Battery dies without ignition on

[jurgenkoppen]

Hi all,

I am new on this forum and with my 78 xs650E.
My issue is that the battery dies when parked. There is a voltage drain of about 0.1V and I suspect the rectifier. The manual I find cryptic on the test procedure.
Can anybody here direct me to a straight up analysis method to trace the problem?
Also if it is the rectifier or alternator, are there some solid state aftermarket components to replace the 32 year old technology with something reliable?
Thanks, Jürgen

 

[kent_in_kc]

Hello Jurgen. I would first disconnect both battery cables and see if the battery dies. If so, you have a short in the battery. Otherwise, I would remove fuses one at a time and watch to see if the drain stops, thus you know what is causing it.

Yes, there are solid state alternators, so-called permanent magnet alternators, that you can install. 650Central.com sells the SparkX for example. I have one and am happy with it.

 

[inxs]

- welcome...the rectifier is basically 3 pairs of diodes, 1 pair for each white cable[+/-], these pass current in 1 direction only, when testing test in both directions, if open in both directions throw it away... try curlys guide for alternator testing and look through pamco stuff for replacement rec-reg

 

[jurgenkoppen]

Thank you Kent and Inxs,

I ran some tests.
The voltage leak is on the main fuse circuit, pointing to charging system.
Regulator checked out OK, all ohm readings to spec.
Rectifier came in with 500ohms over each diode in one direction, instead of the 75-150 ohms as in the Clymer manual.
Alternator was OK at 1ohm across the white wires,but the stator housing to white wire test showed 20ohms each instead of infinity as per manual.
The rotor winding test slip ring to slip ring was 2 ohms instead of 5-7 ohms.
What are you making of these results????
What should I do, replace or fix here?

 

[Tz250racer]

Get a voltage meter from Radio shack and then check your voltage at 3000 rpm.If you get 14 volts then your charging system is ok.If you get 12volts then your problem could be a bad battery,worn alternator brushes,rect-reg-bad alternator winding.Check all the connectors for good contact.I hope you have a service manual.Check all those things before you start spending money on parts.Regulator has an adjustable voltage output screw inside the body.Service manual will tell you how to test all those parts.Have fun.

 

[jurgenkoppen]

TZ, thanks you.
Re:If you get 12volts then your problem could be a bad battery,worn alternator brushes,rect-reg-bad alternator winding
Yes, I have a Clymer manual, I refered to it to get the correct ohm readings.
The point is that I need to know which one of the components are the most likely culprit in light of my test results.....Which were:
Rectifier came in with 500ohms over each diode in one direction, instead of the 75-150 ohms as in the Clymer manual.
Alternator was OK at 1ohm across the white wires,but the stator housing to white wire test showed 20ohms each instead of infinity as per manual.
The rotor winding test slip ring to slip ring was 2 ohms instead of 5-7 ohms.

Anybody know how to interpred these readings?

 

[jurgenkoppen]

TZ, thanks you.
Re:If you get 12volts then your problem could be a bad battery,worn alternator brushes,rect-reg-bad alternator winding
Yes, I have a Clymer manual, I refered to it to get the correct ohm readings.
The point is that I need to know which one of the components are the most likely culprit in light of my test results.....Which were:
Rectifier came in with 500ohms over each diode in one direction, instead of the 75-150 ohms as in the Clymer manual.
Alternator was OK at 1ohm across the white wires,but the stator housing to white wire test showed 20ohms each instead of infinity as per manual.
The rotor winding test slip ring to slip ring was 2 ohms instead of 5-7 ohms.

Anybody know how to interpret these readings?

 

[XSLeo]

When you test the stator you need to unplug the yellow wire. It will ground through the safety relay and show about 20 ohms.
The 2 ohms on your rotor is low. Being that low your battery isn't charging fully. And will draw the battery down quicker because it draws more current to produce less electricity.
How old is the battery? It may be bad. Take it to someplace that sells batteries, they can load test it for you. If the battery is bad it can discharge it self.

 

[jurgenkoppen]

Thanks Leo for the yellow wire tip, I was not aware of this.(Nor the Clymer mention it)
I just ran the test again,yellow disconnected, an voilá, I do have infinite resistance, so the stator checks OK.
The battery age I am not sure off, but it is holding charge on its own when not in the bike system, I checked that.

The main problem remains that there is a 0.8-1.0 V current flow to ground: when I disconnect the negative terminal from the frame, and put my Voltmeter between the frame and the negative terminal.
That flow stops when I disconnected the rectifier, which tested at 500ohms black to white one way, instead the 75-150ohms as per spec.
I guess the rectifier is the culprit.
The rotor at 2 ohms over the slip rings (spec 5-7 ohms) may need replacement as well then?
Could one faulty component have damaged the other?
Please help me decide where to drop the money. Thanks, Jürgen

 

[XSLeo]

I might still get the battery load tested. Most places that sell batteries will do it for free.
On your recifier 500 ohms is about what I get on my 75 recifier. My meter has a diode test function. I get 500 reading one way and infinite the other. On the ohms scale I get a 200 ohm reading. I think your rectifer may be ok as long as you get the 500 ohe way and infinite the other.
I don't know how to post links, Pamcopete has developed a way to replace the rectifier with parts from Radio Shack. If you do a search here or look on 650 Garage USA he explains it. In the electrical section under $6.58 rectifier.
Your rotor with just 2 ohms is bad. Your battery is not being charged. This maybe the problem, not getting a full charge, it goes dead quickly.

 

[Tz250racer]

Do the voltage check before you start buying parts.With the bike running at about 2500 rpm check the voltage on the battery.You should get 13.5-14v.If you get that reading the the charging system is working.If the battery dies then buy a Parts Unlimited battery.If still got the problem then disconnect the starter and see.A bad starter could drain your battery over short time.I removed mine.Garbage...really.