Troubleshooting Battery drain possibly Alternator/Regulator/Stator

[Traeden]

Hi,
So i just recently bought a 2000 monster m900ie. I'm troubleshooting my first problem. I went out to start it and it turned over a few times then started, eventually it wouldnt start. i'll spare you all the details of bad dealership mechanics. Here's what i know who didn't fix shit.

I have a brand new battery. It doesn't lose voltage when the bike is off but when i ride it loses voltage. When the bike is running its only producing 11.5 volts at the battery terminals. From everything i've read it suggests there's something wrong with the Alternator, Regulator/Rectifier and or stator. How do i check the regulator/ rectifier? How do i test the stator? how do i test the alternator? is there anything else that might be wrong?

Thanks

[Slide Panda]

Hi, good one you for reading the suggested rules and posting your first post here. But this is just the social introduction section. You've got a tech question - so you should just copy the content and fire up a thread in there. It'll get a lot more attention there than in this section.

But, it seems like your charging system is on the way out. You've already done one of the biggest fact finding test by testing the voltage while running. It should be putting out over 13 volts while running - though I don't recall the exact figures.

[ducpainter]

13.5-14.5 while running

[Howie]

This is easier than me writing out the whole nine yards.

http://www.electrosport.com/technical-resources/diagnosis-center/fault-finding-guide

Cheap fixes first.  There are wires coming out of the left side engine side cover.  Follow them to the right side and you will see three relatively heavy yellow wires going into a cheesy connector.  The other side goes to the voltage regulator.  Make sure the connection is clean and tight with no signs of overheating.  Also check the 40 amp fuse next to the battery.  This fuse is for the voltage regulator.  Bad fuse = no charging.  Check the battery connections and the ground by the oil breather.  Then check stator output, diodes, etc.

[Traeden]

Thank you fellas,

Howie i read your previous posting to someone else about testing the 3 phase yellow wires etc. you seem like a good resource for any questions i might have in the future so sorry if i bother you but thats the price you pay for being smart with a specific knowledge set. I'll check out this fault finding pdf and see what i can find.

Thanks  Again

[Michael]

My battery light came on and then the next time I tried to start my bike the battery was dead. I got it charged and then hooked up my multimeter. The battery was fine, but no charge was getting to it.

I left my multimeter connected to the battery before trying to diagnose the regulator and stator, and while taking off the straps that hold the wires to the regulator I noticed the volts jump.

At closer inspection, the two yellow wires were exposed and touching. The wire coating seemed to be melted away (see image below). As soon as I separated them the battery was getting a good charge.

I wrapped them in electrical tape, and then slit a small rubber heater hose down the center to put on as extra insulation from the heat of the engine.

Here you can see the exposed wires (two yellow wires in the center of the image) before I put on the electrical tape and hose:

[Traeden]

Forgot to come on and close the case. It ended up that my rear brake light was permanently stuck in the on position which was causing a drain on my battery when the bike was on. Figured it all out when I had to get it passed for safety haha. Thanks for all the input and I learned a lot about the electrical charging system as a result

[Howley]

If your multimeter is reading only 11.5V while running the brake light was not the problem. It's either your regulator or your stator.

[Howie]

I agree with Howley.  The results for your stuck brake light should be driver confusion and possibly a melting lens.  You are undercharging.

[Traeden]

after that was fixed the voltage was fine and I never experience any battery drain. the 11.5 voltage reading was before I fixed the brake light. it returned to its 14.5ish after the fix while running