How do you test your alternator for voltage and amps?

[Steel cowboy]

Yesterday I pulled the bike out of the garage and started it to warm up. The starter cranked over like always. When I shut her down to go in the house for a few minutes I came back out and the starter barely cranked over like the battery was dead. The battery was showing 11.5 volts. The head lights were all bright. So I purchased another battery and all was good till I got about 2 miles from the house. The bike JUST SHUT DOWN when I came to a lite and like earlier in the day the starter was to slow to crank her over. Head lites were just as bright as if the battery was fully charged. I hooked some jumper cables to a car and let the battery charge up for a minute or two and she started up (the starter went off as if the battery was fully charged). What do I need to test the alternator putting out volts and amps, loose connections, fuses?
I'm stumped as to why she stalls out and starter barley cranks over and with a 2 minute charge it cranks over just fine. And the lights aren't dim when I turn the key on before the starter. Also before I forget she is running very rough at low speed now since this issue popped up.
Thank you for any input of advice guys.

[R J]

 
1st thing I'd check is all the ground cables for being clean and tight.

Then I start checking for voltage in & out of the Alternator.

Sounds like it is a ground looking for a place to land and do it's thing.

[xman]

There can be issues with the start button, starter relay, starter, connections, etc that all look like a week battery. You had a new charged battery, but without being charged while your running it will be dead in a short time. Use a digital volt meter and you will be able to find the issue.

Start with the basics. All the connections. As said a bad ground. If the problem is intermittent, you can add additional grounds from the battery to the engine. When it's running,  at the battery it should be 14.2 -14.5 VDC. That's all the time running. Much more than that and if it's  run for some time you will cook the battery. These bikes are prone to alternator issues at some typical  mileage  they need brushes or have other failures. Worse case would be an intermittent no charging problem.

[Steel cowboy]

Thank you for your replies. Anybody know how to check an alternator or were the grounds are other than the negetive side of the battery. I can take apart my Honda Sabre blind folded but the Valkyrie is too new to me .

[Steel cowboy]

Well some further testing, and I believe all alternators are alike, I have no voltage coming from it. Is there a regulator/ rectifier some were I can test too? And is there a site were I can buy the brushes or is it cheaper to buy a new one. I would like to first test the regulator/ rectifier if there is one.

[Paladin528]

The alternator is just like a car.  The regulator and rectifier are built into it.  You would need to remove it and take it to an alternator shop or get the parts and do it yourself.

[Paladin528]

 RECTIFIER, REGULATE
31105-MN5-005
$131.61  Approx.

This is for an interstate.

[Paladin528]

While you are in there
BRUSH
31101-MN5-005
$2.52 Approx.

Brushes.  you need 2 of them

[Chrisj CMA]

Two things

One...did you put a full charge on that new battery before putting it into service?

Two...check the 55A fusable link (behind the right side cover)

[Patrick]

Yep, always fully charge new batteries.
Remove and clean battery connections, including the ground at the engine block [near left ankle].
Check fuse
Place voltmeter across battery and read voltage at about 2000 rpm. Should be about 14v.

[gordonv]

Like already mentioned, new batteries need to be fully charged. Most shops put a partial/start up charge on it, relying on your vehicle to fully charge it during use. But if your alt isn't charging it, then it dies, and could also fail completely.

You've checked your alternator for charging. No charge. But where? At the battery? then check it at the alternator. If there is a charge there, then like Chrisj mentioned, check the 55A fuse. If that is gone, no charge is going to the battery.

If you have no charge at the alternator, then you need to fix it. Most swap it out with a working one. Mine was brushes. They where dirty, and only needed to be cleaned to be freed up to move again, and make contact. They where not worn to the point of needing replacement. But I bought new ones, and will most likely change them out by next year (along with a local work party and fix some others at the same time).

Now for your question. With a multi meter. It sounds like you already know, you check voltage across a + and - wire. You check amps by placing the meter in place of a wire. But I really think you are more interested in how do you figure out what is wrong with your electrical system. I'm sure the service manual will also tell you how to go about testing for it. I would need to look.

You can DL from here.
http://valkyrienorway.com/download.html

Section 16 page 3 (page 356)

[Steel cowboy]

I will remove the alternator tomorrow and check the brushes to see if they are sticking or just worn out. Just to recap using a fully charged battery I've tested for charging voltage at the fuse at the battery and at the alternator bolt. I've tested for ampere too. Next "pull the alternator"

[gordonv]

If you haven't read yet, it can take minutes or days to reinstall the alternator.

Take care on removing it, and try to remember how you got it out, so you can put it back in the same way.

One thing mentioned in the GW install, is to align the dampeners slots at 3-6-9-12 o'clock. Mine went in easily. 15 minutes to install and close the bike back up and running.

[The emperor has no clothes]

I will remove the alternator tomorrow and check the brushes to see if they are sticking or just worn out. Just to recap using a fully charged battery I've tested for charging voltage at the fuse at the battery and at the alternator bolt. I've tested for ampere too. Next "pull the alternator"

As Gordon said, pay attention how it comes out. The angle and way it comes out is the only way it will go back in. It seems like it won't go but with patience and luck it will go swift. 

[Steel cowboy]

Ok I pulled the alternator out and it's an Hitachi LR140-722. I also found out that it was installed at the 32,000 mile mark, (37,000 now) they charged the P/O $59.00 + $20.00 to install it. I don't believe it was new when it was installed !! The only measurement that was out of spec is the Ohm test between the rings that was at 1.9 ( I believe it should be higher 2.9 to 4. Ohm ). The brushes are fairly worn with the alignment holes about a 1/16 from the contact points, kind of worn out. The rings are silver at the contact points and that can't be good either. Since there is no test for the regulator/rectifier I will be replacing the entire alternator with a new one.
Now my question is, does anybody know of a good brand? I don't see myself needing a goldwing or high output. How long should an alternator last me? Funny thing is my Sabre died at 25,000 miles and I thought that was too young. Thanks guys.

[Bighead]

If it were me I would use a high output but I have extra stuff on my bike but with that being said I am still on my original with over 100 k on it. So I think it is a crap shoot as to how long any Electrical part will last.

[Robert]

Testing any electrical system is not only about volts and it does not show the whole thing. Without a load tester voltage can be deceiving. Battery voltage at 11.8 might not be there under say a 80 to 100 amp load or might not hold at that point and drop down fast and hard. The alternator may put out 13.5 volts but at how many amps. A voltage meter used while the bike cranks can give you a clearer picture of the true nature of the battery and connections. If you are cranking it over or it does not crank long and dies or does not crank at all watch the voltage gauge and see what voltage is there. You can even use the voltage gauge to tap into the wires either plus or minus while cranking or trying to and see where the voltage drop is. But without an appropriate load, your lost, and really a little better than guessing.

[gordonv]

I don't remember exactly, but someone had bought a cheap replacement off ebay. Long term results are not in to see how long it lasts.

MARS I think is the favorite for rebuilding/replacing your OEM alt. I think it's only about $50 more for a higher output alt, and is most likely worth getting if you are replacing yours already.

[Steel cowboy]

Ha.... New alternator in and I got 14 volts after start up. It took about 15 minutes to get it back in, but 45 minutes to get the front cover and key cable to go in. What a b#%*+ trying to get all that stuff back in. One funny note the radio wasn't working after all was back in, turns out I accidentally un plugged  a few connectors during the reassembly. Now I can get to adding more bling I got the front fender guard from Rivco and the rear fender extension to put on tomorrow.
I'm taking the I/S on a weekend trip to Daytona in 3 weeks.
The Webster bike swap is tomorrow but I'm taking the jeep there. There always seems to be more Honda parts there every month.

[98valk]

The brushes are fairly worn with the alignment holes about a 1/16 from the contact points, kind of worn out.

wear limit on brushes is not the hole for assembly. There is a wear limit line on the narrow side of the brush which is approx 3/8" below the assembly hole. see pg 16-11 of technical manual.
3/8" of an inch is a lot miles left of wear.