Bad Alternator?

[ThreeAces97]

Have a 98 Standard, low miles. The Bike has pretty much sat for the last 4 years as I awaited hip replacement surgery.  Hip is great, but the bike isn't.   I have been researching alternator problems on our boards.  Here are my multi tester numbers.   Charged battery that sat out of the bike overnight  12.92 v.  Battery placed in bike and hooked up, then started.  Let bike warm up and then idle, 12.55 v.   RPM 2000, 12.25v, RPM 5000, 12.11v.   Took bike out for a local 20 minute ride, at idle I tested the battery again, 10.35v.  Shut the bike down, let it sit for 2 minutes, tried to start NOOOO Way.  Tested battery and was at 9.91v.   Everything I have read, says my alternator has gone south.  Here is my question, by taking out the alternator and replacing the brushes, along with all of the recommendations of cleaning (shoptalk page) dust, etc., will this fix my problem (if it was the alternator to begin with?  Thanks.

[Bone]

Read some more about bad batteries.  Have the battery load tested first.

[signart]

Bad bat.

[Chrisj CMA]

Also if the 55A fusable link is bad......alternator no workie

[vanagon40]

I'm agree with you on the bad alternator (assuming the fuses are all good).  You should get better than 12.2v at 500 rpm (more like 13.5 to 14.5).  Your battery could be toast as well, but I do not believe a battery that would hold a sufficient charge to start the bike at least once would show the voltages you are reporting if the alternator was working.

If the bike has low miles, it is likely not the brushes.  Most common cause of an alternator failure is a broken winding.  There is continuity test to determine whether that is the cause (search the forum or the shop manual), but it involves removing and disassembling the alternator.  Some members have been successful at finding the broken winding and repairing it.

Good luck.

[rhinor61]

First lets start off with :

Was the bike was running fine before it was parked for 4 years?

How many miles on the motorcycle?

The battery is how old?

Replace the battery with OEM spec.

once battery is replaced and wired properly, check all fuses and wiring connections including the ground to frame.

Now start bike and test battery voltage as described in prior post.

Lets do the basics before we become just parts changers.... BTW, the alternator is a PITA to change only to find the battery is junk...

let us know..

[ThreeAces97]

First lets start off with :
Was the bike was running fine before it was parked for 4 years?    Never a problem with the bike prior to last fall.   I had a bad hip and it hurt to transition from riding to feet on the ground).   So I only put a couple of hundred miles on the bike each year over the last 4, with last year being around 1200 miles.   Just before I put the bike away for the winter (live in NE Ohio), I went out on a 50-60 mile fall ride and the bike would start after about 1 1/2 hours of riding and stopping for a drink.   Had to push start the bike (never fun unless you have a good incline).   Rode bike home and put it away.   Most of my rides this year have been, start at home and return at home with no stopping.   No problems like last fall issue until this weekend.

How many miles on the motorcycle?    12k  I know, ridiculously low miles, between young kids and a lot of travel and golf, I don't ride like I used to.

The battery is how old?  OEM Yuasa purchased last May (2013), after I was cleared by surgeon to ride.

Replace the battery with OEM spec. 

once battery is replaced and wired properly, check all fuses and wiring connections including the ground to frame.

Now start bike and test battery voltage as described in prior post.

Lets do the basics before we become just parts changers.... BTW, the alternator is a PITA to change only to find the battery is junk...

let us know..   I will let you all know what happens.   Thanks.

[vanagon40]

Here is my old thread from 2008 in the old tech archives.  Explains all about the broken winding on the rotor.

[Gryphon Rider]

I agree with vanagon40.  Unless you have a bad connection, such as alternator or battery negative cables, the issue is the alternator.  It won't be brushes at such low miles, but is most likely a break in the winding on the rotor.  The simplest solution is to install a new alternator.  If so inclined, you or a rewind shop can try repairing the break, and maybe save a few bucks.

[signart]

I would make certain the battery is good and will hold a charge before anything. The simple test is charge the battery and just let it sit overnight off charge, see if it holds the charge. If it drops below 12V overnight the battery is bad. Batteries will sometimes take a charge, but won't hold.

[vanagon40]

I know everyone wants you to check or replace the battery, but I am not aware (and of course I could be wrong) of any battery that will hold a charge sufficient to start a Valkyrie, but then immediately drain the voltage output of a properly working alternator to less than 12.5 volts.  Again, I'm not saying you have a good battery, only that you have more problems than a bad battery.

[gordonv]

Also if the 55A fusable link is bad......alternator no workie

+1

If the alternator is working properly, but the fuse is blown ($1 part?), then the power from the alt is not getting to the battery.

You show EVERY sign of the alternator not charging the battery.

But the $100,000 question is "Why?". Don't start by replacing the alt. Start with a meter, and see if there is any output from the alternator AT the alternator.

[Flrider]

Have you checked the 55amp fuse?

[Rocketman]

I'm a big fan of checking the easy/cheap stuff first, even if it's not likely to fix the problem.  If it does, big win.  If it doesn't, you haven't lost much.
That being said, check the battery (don't just replace it just in case it's bad, actually check it), check the fuse, but I really think it's a broken winding.  Once the battery and fuse are ruled out, you could either pull the alternator apart and check it (brushes are easy to check, just a visual, while the winding is a bit more complicated, but not bad.  Check the manual for the procedure and ask back here if you don't find it); or you could just pay for a repair/replacement.  MARS in Indiana has done great work for me, and I trust his rebuilds more than I trust originals from Honda.

Mark

[Radman]

Also if the 55A fusable link is bad......alternator no workie

+1

If the alternator is working properly, but the fuse is blown ($1 part?), then the power from the alt is not getting to the battery.

You show EVERY sign of the alternator not charging the battery.

But the $100,000 question is "Why?". Don't start by replacing the alt. Start with a meter, and see if there is any output from the alternator AT the alternator.

Hi Gordonv,

I'm currently having issues with alternator as well. 

After reading through this post I noticed you said "start with a meter, and see if there is any output from the alternator AT the alternator". 

I'm pretty much a novice at mechanical repairs...but did recently buy a volt meter for my current issue and verified the battery was ok...held charge overnight and read 12.93V 30 hours after taking it off the charger.  After starting the bike and keeping RPMs at 2500, am only getting 12.16V.  Alt fuse is intact.  So I'm now looking at replacing the alt. 

However, I am also wondering if I am having some grounding issues, so would the above test prove the alternator is working but I'm having grounding issues?  If so, how would I go about testing the alternator output at the alternator?

Any help you could provide would be greatly appreciated.

Thanks   

[F6BANGER]

Radman,

Put the red probe on the power output of the alternator and the black probe on any good ground (alternator case, motor, bolt) with engine running. You should get around 14v. If not, bad alt. 

[Rocketman]

Radman,

Put the red probe on the power output of the alternator and the black probe on any good ground (alternator case, motor, bolt) with engine running. You should get around 14v. If not, bad alt. 

To clarify:  You will probably need to bump up the revs a little bit from idle in order to get 14V.  Idle is going to be pretty low voltage, but hit 14V quickly as you run the rpms higher.

Mark

[ThreeAces97]

Just a note of thanks to everyone that offered their respective advice.   I put in the time and after doing the shop manuals charging system test(s) and inspections (Chapter 16), I was able to determine that the alternator was indeed the problem.  After careful removal of all necessary parts to get the alternator out, I was able to test the alternator cable and the Battery voltage input and charging lines.   I ordered the HITACHI LR140-718A (rareelectrical.com $154.73).  I appreciate all the warnings on this job.  The alternator removal and replacement was the easiest part of this 3+ hour job.  Taking off and putting back on the painted center cover and the 2 after market chrome covers (Fuel shutoff and ignition) brought back memories from when I installed those 11 years ago.   Anyways, all buttoned up and the bike started up. Battery before start 12.78, after start at idle, 13.07.   At 5,000 rpm, 14.27.   Put 120 miles on the bike on Saturday and stopped 3 times, with no hiccups.   After cooling down for an hour, I just wanted to test the amps on the battery, 12.91.   After a few beers, couple of busted knuckles and too many swear words to count, I'm glad I did and it is now completed.  Now I wash the bike.  Thanks again everyone.

[jmann]

Just a note of thanks to everyone that offered their respective device.   I put in the time and after doing the shop manuals charging system test(s) and inspections (Chapter 16), I was able to determine that the alternator was indeed the problem.  After careful removal of all necessary parts to get the alternator out, I was able to test the alternator cable and the Battery voltage input and charging lines.   I ordered the HITACHI LR140-718A (rareelectrical.com $154.73).  I appreciate all the warnings on this job.  The alternator removal and replacement was the easiest part of this 3+ hour job.  Taking off and putting back on the painted center cover and the 2 after market chrome covers (Fuel shutoff and ignition) brought back memories from when I installed those 11 years ago.   Anyways, all buttoned up and the bike started up. Battery before start 12.78, after start at idle, 13.07.   At 5,000 rpm, 14.27.   Put 120 miles on the bike on Saturday and stopped 3 times, with no hiccups.   After cooling down for an hour, I just wanted to test the amps on the battery, 12.91.   After a few beers, couple of busted knuckles and too many swear words to count, I'm glad I did and it is now completed.  Now I wash the bike.  Thanks again everyone.

Funny, I just removed and repaired my alternator last week and did not have to remove any covers at all to get mine out or back in. I did have to move the over flow tube from the coolant bottle and the negative battery cable but other than that it was easy peesy. 

[ThreeAces97]

Funny, I just removed and repaired my alternator last week and did not have to remove any covers at all to get mine out or back in. I did have to move the over flow tube from the coolant bottle and the negative battery cable but other than that it was easy peesy.  cooldude

Is there pictures/instructions/videos for repairing?  I haven't checked yet.  Thanks.  Repairing the old one is going to be my winter project.  I could not for the life of me get the alternator in a position that would allow me miss the center cover.  I also had to pull the 2 cables to the side.

[jmann]

Funny, I just removed and repaired my alternator last week and did not have to remove any covers at all to get mine out or back in. I did have to move the over flow tube from the coolant bottle and the negative battery cable but other than that it was easy peesy.  cooldude

Is there pictures/instructions/videos for repairing?  I haven't checked yet.  Thanks.  Repairing the old one is going to be my winter project.  I could not for the life of me get the alternator in a position that would allow me miss the center cover.  I also had to pull the 2 cables to the side.

Take a look in shop talk for the info on repairing the alternator. I replaced the brushes and also the rear bearing. A honda shop manual is also a wonderful tool to have on hand for repair info.