Topic: smoked a harness

[marc]

got a 78 k model that i had to put a wiring harness in,because the heavy main ground wire in the stock harness  was melted. used a quality harness and up graded to a reg/rec combo. ran great,charging system was putting out 15 volts! little high but i figured it was ok. using a sealed battery. new fuse box also. yesterday i noticed it kind of struggled to start,so i broke out the volt meter to check things out. the battery had 12.4 volts cold. the starter pulled the battery to 8 volts.? so i kicked started it to check the charge out put. only 13.4 at 4000, . well the bike stalled so i hit the start botton to get her going again. once, twice holy smokes!!!!  really ! it melted the main heavy green main ground wire that comes from the reg/rec. from the harness to the reg/rec plug. . looking at the wiring diagram this is the main ground for everything. i have put several hundred miles on her with no problems then this. any ideas

[Jerry Rxman Griffin aka MuthaF'er]

You sure the reg/rect is wired correctly? Many of these come with 2 unlabeled and miscolored (for our bikes) wires.

[Mr Freeze]

The biggest problem with some of the Regulator/rectifier combo units is that they often don't have a voltage adjustment for the regulator, so everything in the system sees much more voltage than it should.

[calj737]

15v to your battery is a clear indication of an incompatible reg/rec and your battery will not tolerate that, under any circumstances. Max output from a proper function ing reg/rec to battery is 14.4v. Any more than that, and you're buying batteries and other essential electrical items.

I don't know the technical background on the melted ground wire, but because the alternator is grounded to the frame and thru the reg/rec and the battery is thus grounded to frame directly, I can only imagine the heat it was seeing. Must have been pretty at night!

[scottly]

well the bike stalled so i hit the start botton to get her going again. once, twice holy smokes!!!!  really ! it melted the main heavy green main ground wire that comes from the reg/rec. from the harness to the reg/rec plug. . looking at the wiring diagram this is the main ground for everything.

The electric starter draws 10 times the current that normally flows through the green wire. There should be a VERY heavy black wire or braided strap from the battery - to the frame. If this is missing or not making a good connection, it would explain the melted green wire.

[Grinnin]

ran great,charging system was putting out 15 volts! little high but i figured it was ok. using a sealed battery.

There are different kinds of "sealed" batteries, many of which cannot tolerate higher charging voltages.

With a regular flooded battery at 15V you'll "boil" the water away pretty quickly.  Most sealed batteries are still vented a little and you can still boil away the electrolyte.  Trouble is you cannot replace it.  (It's not boiling by heat, but electrolysis that splits H2O into hydrogen at one plate and oxygen at the opposite plate.)

When I put a Deka AGM battery in my 750K5 I looked up the charging specs on their web site and then turned down the voltage on the stock regulator.

[marc]

i used a ricks motorsports reg/rec kit . i have used these before with no problem. wonder if they sent the wrong one . pn 10-100 for a field excited charging system.  the ground strap from the battery to the frame / engine mount seems fine. tight and no corrosion.  hhmm    electrical is funky.  dont understand why the system dropped  from 15v  to 13 volts output. and the starter was killing the battery. could over charging the battery couse it to lose a cell.. still shows 12.4 volts. could the stater shorting out couse this. have not checked it yet.   confusing?

[calj737]

Dropping voltage from use of the starter is normal, but a ride will/should recharge the battery pretty quickly. The function of a reg/rec is to monitor the battery's need and manage the output of the alternator. The RR should never allow 15v to a battery. If it has, then your battery is toasted.

Possible problems are in the 12v sensing wire from the Rick's RR (black wire). That should be connected to your ignition switched 12v wire. Is your RR connected directly to the battery via an inline fuse? Mine is, using a 30a.

If you read through their literature, they instruct very clearly about measuring the voltage at the battery, then disconnecting the harness and measuring the voltage sensed at the black wire. It should be between 0.2 and 0.4v difference maximum. If it's greater than 0.4v, then the RR will instruct the alternator to produce in excess of 14.8v and perhaps above 15v to the battery. This kills the battery.

Sounds like you need a new battery, and you need to do some troubleshooting on your charging system before the fire dept get a call.

[marc]

i am trying to absorb all of this, i failed electrical 101 lol. so if i have a voltage drop to  sensing wire it will kick the alt in to high gear,over charging the battery. (sensing wire is the black wire that went to the old reg)? the battery then dumps all the excess voltage to ground,but we have a flood of over charge so it fried the green ground wire and killed the battery. but the wire didnt smoke up until i hit the starter???  no poped bulbs. the wiring didnt smoke up until i hit the starter button, thats what confuses me

[calj737]

Why don't you start with documenting what you do have, and how it's wired. Draw it up or write it out. I'm sure some of the electrical mavens will be able to help pinpoint the flaw.

I used http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf to troubleshoot my way through my recent re-wire project. That, a good multimeter, and tons of help from Lloyd (TwoTired) and I think I've got it finally right.

Be prepared, if you don't make the effort to understand and perform these routines, you'll get little constructive help from those who know this like the back of their hand. They're all very willing to help those who help themselves, if you know what I mean. Me, I might be a tad more gentle on you knowing how frustrated I was just last week. And I am still not schooled in this stuff. But I do at least now understand the principles and schematic flow a lot better.

[marc]

ya know some times things just get a bit over my head, i read the manual, go on the web sites and try to learn and understand things that are pretty confusing.   ALWAYS  DO WHAT YOU ARE AFRAID TO DO. but when you screw it up go to somebody who knows. thought i was doing that when i came to this site. but i feel a little bit of snottyness in your reply,(calj737). i can get that from my local dealer thanks. think i will look some where else   

[calj737]

If you detect snottiness, then you complete misunderstood me. I am very willing to provide as much useful information as I can, based  upon my recent efforts. I was merely trying to aide you and save you the terse replies that might come your way from some other members.

So, me, they or others, will still need some documentation from you. As best you can, draw or describe what you have. Is it stock, aftermarket, has it been changed? These little factors will greatly influence the correct determination of your problem.

I provided the link I used as an aide. Like you, electrical is overwhelming to me. But with some guidance and effort, I was able to walk thru some of it and report the findings. Let's try that with your bike.

Do you have a multimeter? If so, are you familiar with using it? If not, you'll probably need one, if not now, soon. Everyone is here to help. These posts are tone-deaf so bear that in mind.

[marc]

i know it s been awhile, just got arounfd to finishing up other projects, back to the 75o charging problem. got a new stator winding,and repaired all the wiring that was damaged. topic is black sensing wire from the R.R. to the battery?  question is wire it directly to the battery with a fuse 30 amp?  making sure i understand right. the wire from the switch does show a voltage drop to 11.7 when the battery shows 12.5. installed a new switch but the voltage is the same. i am using an aftermarket wiring harness so i think that it is the problem.
 when i wire the black wire to the battery the charging voltage tops out at 13.9-14-1   when i use the wire coming from the switch the voltage goes to 15.0 14.9 15.0 14.9, so i am assuming that is the problem

[Muckinfuss]

wire and insulation melt down isn't usually a function of voltage.....it's a function of amperage.  Volts don't create heat, amperage does.  Too much current flowing for the wire size.  I think you're missing a ground somewhere or you have a current draw that could be a short, but only when the key is on.  These charging systems aren't known for their high amperage output but shorts and over limit current draw on a wire will make your life miserable. 

[calj737]

Did the '78 models really use a 30a fuse? That seems awfully high.

Yes, your black wire from the Reg/Rec needs to monitor the battery directly to help limit the alternator sending too much voltage to the battery.

[marc]

when i wire the black wire from the r.r. it sucked the battery dead?

[calj737]

That sounds unlikely. The BLACK is a monitor for the Reg/Rec. If anything it is an indication you're not putting a charge to the bike, not drawing from it.

Can you provide some info around the circumstances?