Author Topic: Mystery electrical problem,help (Read 33902 times)

Kchop · « **on:** July 25, 2024, 12:15:54 PM »

Hello, my first time here, hope I'm in the correct forum.

I have a 1993 k75s. Low miles, battery about a year old. Did a 600 mile ride 5 months ago, no problems.
A week ago I'm coming back in from a ride and bike dies suddenly while riding. Turn the ignition switch to second position , don't hear the fuel pump...before I panic I look at the fuse for the heck of it, its blown. I replace (feeling good about myself) more riding.

Yesterday I ride to store (couple of miles) turn bike off, coming back out battery totally dead. I have someone run me out a portable charger, JNC 660. Put it on the terminals and with the kill switch in OFF position AND the
Ignition switch in absolute OFF position, bike is trying to start?? Is that normal??l (never used the portable charger before). I turn key to "on" position, kill switch to run..bike starts . Remove neg terminal clamp , bike dies.
Was thinking alternator...now not so sure.

Any help appreciated,

Thank you

Ingo · « **Reply #1 on:** July 25, 2024, 01:45:09 PM »

Alternator, right. Battery discharged, starter relay "locks" up in engaged position, drains batt. Alternator is not generating power, otherwise she'd keep running after successful start. You could remove batery and charge, then re-install to get bike home... BTDT...

Kchop · « **Reply #2 on:** July 25, 2024, 04:36:15 PM »

Thanks for the answer. freaked me out when the neg sparked and bike wanted to turn over, lol.

Chaos · « **Reply #3 on:** July 25, 2024, 10:10:35 PM »

pretty common, low battery can cause the starter relay contacts to weld themselves together. Usually you can bang on the relay to get them to open again. Putting in a fresh battery will just make it crank without you telling it to.

Kchop · « **Reply #4 on:** July 26, 2024, 10:10:12 AM »

Hey, update on k75: Thanks to Chaos and Ingo.. you were correct. Charged battery overnight with NOCO charger...started this morning.

Couple of questions: trying to hunt down video on alternator replacement for this model?

I see replacement alternators with wide range of prices. Anyone have suggestions for best part supplier? If there's a better forum for that question please let me know.

Thanks

Laitch · « **Reply #5 on:** July 26, 2024, 10:41:12 AM »

Quote from: Kchop on July 26, 2024, 10:10:12 AM

Anyone have suggestions for best part supplier? If there's a better forum for that question please let me know.

Euro Motoelectrics.

Martin · « **Reply #6 on:** July 26, 2024, 04:47:23 PM »

Check the brush rectifier pack before you buy a complete alternator. Worn brushes and/or a faulty rectifier could cause your problem. They can be replaced easily without removing the alternator. Used alternators can also be found a lot cheaper.
Regards Martin.

Kchop · « **Reply #7 on:** July 26, 2024, 05:10:58 PM »

How does one identify if they are faulty? I assume the brushes would look worn to the eye? How does one evaluate the rectifier pack?
Sorry for the basic questions, just starting to work on bike by myself.

Kchop · « **Reply #8 on:** July 26, 2024, 05:23:13 PM »

If I remove side cover this can be accessed and see if its worn correct?

Ingo · « **Reply #9 on:** July 26, 2024, 05:34:12 PM »

Not exactly. You can probably get to the regulator without removing complete alternator. The brushes are integral to the regulator. There's a wear limit, meaning a certain minimal length of brushes. Not sure about the number right now. The rectifier can be replaced (had to do it on mine) but requires removal and disassembly of alternator, some soldering, also. Search here on forum, there's tons of info on this.
In fact, there's a write-up from yours truly on exactly this...

Ingo · « **Reply #10 on:** July 26, 2024, 05:55:49 PM »

Check out this one, as well as other posts, also important is the "monkey nutz"...
https://www.motobrick.com/index.php?topic=15675.msg139156#msg139156

Kchop · « **Reply #11 on:** July 26, 2024, 06:54:38 PM »

Thank you, appreciate it.
One more thing. Trying to find out before I dive in whether its a 32 A or 50A alternator. Bike is a 93, but running a VIN check, its manufactured in 92. Of course early 93 is 32A, later 93 is 50A. Any insight there?

Laitch · « **Reply #12 on:** July 26, 2024, 07:18:16 PM »

Before you dive in, test the alternator to determine its output. All this hoopla may have just been caused by a battery that couldn't hold a charge regardless of what the alternator was doing.

32 Amp

50 Amp

Laitch · « **Reply #13 on:** July 26, 2024, 07:23:43 PM »

You'll find the answer to your regulator brush question in the same Chilton chapter from which you copied the parts illustration you posted.
new brushes are 10mm in length, brushes due for replacement are ≤5mm in length.

Kchop · « **Reply #14 on:** July 27, 2024, 02:12:24 PM »

ok, thank you for the test suggestion.
Took a voltmeter, set at 20:
Battery 12.41 no key in ignition
Battery 11.87 Key in on position / no start
Battery 11.69 on initial start / Charge light on
Battery 12.32 rev to 1500rpm/ charge light goes off
Battery 13.27 @ 2000 rpm

Shall I interpret this as the alternator doing its job? Could it just be a bad battery that's only a year old??

Ingo · « **Reply #15 on:** July 27, 2024, 03:19:55 PM »

Could be battery, but my brick runs at 14.4 V...
Seems to me that you're not getting proper voltage.
Let some more people chime in here...

frankenduck · « **Reply #16 on:** July 27, 2024, 03:39:43 PM »

The factory 32A voltage regulator is 14V.

Kchop · « **Reply #17 on:** July 27, 2024, 04:29:06 PM »

So, that would point to the voltage regulator/brush assembly in the alternator yes?

Ingo · « **Reply #18 on:** July 27, 2024, 06:58:24 PM »

Regulator is a wear part, might as well buy one and try, then you know brushes are good plus it MIGHT solve the issue.

Laitch · « **Reply #19 on:** July 27, 2024, 07:13:09 PM »

Quote from: Kchop on July 27, 2024, 02:12:24 PM

ok, thank you for the test suggestion.
Took a voltmeter, set at 20:
Battery 12.41 no key in ignition
Shall I interpret this as the alternator doing its job? Could it just be a bad battery that's only a year old??

If your battery was charged overnight with a slow charger and only tested at 12.4V, that is not an optimal result. Try it again to see what you get.

Which amperage is your alternator? The 32A's regulator is easily removed so you can measure the brushes. You need to remove 50A's rear cover to access it.

Kchop · « **Reply #20 on:** July 27, 2024, 07:25:25 PM »

Battery was charged with a slow charger, overnight.
I'll try agin tonight.

32A Alternator. I'll remove and look at the brushes and do what Ingo says, cuz that part won't hurt that much....

Kchop · « **Reply #21 on:** July 27, 2024, 07:29:18 PM »

What is your battery of choice btw... don't seem to be having luck with the odyssey agm so much.

frankenduck · « **Reply #22 on:** July 27, 2024, 07:48:43 PM »

Big battery:

https://www.amazon.com/gp/product/B07G8GHCFG

"Half" battery:

https://www.amazon.com/gp/product/B074VFKRKL

Kchop · « **Reply #23 on:** July 28, 2024, 11:07:37 AM »

Charged overnight with slow NOCO charger.
Battery: 12.59 this morning with absolutely no load.

Kchop · « **Reply #24 on:** July 29, 2024, 10:03:54 AM »

Can someone comment on what a "healthy" battery volts should be after a nights worth of charging. Getting conflicting info. I'm going to change out the voltage regulator anyway, would be nice not to change both parts right now. I checked the purchase date of the Odyssey battery: a little over 2 years old.

Thanks

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Author Topic: Mystery electrical problem,help (Read 33902 times)