Alternator Inconsistant voltage


Information and questions on GL1500 Goldwings (1988-2000)
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NetTech94
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Alternator Inconsistant voltage

Postby NetTech94 » Sat Mar 26, 2016 2:46 pm



Last year replaced my alternator from reliable source not a EBAY special or Chinese replica. Also bought new AGM battery at same time

Had it installed by local Honda Dealer. The issue is that voltage is variable depending on what speed you are driving.
Startup- about 13.5 but slowly builds up to that as bike warms up

Digital Voltmeter on board wired to the ACC connection below seat
Stopped with no brake on just sitting.... 12.5v
45mph - 13.1 to 13.4v
55mph - 13.5 to 13.7
60-65 - 13.8 to 14.1

Rapid Acceleration: go as high as 15.4 but usually 14.8 to 15.2.

Using a Fluke voltmeter with Motorcycle turned off the battery shows 13.07 volts after 40 minute ride.

Normal or do I need to investigate further. My concern is that at low speeds my voltage will be in the mid 12's (12.4 to 12.7) when riding at or around 30 to 35mph. I'm not normally riding at these speeds but if was in traffic this could be an issue.

Thanks for reading this

Bob



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Dusty Boots
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Re: Alternator Inconsistant voltage

Postby Dusty Boots » Sat Mar 26, 2016 3:03 pm

What electrical loads are you placing on the alternator during those test (ie extra lights/radio/grip heaters etc) and what is the rated amp output of your new alternator??

NetTech94
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Re: Alternator Inconsistant voltage

Postby NetTech94 » Sat Mar 26, 2016 3:14 pm

The basics. the lights but no other accessories. The after market driving lights are not connected due to a problem of past. I wanted to get them hooked back up but for right now they have been disconnected from any electrical source. The only other thing that I have is a BACK OFF modulator for brake light.

NetTech94
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Re: Alternator Inconsistant voltage

Postby NetTech94 » Sat Mar 26, 2016 3:18 pm

I just took that fluke out and connected it and found that the onboard meter is about .5 off . So when I'm at idle it looks like I might be at 12.8 or 9. I have sent a inquiring to Motorcycle Alternator Repair Service (Ken Heming) about the alternator awaiting his response. http://myplace.frontier.com/~hemi-roid

Thanks for looking

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ct1500
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Re: Alternator Inconsistant voltage

Postby ct1500 » Sat Mar 26, 2016 5:06 pm

12.8 at idle for an OEM equipped bike is not normal. What idle RPM are you running? When doing electrical checks they must be done with a known accurate meter off the battery.
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NetTech94
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Re: Alternator Inconsistant voltage

Postby NetTech94 » Sat Mar 26, 2016 5:22 pm

That is what I thought? I believe more along 13.5 to 13.8 would be acceptable. In the past even with the original alternator I do recall when I came to a stop the bike was running in the 12.8 area. So possible that this bike has some other draw on it that I don't know. The previous owner put an auxilary fuse assemble right in front of the battery maybe pull some of these fuses out and see if I notice a increase. The trace it back to what it is connected to

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ct1500
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Re: Alternator Inconsistant voltage

Postby ct1500 » Sat Mar 26, 2016 5:41 pm

ct1500 wrote: What idle RPM are you running?


AND??
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NetTech94
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Re: Alternator Inconsistant voltage

Postby NetTech94 » Sun Mar 27, 2016 12:03 am

at idle its showing around 800rpms. Maybe a bit more. This is where its showing around 12.4 or 5 on the onboard digital guage, but on the fluke its showing around 12.8 to 13.0.

At around 2k it shows 13.5 to 13.7

I got an answer from the alternator repair person he stated that its operating as expected. I will say that at 60 to 65mph it is right round 13.8 to 14.1 consistently.

There is an add on fuse block that has wires going to the controller for heat clothing, plus one for a auxilary input. I disconnected all of these so I just had the leads coming from the alternator. Even with nothing connected but the +/- from the alternator it still only showed 12.5 on the onboard meter. I'm thinking that if I need to change out the alternator again I'll get a compu-fire one. It might be worth to take it to someone that confirm if its a alternator issue or battery or wiring somewhere. The alternator guy there is nothing wrong and since the warranty is beyond the 1 year he has nothing to gain if its not

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Big Blue UK
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Re: Alternator Inconsistant voltage

Postby Big Blue UK » Sun Mar 27, 2016 3:14 am

Try another digital voltmeter, I replaced mine during the winter.
If at first you don't succeed, hide the evidence.

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Dusty Boots
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Re: Alternator Inconsistant voltage

Postby Dusty Boots » Sun Mar 27, 2016 7:03 am

Try taping into another wire in the bike's system as there is going to be a certain amount of voltage loss, using the accessory output terminal at the fuse box. (I just use that to trip my relays for my aux wiring harness)

Your readings sound fine and Ken knows his stuff! Your alternator charging output increase with engine speed!
Compu-Fires are not all that reliable! ... but at least they can be rebuilt at any/most auto electric places DAMHIKT!!

I have 2 aux fuse panels to run all my added electrical accessories and if done right, they won't cause you any grief if your alternator is up to snuff and you don't exceed it's charging output.


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ct1500
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Re: Alternator Inconsistant voltage

Postby ct1500 » Sun Mar 27, 2016 8:03 am

No vehicle manufacturer would consider a charging voltage of less than 13.5V on a conventional regulator system as being normal or within specs and is the rock bottom low at idle or higher RPM. i.e. not one of the newer ECM controlled systems. Honda's own min spec is 13.5V. :)
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NetTech94
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Re: Alternator Inconsistant voltage

Postby NetTech94 » Sun Mar 27, 2016 2:34 pm

After reading everyone's response. It more or less confirms my suspicion. Even though the builder says its normal, I 'm not going to accept his reasoning. Think its time to find another source for a new alternator. I totally agree with everyone's assessment anything below 13.5 at idle is not normal.

Can I get some suggestions for another source for a dependable alternator. I have read some negative and positive reviews on the CompuFire.

Anyone ever use this one http://www.amazon.com/LACTRICAL-ALTERNA ... ingdocs-20

Or just stick with a OEM?

As for testing different locations, I have tried that and I am using a FLUKE digital voltmeter. I trust this one to be accurate to within .1volts

NetTech94
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Re: Alternator Inconsistant voltage

Postby NetTech94 » Sun Mar 27, 2016 4:35 pm

Disconnected lead to auxiliary fuse assemble that is mounted on battery assemble. It has 6 fuses on it one of the leads goes to rheostat that controls heat for gerbings (which I don't use). another goes to what I believe is the auxiliary power input like cigarette lighter on dash(which I don't use). So nothing loss hear

Checked to see if I had all the other primary systems ie... brake light, turn signals, horn, radio etc.. every else working

First thing I noticed is when I started it the volts where 12.5 in less than a minute, it climbed to 13.7 with choke on. So far so good. Reduced choke and it dropped to 12.8/9 area.
Off the ride, low speed now show about 13.5 to 13.8. Higher speeds 60/65 show 14.7 to 14.9

Rapid acceleration will go in the area I don't like 15.2 but it settles right down when I let off and settle in at 60mph

I think there might be ground somewhere in that auxiliary fuse box. I'm going to ride for a few days without it connected and see if it makes a factor in anything.

I guess the good news is that I don't need a alternator. Obviously its doing its job.

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Mh434
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Re: Alternator Inconsistant voltage

Postby Mh434 » Sun Mar 27, 2016 7:27 pm

I'm one of those who opted for the Amazon-sourced LActrical units (mine's the 95 amp version). It installed easily, and seems to be performing in excess of my expectations. It makes more juice at idle than the OEM unit did maxed out. With extra lights, heated accessories, etc., it's an important upgrade. While the Compu-Fire units are the "original upgrade" alternators, the price was waaay too high for me, whereas the LActrical units are very reasonable.

I get 14.1V at idle (it occasionally drops to 13.9 when I turn on all the lights, light up the brake lights, turn on heated grips etc., but only for an instant - it compensates for the load in a fraction of a second, and is back up to 14.1V again). I installed new, OEM rubbers when I installed it, and have had no issues with vibration, noise, etc. All is good.

Also - it goes without saying that an upgraded battery (AGM-type or similar) should be installed with a higher-output alternator.
Last edited by Mh434 on Sun Mar 27, 2016 7:32 pm, edited 2 times in total.

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Bluewaterhooker0
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Re: Alternator Inconsistant voltage

Postby Bluewaterhooker0 » Sun Mar 27, 2016 7:28 pm

My opinion is that your stock alternator is working about as well as any of the OEM units ever did (based on mine, and reading related posts). If yours is OEM, and original to the bike, 1994, then you probably have one of the more reliable ones made. The later units (again from reading information), were made in China from '96 on, and suffered a high rotor failure rate (as did mine - '97). I installed a Lactrical 85A unit in January of 2015 after my OEM failed due to a broken rotor winding. My recollection of the performance of the OEM was pretty close to yours.
Now, I had replaced the OEM headlights with 55W-60W bulbs, a 20W increase over the 45W/45W OEM bulbs, when on low beam, 30W increase on high beam. I also replaced the 25W OEM "cornering lights"/driving lights (mine are on all the time) with 35W bulbs, another 20W increase. I have additional LEDs in various places, but their load is negligible. I also replaced my brake lights with LEDs, reducing the load during braking.
The OEM alternator was apparently, notoriously borderline adequate (40A) for the basic loads on this bike. As such, any increased load maxed it out, and made it borderline inadequate. That was my experience. With some good high speed road time, it would keep the battery up to a functional charge. But depending on your load, symptoms such as dimming headlights on braking, or increased brightness when revving the engine, were typical from my experience.
The new 85A Lactrical cured all those issues, and seems to keep the battery in a better state of charge, based on the length of time a 'Battery Tender' takes to cycle. The time to cycle off is much quicker when a charger is attached.
Your alternator is probably about as good as the OEM units ever were. Cleaning or replacing the brushes might or might not offer some improvement. A new, higher output unit in the 80 - 90A range would most certainly be an improvement. It just depends on what symptoms you are experiencing, and your level of tolerance. If you chose to replace now, your OEM would make a good backup for that time when your primary fails.

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ct1500
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Re: Alternator Inconsistant voltage

Postby ct1500 » Mon Mar 28, 2016 7:07 pm

As the name implies a voltage regulator regulates charging voltage and keeps it within a narrow band of a few tenths.

Yours goes from 12.5 to 15.2V, something very wrong there.
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Re: Alternator Inconsistant voltage

Postby Bluewaterhooker0 » Mon Mar 28, 2016 10:13 pm

ct1500 wrote:As the name implies a voltage regulator regulates charging voltage and keeps it within a narrow band of a few tenths.

Yours goes from 12.5 to 15.2V, something very wrong there.


This is my understanding of an alternator function.

"The voltage regulator controls the field current applied to the spinning rotor inside the alternator. When there is no current applied to the field, there is no voltage produced from the alternator. When voltage drops below 13.5 volts, the regulator will apply current to the field and the alternator will start charging. When the voltage exceeds 14.5 volts, the regulator will stop supplying voltage to the field and the alternator will stop charging. This is how voltage output from the alternator is regulated. Amperage or current is regulated by the state of charge of the battery. When the battery is weak, the electromotive force (voltage) is not strong enough to hold back the current from the alternator trying to recharge the battery. As the battery reaches a state of full charge, the electromotive force becomes strong enough to oppose the current flow from the alternator, the amperage output from the alternator will drop to close to zero, while the voltage will remain at 13.5 to 14.5. When more electrical power is used, the electromotive force will reduce and alternator amperage will increase. It is extremely important that when alternator efficiency is checked, both voltage and amperage outputs are checked. Each alternator has a rated amperage output depending on the electrical requirements of the vehicle."

The voltage and amperage vary dependent on electrical load, and battery state of charge. From my experience with the OEM Goldwing alternator, as it is fairly inadequate for anything but the minimal load, it has a wider swing, mostly to the low side, because it cannot keep up with the load except under high RPMs. My new high output unit is pretty stable at 13.9, because it can match the load under virtually any RPMs.

http://www.carparts.com/classroom/charging.htm

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Re: Alternator Inconsistant voltage

Postby hugger-4641 » Thu Mar 31, 2016 5:31 am

Your understanding and explanation of alternator function is right on, except for one thing. The "rated amperage" output has little to do with how much current (amperage) is actually produced. What it really boils down to is this: the more load put on the system, I.E more amperage draw, the more heat is produced in the alternator. This is really the "rating" difference. A 40amp alternator could actually produce 300 amps or more of current if needed under the right conditions. Yes I said 300 or more, but the components, I.E. the regulator, brushes, windings, etc. can't take the heat. The biggest difference between a 90amp alternator and a 40amp alternator is the regulator and rectifying circuits are designed to handle more heat for longer periods. There may also be some physical difference in the size of the wire in the windings and/or a bigger housing, but this is still due to an effort to engineer in enough heat dissipation. With that said, you are still correct that the OEM 40amp alternator is barely capable of handling the typical duties of a GL1500.

NetTech94
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Re: Alternator Inconsistant voltage

Postby NetTech94 » Fri Apr 01, 2016 10:26 am

First off, let me thank everyone for their input.

Lets add a little information to the issue

Using a test light I have completed to the best of my ability looking for a short. A person showed me how with a test light how to identify a circuit if a short or ground was present. Though we did not believe it to be mainly because in 5 days the battery did not loose a charge.

History of the Wing and charging on this M/C. Bought in 2006 and added at digital voltmeter to the fairing left pocket with leads attached to acc connection just behind the rev lever.
This alternator served me well up until 2015 when it went out. This one too would only produce about 12.8 at idle and 13.8 at driving speeds.

The next Alternator showed the same issue but due to something in the build this alternator only lasted about 2 months. Had to get another. It too when first install showed 12.8 or so at idle and 14.2 normal driving speed

The current one shows 12.8 at idle and 14.8/9 at normal driving speeds but if you accelerate like getting on to a highway it will go as high as 15.2/3 on the digital voltmeter.

At my home with a fluke volt meter checking voltage there is about +.3v difference at idle compared to what the digital is showing. Meaning dash will show 12.8/9 the fluke shows 13.1

My concern as many have pointed out the 15v at the high end. Though its not a constant voltage its still present.

With every alternator that I have put in and all of them showing 12.8 at idle am I missing something or is there something outside of the alternator that would cause a low voltage of 12.8 at idle and the high end of 15.2. I understand that the voltage is regulated from the alternator by a regulator. But will all 3 alternators showing the same characteristics is there another component that may influence my readings. As for the battery: I have also changed out the battery with a new AGM battery (I did this 2 times thinking the first battery was flakey)

I'm at a point I wonder if I'm chasing something that can't be explained or resolved. My next step is either get another alternator hoping I don't see the 15+ on high end and accept the 12.8 on low end or keep what I have and be mindful of the 15.2 at high end. Which if the voltage stays true with the reading of my fluke at idle could mean I'm actually pushing 15.5

Again thanks to everyone for their input.

Next step is take the M/C to shop for electrical evaluation at least. Could buy a new one, but like my 1500

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Bluewaterhooker0
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Re: Alternator Inconsistant voltage

Postby Bluewaterhooker0 » Fri Apr 01, 2016 11:00 pm

The 12.8 at idle sounds pretty typical of my old OEM 40A alternator. It just doesn't do much charging at idle. I don't think I ever saw 14.8 at highway speeds, but then again, it will depend partially on how much additional load you have on the electrical system. Personally, I'm thinking you have no problem.

NetTech94
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Re: Alternator Inconsistant voltage

Postby NetTech94 » Fri Apr 01, 2016 11:48 pm

Thanks for your input... I'm just gonna have to watch those spikes above 14.9 to 15.2. I'm going to take the bike out for a few more test runs, this alternator is a 85amp unit. The original owner, told me he had changed out the OEM and replaced with a 65amp unit back before compufire was so popular.
After reading other post about alternators and GL1500 I'm under the conclusion that idle at 12.8 is not uncommon. Though many of the responses I have had on this post point out theirs is 13.5+ at idle. I looked up alternators on this site and found others with the low end range I'm experiencing at idle but then point out it increases with rpm or speed.
The one thing I might do is take the AGM battery and have it test. Even though it seems fine, because if I let it sit with NO trickle charger on it. It holds a steady 12.8X

NetTech94
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Re: Alternator Inconsistant voltage

Postby NetTech94 » Sun Apr 03, 2016 5:06 pm

Looks like I'm in for a new alternator.... today took the bike out and it was hitting 15.5 at 65mph and on hard acceleration it hit over 16v. Took back home put is on a fluke vm and it went as high as 16.8v sustained if I let it




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