Alternator

[Conrad]

So 50 miles into my first "real" ride of the season after going through the cooling system, my alternator crapped out. Power to the field coil, only 11.8 volts out :(
This alternator only has about 6100 miles on it, as i replaced it shortly after i bought the bike to years ago.
Puchased from db electral ( who I've had good luck with before) for about $160.
My gut tells me i just got a dud alternator, these things happen sometimes. But I'm concerned there may be an underlying issue causing this. The only added electrics i have are some l.e.d. foglights and an airhorn. I don't see these killing an alternator.

Just seeing if anyone has any insights or thoughts, thanks!

[triton28]

I'm sure you have already checked this but the Brown wire, which becomes a Black wire to the alternator from the last white plastic connector before the alternator, is the exciter voltage for the alternator output and as such it should be battery voltage when the ignition switch is ON and the engine stop switch is set to Run.
If battery voltage is present and then after re connection of the Black exciter wire if previously disconnected for voltage reading, the alternator is being driven at engine speed above 1100 RPMs and there is NOT 13-14 Volts output as measured across the battery terminals, then either there is possibly a break in the continuity of the White wire to the main 30 Amp fuse OR the alternator is fritzed.
It is a real simple charging schematic/system so there is really very little to go wrong other than the component parts/wiring.
Check those plastic terminal couplers for corrosion etc as these bikes are 21 years old at the youngest and things corrode.
Also, which may or may not be the case for your alternator, there are a lot of NON Mitsubishi/OEM alternators being sold which DO NOT utilize roller ball bearings on the opposite ends of the armature. Rather they utilize some alloy of bronze/brass bushings which will not last as long as the OEM bearing design. Unfortunate but real.
Hopefully you will find a dirty connection somewhere in the circuitry.
Let us know how you make out.
Dave

[Conrad]

Yeah, i tested it per the manual, alternator is dead. I'm sure the replacement i put in 2 yrs ago is chinese, but i don't see it being a bearing issue, it spins fine. My guess is regulator/rectifier. I still have the one i took out (mitsubishi) I'll be stopping today at a local shop to see if i can get it rebuilt.

[Conrad]

Well, shop cannot (completely) rebuild my alternator. The winding is broken in the rotor, and unfortunately they cannot get a rotor, nor can they get it rewound. Other parts they could get. However they can order a complete alternator for about $210, with a 1 year warranty. Whether it will be of any higher quality than the one i bought 2 years ago, who knows. However at least I'll have a place to return it if it fails under warranty, so I'm leaning towards that option. I took the replacement alternator apart hoping to find a good rotor, to make one out of the two, but that rotor tests bad also.
On a side note, the aftermarket alternator DID have sealed roller bearings.

[Conrad]

New alternator in, 14.5 volts at idle hope this one lasts longer!

[Bonnie and Clyde]

New alternator in, 14.5 volts at idle hope this one lasts longer!

Got any link or info on what unit you bought?

[Conrad]

The first replacement i bought 2 yrs ago was from online seller dbelectrical, a company I've had good luck with in the past. The rotor coil went bad in that one, I'm guessing i just got a dud, it happens sometimes .
This new one i ordered through a local rebuilding shop. It doesn't look any different than the one from dbelectrical.
When i get out to garage later today I'll post a pic of the box it came in.

[Conrad]

Here's the box from the new one:

[Conrad]

Plus i added one of these doodads so I'll have some warning next time

[SgtSlag]

A Voltmeter is a standard upgrade for me. Been left sitting before, due to a dead battery/charging system...

I replaced nearly all of my incandescent bulbs with equivalent LED's, several years ago. It freed up Amperes for charging my Battery. I highly recommend that to you. The OEM Alternator does not have a lot of spare Amperes for running accessories.

LED bulb replacements change monthly, as to what is available, and what their stat's are. You will need to research replacements yourself: make certain they are proper replacements, based on bulb type numbers. Also, make certain they put out higher Lumens than the incandescent versions! Make certain to use the proper color LED: yellow LED's behind yellow lenses, red LED's behind red lenses; if you use a white LED behind a colored lens, the lens will absorb all of the light/Lumens that are a different color from the lens, only passing those colors -- most of the Lumens will be lost...

The LED bulb replacements will last 20,000-50,000 hours, while the incandescent bulbs will last around 5,000-7,000 hours only. Installing an LED Headlight can save you 20-30 Watts of power, alone, that can be re-directed to your Battery, or to run other accessories. To be honest, I love the relief of knowing that the LED lights will likely outlive me! Cheers!

[Nails]

I have a voltmeter that has a color code rather than a number. Normally, I like more detail; but not in this case. All I know is that if it turns into a warm color (yellow or red), and especially if it flashes, it might be something I should pay attention to. But if it's green, I don't need it in my life. This little light is mounted behind the old Check Battery pup on the dash, which is red -- that is, I put this monitor where that white bulb used to be. The upshot is that it's hard to see when everything is fine (I drilled little holes in the red lens if I really want to check it), but raises it's ugly head only when I really want to know -- I totally forget about it most of the time. Besides not adding crap to my already silly-complicated cockpit, it also reuses that check-battery idiot light so I don't have to feel that I'm toting unnecessary weight. A win all the way around.

Warning: a total on-sequitur about weight follows.
I've been thinking of lithium batteries, primarily for dirt touring (BDR &etc) on light-weight bikes where the weight savings is more relevant than it would be with our piggly Voyagers. For those applications, I'm planning to go back to ammeters because lithium batteries maintain voltage until just before they die altogether. Probably better to monitor when, how long, and how much they're discharging.
Now, back to your regularly-scheduled program.