Topic: Wiring harness help, part deux, two, sh'tayim, dos, etc...

[medic09]

Hooked the bike up to gas and started it to check on a question one of you all asked in my previous thread.

The question was, do the wires get hot or start smoking now that I've spliced in fresh wiring to the rectifier.

I ran the bike for 10-15 minutes.  I did not notice wiring getting hot, but the rectifier is definately hot to the touch.

Is this a problem?

 

As always,  THANKS ALL!

[750goes]

Hey Doc,

If the wires are not getting hot - then at least you are not pushing too much current through them - and your surgery has been a success.... whether the rectifier is 100% I cannot help you - leave it to the gurus to advise on that one....

My Votage regulator gets warm, so does the rectifier, I think they will get warmer depending on the amount of work they have to do - both have current passing through them all the time.. so it may be normal....good work...

[SD750F]

Medic09,

The rectifier should be warm at the most. If the device is working correctly, and has no internal damage or high resistive connections on the rectifier, it should be able to handle the maximum output of the 3 phase alternator. Also any issues with the battery such as a shorted cell would increase the load on the rectifier and it's heat product. Note that the battery is located right after the rectifier and before the main 15A fuse.

Check all the connections to see of they are clean. And if you have access to a multimeter, I could walk you through a diode check for the rectifier. This test is also noted in any of the good service manuals that are available.

Keep us informed...

Scott

[medic09]

Well, the rectifier got very warm to the touch.  Uncomfortably warm, but not so hot that I had to snatch my hand away.

Haven't got a multimeter, so I'll either buy or borrow one.

Thanks!

[SD750F]

Before you go out and buy a multimeter, check all the connections and verify that your specific gravity is good on your battery. The battery alone could really increase the load on the rectifiers. Just trying to save you some mo-la...

Scott

[medic09]

Before you go out and buy a multimeter, check all the connections and verify that your specific gravity is good on your battery. The battery alone could really increase the load on the rectifiers. Just trying to save you some mo-la...

Scott

Thanks.  Good advice.

I know connections are clean and secure, because they're all the new ones that I did and rechecked before tucking it all in.  I haven't got a hydrometer to check specific gravity (is it the same as uring?    I know those numbers... Just kidding.)  I *do* know that two battery cells were low, and even after adding distilled water the battery  takes much longer to charge than the ones on our other bikes.

As far as I know, I can get a sufficient multi-meter for about $20.  Or maybe just borrow one.

[SD750F]

Medic09,

If you can borrow a multimeter with a semiconductor diode check on it this would be great. Let me know and I will walk you through the check. We will check both the active voltage drop across each diode/rectifier as well as the basic diode junction drop when the rectifier is not in circuit...

Scott

[medic09]

Scott,

I haven't forgotten about this.  I need to come up with a meter.

Thanks!

[seaweb11]

I think you need a meter
Glad it's comming together

[medic09]

I think you need a meter
Glad it's comming together

Just wait...one day you'll look out the window, and the guy on the ratty-looking 750Four coming off the ferry will be me! 

Okay, so multimeters don't look expensive.  I'm seeing everything from just few dollars on ebay, to maybe $20 and up in local stores.  In addition to being able to do a diode check, what exactly should I look for to serve my purposes?

[seaweb11]

Ya, I have one. Now if I could just figure out how it works

Stick with my favorite, the idiot light. If it lights up, it works    If it don't try again.

[750goes]

Doc and Seaweb, crikey if I can use one you guys sure can

this great little device will measure voltage for you, will find out if your electric circuits leak voltage, will find out if they are not continuous along lengths through the untangleable harness etc...but I also like the idea of a test light for simple power finding issues of is it alive or not...

[SD750F]

I am particular with Fluke multimeters... Always well made and super tough cases for when you drop it of your bike's seat. May cost a few dollars more but a tool that will last a life time.

Scott

[medic09]

Considering how much I'll likely use it, I'll probalby go with a Home Depot special.  The extra few dollars can go to other parts and such.  After all, I've got three bikes (including the wife's) being worked on right now....

[SD750F]

Medic09,

If you are thinking about the Home Depot Gardner Bender Model GDT-190A for $19.99 I really don't think you could go wrong. Looks like a great meter for the price and will exceed your expectations. Right now I am not buying a thing from my Home Depot because I really think if they have enough money to give their last CEO $210 million for a bad job they really do no need my money... Political statement for the day.

Once you have the meter, write a quick note here and I will help you decide the integrity of your rectifier.

Scott

[medic09]

I meant "Home Depot" as sort of a generic description; that vs. more expensive Name Brand.

Actually, I bought a Greenlee DM-40 at Lowe's for 29.99.  Wife had a gift card from work, and kindly used it for the meter!  (Yeah, Wife!  ).  Has a nice outer armour for the drops off the bike seat, which are quite likely in my case.

Okay, Dr. Scott, where do we start?    Battery in, and hooked up, or not?

[SD750F]

Medic09,

Okay I will provide instructions for one method and then the other. That way you can first test the one that is currently hooked up on your bike. Then the other in no particular order.

Active Test with battery and electrical system active. With everything hooked up and your engine running test the following: Place the meter in the AC voltage range and check the AC voltage on all three wires common to ground or the Green wire. All three Yellow inputs to the rectifier should be the same. Then place the meter on the DC voltage range and check the Red/White wire leaving the rectifier and the voltage here should be between 12V and 14.5V. (12V near idle and 14.5V at 4000 RPM). If this or the prior test is not correct, then you have to check the individual voltage drop on each of the 6 diodes in the rectifier. Here is the simple way to check. With the meter still on the DC range. place the black reference of ground test lead on the meter on the Green rectifier lead. Then take the red test lead and note the voltage on all three wires. Again all should be close to each other (do this test at idle). Remove the test leads and placed the red test lead on the Red/White rectifier wire and with the black test lead check the voltages on all three yellow rectifier input wires. Again the voltages should all be the same with each other as well as the previous diode drop test just preformed...

Static Test with the rectifier removed from the circuit and power no applied. With all wires removed from the rectifier place the meter's function to the diode test. This will drive a controlled voltage across the test leads and read a voltage drop across the diodes junction. A typical silicon rectifier will have a voltage drop between 0.6 to 0.8 volts. So check each individual diode using the same method above and all diodes should have NO reading. That is because if the test leads where in the same location as the active individual voltage test the test leads are in reverse polarity and there should be no voltage drop and current flow in the diodes. A diode prevents a current flow in one direction and when biased properly will provide current flow in the other direction with a small voltage drop across the diode junction. Reverse the test leads and you should see this voltage drop across each diode (6 in all) all about the same reading.

Let me know your results and I can direct you in the right direction from here...

Scott

[medic09]

Scott,

Thanks for the instructions.  First snag:  I have 5 wires total.  Three Yellow, one Red, one Green.  Uppermost is Red.  Bottommost is Green.  The three middle wires are Yellow.

[750goes]

Doc,

heres a good test bed for you....it's pretty easy to work out..

[SD750F]

Medic09,

Yes you are correct. The red wire on some bikes/harnesses is a red/white wire. This is the rectified DC output. The green wire is the common ground. And the three yellow wires comes from the alternator output coils. The rest is as I indicated on my review and test instructions...

Scott

[medic09]

Okay Scott, I think I've got it now.  Still, revving the engine is going to get frowns from the wife who just headed for bed early.  I'll tackle this in the morning.

750goes, that's a great protocol.  Thanks!

So far, I know that the charged battery is showing 12v across the posts.  At about 4k rpm, it's showing only 13v across the posts.

I'll let you all know what I find out in the morning, when I can do this more systematically.

[medic09]

Medic09,

Okay I will provide instructions for one method and then the other. That way you can first test the one that is currently hooked up on your bike. Then the other in no particular order.

Thought you all were rid of this thread, eh? 

Active Test with battery and electrical system active. With everything hooked up and your engine running test the following: Place the meter in the AC voltage range and check the AC voltage on all three wires common to ground or the Green wire. All three Yellow inputs to the rectifier should be the same. All three read 13

Then place the meter on the DC voltage range and check the Red/White wire leaving the rectifier and the voltage here should be between 12V and 14.5V. (12V near idle and 14.5V at 4000 RPM). 12 @ idle; 14 @ ~ 4200

If this or the prior test is not correct, then you have to check the individual voltage drop on each of the 6 diodes in the rectifier. Here is the simple way to check. With the meter still on the DC range. place the black reference of ground test lead on the meter on the Green rectifier lead. Then take the red test lead and note the voltage on all three wires. Again all should be close to each other (do this test at idle). They all read 6

Remove the test leads and placed the red test lead on the Red/White rectifier wire and with the black test lead check the voltages on all three yellow rectifier input wires. Again the voltages should all be the same with each other as well as the previous diode drop test just preformed...All 6, again...

Static Test with the rectifier removed from the circuit and power no applied. With all wires removed from the rectifier place the meter's function to the diode test. This will drive a controlled voltage across the test leads and read a voltage drop across the diodes junction. A typical silicon rectifier will have a voltage drop between 0.6 to 0.8 volts. So check each individual diode using the same method above and all diodes should have NO reading. The meter starts at 1, and all the wires remain at 1.That is because if the test leads where in the same location as the active individual voltage test the test leads are in reverse polarity and there should be no voltage drop and current flow in the diodes. A diode prevents a current flow in one direction and when biased properly will provide current flow in the other direction with a small voltage drop across the diode junction.

Reverse the test leads and you should see this voltage drop across each diode (6 in all) all about the same reading.  I think the meter leaves the decimal to the imagination.  Top wire: 558  Middle:  553  Bottom:  555.

Let me know your results and I can direct you in the right direction from here...

Scott

Now what, mi maestro?  For whatever it's worth, when I first ran the bike today, the rectifier again felt kinda hot.  When I ran it later for these tests, it barely warmed up at all.  Also, upon closer inspection while doing this, I found that two wires (remember they were all fried somehow) had breaks in their insulation.  I covered that with electrical tape for now.  I wonder if I need to break down and spend the $45 on one of Oregon's newfangled rectifiers?

As always, MANY THANKS!

[seaweb11]

On your 1st test,did you have the key in the on possition for a few mins. before starting it? That will warm it up quite a bit.

[medic09]

On your 1st test,did you have the key in the on possition for a few mins. before starting it? That will warm it up quite a bit.

No, I didn't.

[TwoTired]

Bear in mind that juice from the battery powers all the electrical loads on the bike and the elect starter is a big one.  That big draw has to be replenished by the alternator (though the diodes) after the engine is running.

You haven't mentioned what state your battery is in: charged or depleted.  A depleted battery will place additional loads on the rectifier and make it hotter.

A fully charged, unconnected battery with no load will be about 12.6 volts.  The charging system will try to bring the battery voltage up to about 14.5V, which it can take without damage.  However, it takes time for a depleted battery to actually attain 14.5V and may do so quite slowly.  This is why charging systems are checked with a known fully charged battery.

Once 14.5 V is attained, the VREG tells the alternator to back off.  The cruise down the road Voltage will likely wander around 13.8V.

You are aware that your alternator won't make enough power to run your bike electricals at idle RPMs.  The battery depletes at that time.  And, the voltage will certainly fall with time in that state.

Any any rate, the rectifier will heat relative to how hard the charging system is trying to keep the battery voltage up.  It can get quite hot if you have higher than stock electrical loads AND a depleted battery.  When it is working hard, you probably won't be able to hold your hand on it.  That's why it has all those fins on it, to make as much contact with the surounding air as is need to keep the internal temps down to survivable levels.  Something around 70 degrees C I'd guesstimate.

Cheers,