Charging issue - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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Where does this wire go?
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post #1 of 28 (permalink) Old 06-11-2019, 07:51 PM Thread Starter
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Charging issue

Hello, working on a friends bike. His bike kept dying with a dead battery on side of road going to work. It is a 1993 Vulcan 750.
Him and his friend diagnosed it without me as the regulator and replaced that to no success. They than diagnosed it as a stator there enters my issue.
The bike gets dropped off to me and after three times of pulling the motor (I’m a pro now it’s out in 1.5 hours) it’s back together and running (different leaks that appeared were reason for pulling repeatedly).
So I do the stator rewire the burned harness bullet connectors and start it up. The battery is new and fully charged. I got 12.4 volts at idle and 12.9 at ~3100. Not good enough to my understanding.
I read the forum and pulled the headlight fuse. I now at 13.2 at 1500 rpm (yay) but when I rev it to 3000 it drops to 13 volts. Is there any thing else to do or check? I can’t figure out why it is behaving like this. Wire connections appear to be clean.
I haven’t tested the stator or the regulator as they were new and do appear to be working to some capacity.
Thank you
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post #2 of 28 (permalink) Old 06-12-2019, 11:20 AM
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Have to start with stator testing, ... What are the AC volts?

If that checks ok, test the R/R, next I suppose I would think about the Blue Wire and Two-Wire mods to take 2/3 of the JB out of the question.

Any extra lights added to the headlight circuit?

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post #3 of 28 (permalink) Old 06-12-2019, 01:06 PM Thread Starter
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I will have to check the stator tomorrow. I know it’s not the best to skip but didn’t do it (the wires are impossible to get to with my hand size so need help). There are no accessories on the bike other than a hook up for tender (not currently on the bike anyways).
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post #4 of 28 (permalink) Old 06-14-2019, 08:44 PM Thread Starter
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I checked the stator everything is right on spec. The regulator I believe is good (I’m not getting infinity but getting even numbers across terminals (6.5 m ohms). Would this be sufficient? I would think if it was a bad regulator all the leads would not be the same number.
So I cleaned the connections I had to deal with all are clean good and tight. The bike goes up right to about 13 volts at 1500 rpm than flat lines to even slightly drops when revved to 3000.
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post #5 of 28 (permalink) Old 06-14-2019, 09:24 PM Thread Starter
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Alright I’ve checked everything and read other forums. Should I just take it for a ride and see what it does once warm/hot. I mean at the end of day 13 volts is charging either way.
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post #6 of 28 (permalink) Old 06-14-2019, 09:24 PM
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That is not high enough to charge the battery, you still have a problem.

When you checked the stator and R/R what checks did you do?

Stator should look like three wires joined together at the far end with no connection to ground using an ohmmeter. There should be AC voltage of at least 40 and maybe as high as 70 v between each pair of the three wires when running and the R/R is disconnected.

R/R is harder to check , simply measuring ohms across terminals is not really adequate, if you get the AC volts in from the stator above and don't get ~14.5 volts out it is the R/R thats dodgy.

Make sure the R/R sense terminal is connected directly to the battery and not through the JB or any other place. Make sure the R/R is grounded properly and remake all the two part connectors jst make sure they are getting good contact

'99 Vulcan "Victoria"
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post #7 of 28 (permalink) Old 06-14-2019, 10:33 PM Thread Starter
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Took it for a 5 mile ride came back 13 volts at 1500 and 13.3 at 3000. So it is charging
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post #8 of 28 (permalink) Old 06-15-2019, 07:49 AM Thread Starter
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For the stator I did the 3 wire check for resistance and got infinity. For the ac voltage test at idle I got ~25(don’t remember exactly) at 3000 rpm all three leads read 58.
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post #9 of 28 (permalink) Old 06-15-2019, 07:51 AM Thread Starter
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So your saying wire directly from the regulator to the battery For the battery terminal (I have an aprilia that I bought that was repaired like this I didn’t notice the extra wires until I changed the battery the next spring).
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post #10 of 28 (permalink) Old 06-15-2019, 08:51 AM
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The R/R should have 6 connections, three go to the yellow stator wires in any order, thats the power input.
There will be a 12v (nominal) out and a ground. Get these connected as close as you can to the battery with as few joints in the way as possible.
Then there is a "sense" connection, this provides the feedback on the actual voltage in the system. On a stock bike this takes a long journey that can have voltage drops due to poor connections. Make this connection as close as you can to the battery + terminal if not actually on it.

For a lead acid battery "The actual resting voltage, or the voltage a battery will settle at 12-24 hours after being removed from the charger, is closer to 2.1 volts per cell, or about 6.4 volts for a 6v battery, and 12.7 volts for a 12v battery. These numbers assume 100% healthy cells, and may vary a bit lower for older batteries."

So your 13v is not enough to charge the battery, you need to see 14.5v or better.

'99 Vulcan "Victoria"
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