to clean your ignition switch. Little black puck under your key. I guarantee it.

Just be careful not to lose the ball bearing and the springs. They are small. Clean the contacts to shinny and stretch the little springs ever so slightly. If you break the tabs on the puck just use super glu and a zip tie to sinch it back tight. Your stator is probably fine.

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post #5 of 13 (permalink) Old 07-31-2015, 02:41 PM Thread Starter
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Quote:
Originally Posted by Spockster View Post
What is the battery voltage when it won't crank? Is the battery actually dead?

Just mentioning this, in case .... There can be a fault in the Junction Box that prevents the start button from working and it can be intermittent. (this fault is easily bypassed)

Doesn't sound like it's putting out enough charge though, there should be a bit more than .5v rise when revved.
I will check the battery this afternoon when I get off work before I throw it on the charger. As for the ignition switch, I will clean it out as best I can.
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post #6 of 13 (permalink) Old 07-31-2015, 09:41 PM Thread Starter
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Ok so the battery is reading 11.5 volts. Won't crank the starter. And I have another issue that developed during yesterday's ride. My headlight went out. I thought it was the bulb, because all the other lights work, so I took the headlight assembly apart and replaced the bulb with a new one, and it still nothing. I used my voltmeter to test the harness that connects to the bulb, and I'm getting 0.15 volts. I have no idea what it should read, and the Clymers manual doesn't seem to offer any input, but some electricity is getting to it (obviously not enough to power the bulb). I checked all the wires to see if anything came loose, and checked all the fuses on the left side of the battery and everything seems to be in order. I am much better with mechanical aspects of vehicles than electrical, and this is quickly turning into a nightmare for me. Any input?

Last edited by MikeAD247; 07-31-2015 at 10:05 PM. Reason: add stuff
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post #7 of 13 (permalink) Old 08-01-2015, 12:45 AM
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Originally Posted by thtanner View Post
Stolen from Jerry since slim's guide is no longer available for whatever reason.
My Guide is available.. you just have to email me to get it...
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post #8 of 13 (permalink) Old 08-01-2015, 12:54 AM
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Originally Posted by MikeAD247 View Post
Ok so the battery is reading 11.5 volts. Won't crank the starter. And I have another issue that developed during yesterday's ride. My headlight went out. I thought it was the bulb, because all the other lights work, so I took the headlight assembly apart and replaced the bulb with a new one, and it still nothing. I used my voltmeter to test the harness that connects to the bulb, and I'm getting 0.15 volts. I have no idea what it should read, and the Clymers manual doesn't seem to offer any input, but some electricity is getting to it (obviously not enough to power the bulb). I checked all the wires to see if anything came loose, and checked all the fuses on the left side of the battery and everything seems to be in order. I am much better with mechanical aspects of vehicles than electrical, and this is quickly turning into a nightmare for me. Any input?
First try switching the three yellow bullet connector wires around for the Stator.. If one leg is burnt out and that leg is going to the Fuse box, then the headlight relay won't energize, not allowing 12 volts to go to the headlight. If that doesn't work, then you either have a blown fuse, or a bad relay inside the fuse box... last possibility with the headlight is a bad reserve lighting unit.
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post #9 of 13 (permalink) Old 08-04-2015, 10:51 AM Thread Starter
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I recharged the battery and the new bulb works. It ended up being a bad r/r, I ordered a new one and it should come Wednesday. Hopefully that will be the end of my electrical issues this summer
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post #10 of 13 (permalink) Old 08-06-2015, 10:01 AM Thread Starter
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So now I have another question. Should the battery be charging while the bike is idling? After putting in the new regulator, I see a slight voltage drain in the battery while the bike is idling, but it goes up if I rev it. I've read in a couple places that at idle, the battery isn't really charging, you have to ride it around for that to happen.
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