Blowing charging fuse on throttle down?


Information and questions on GL1200 Goldwings (1984-1987)
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trenaud
Posts: 10
Joined: Thu May 21, 2015 1:07 pm
Location: phoenix, az
Motorcycle: 1987 GL1200A Aspencade
previous:
1979 CB750K Ltd
1978 CB750K
1975 400F Super Sport
1976 XL100
1975 XR75

Blowing charging fuse on throttle down?

Postby trenaud » Wed Sep 23, 2015 7:20 pm



I've read just about every post on charging systems and it seems I have a real head-scratcher:
I’ve had my 'new' 87 Aspencade only for a couple of months but it's been running flawlessly (only 50K). A few weeks back I replaced the side reflectors on the fairing with LED Lights. This required quite a bit of mucking around in the fairing, and had to partly pull the CB. I wired the leds to the front markers (position). Lights looked great, but I didn't ride that week (too hot). The next weekend I also replaced the side pannier reflectors with light conversions, wiring them to the parking circuit. Cooled off inside a bit, went to check them out... not enough battery to start the bike. I figure I left it in 'park'. Okay, jump start time. I hooked up my end and my son hooked up the other end to a car battery... backwards (a mistake he'll not likely repeat).
You can guess it still didn't start. I removed battery for charging: dead cell. New battery time. My assistant, anxious to be of some help, managed to briefly get some sparks between positive and frame with a ratchet (ground is first off, last on dammit!), but no apparent harm done. It started right up.
There are 2 inline fuses running between the battery and somewhere, 1 of which was blown. Although that didn't seem to affect anything, I dutifully replaced it (I majored in EE-fuses don't blow unless they do something). Bike ran and looked great.
As it turns out this is part of an Electrical Connections wiring harness mod, properly executed, direct-wiring the stator to the R/R, with direct lines from the regulator to the battery, both terminals, and also a new fused lead from Batt+ to the coils. Makes sense.
The next day it died about 20 miles from home, dead battery, charging fuse blown. Nursed it home by repeated jump starts, (my son's getting good at it now), after each start I yanked a fuse from various circuits to use for the charging lead. Went through about 5 all-told.
With the bike running I get about 20.3 volts output at the R/R with the charging fuse out.I don’t know if this is normal for a disconnected regulator, but it shouldn't cook a 15A fuse. I checked the regulator ground to Batt-, and checked the voltage at the sensing wire connection at the regulator to Batt+, both normal. Declared the regulator dead and replaced it the next weekend.
That worked, the charging fuse was good from idle to 3K RPM, bike happy, stator happy, I'm happy. I replaced the borrowed fuses and everything worked. I went to bed happy.
Until that weekend about 80 miles from home. Dead battery, blown charging fuse.
Ran some more tests today. The sensing wire to battery+ voltage drop is less than .5V (I hooked it to Batt+ directly anyway) and the regulator output (disconnected) is a steady 20.3V from idle to 4K. Seems regulated to me since the AC out of the stator should be all over the place.
So I put a fuse (20A this time) in the charging line. Battery +/- voltage with the bike off was 11.8V (it had started the bike twice since being charged). I started the bike and let it idle. The voltage across the battery terminals went to 12.4 and slowly climbed to 12.8 before I decided that non-catastrophic charging was taking place and the voltage reading from the unhooked rectifier was probably meaningless with no current. I brought the revs up slowly to 4K. By 3K the voltage across the battery had gone to about 14.5 volts and stayed there, just as advertised! Excellent!
When I got off the throttle the voltage instantly dropped to just under 12. Fuse was blown.

This confirms what seemed to be happening the first time I broke down. A jump start got me going and a fuse kept me going until I backed OFF the throttle. I tried this twice to confirm it. Something seems to be drawing a lot of current through the main 30A fuse on throttle-down. Something under 30A but more than 20A I think. Regulator seems good, old one was probably good too. Stator output is good or I wouldn't get 14.5V at the battery. I'm going to yank all non-essential fuses and re-try tonight.

Does anybody know if I could have started the problem ham-fisting stuff in the fairing? I can read a schematic but that only goes so far, the 30 year old spaghetti in this bike is like an early 70s color TV, it takes a guru to find his way around. When I replaced the R/R and the charging fuse didn't blow, did putting back all the borrowed fuses allow the problem to return?
Did I let my son off the hook prematurely?
...and what would cause this current drain when throttling down? I'm stumped!
Maybe I sweated



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virgilmobile
Posts: 7652
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
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83 GL1100 I
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84 GL 1200 I

Re: Blowing charging fuse on throttle down?

Postby virgilmobile » Wed Sep 23, 2015 8:24 pm

Lemme ask one question about the wiring and fuse that blows...
Does that fuse connect from the battery post to the regulator red wire and have another fuse that connects to the harness red wire.
This is important info....please be precise about how it's hooked up....
The reason...The module can peak output right at 30 amp normally...If it's fused from its red wires to the battery only,it certainly can blow a fuse...
If the regulator red wires have been separated from the harness and fused feeding the battery...it needs to be a #10 wire and a BIG 40 amp fuse.
The original wiring has the bike (red wire)and the regulator red wires tied together and THEN fused to the battery...
Another point I'd like to mention...review the regulator wires...especially the ground lug connections.

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oldishwinger
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Location: New Zealand
Motorcycle: 1986 GL1200 Aspencade

Re: Blowing charging fuse on throttle down?

Postby oldishwinger » Wed Sep 23, 2015 10:44 pm

I truly dont know much about 12v systems but the position lights are only 4w aside, so those wires are only carrying a very small amount, and to wire two more lights, granted they are leds, but you could have overloaded those wires.

They may be better wired into running lights in the front turn signal group, this should have no trouble handling the extra power needed for the leds.

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trenaud
Posts: 10
Joined: Thu May 21, 2015 1:07 pm
Location: phoenix, az
Motorcycle: 1987 GL1200A Aspencade
previous:
1979 CB750K Ltd
1978 CB750K
1975 400F Super Sport
1976 XL100
1975 XR75

Re: Blowing charging fuse on throttle down?

Postby trenaud » Thu Sep 24, 2015 4:24 pm

Virgilmobile, it appears to be a typical harness modification sold by Electrical Connection. The main power still runs through the fat battery wire to the solenoid/30A dogbone fuse. What's different, and had me scratching my head, is the red wires from the regulator now have a dedicated 'charging circuit' to Batt+ via a (previously 15A) fuse. The green wires run directly to the battery. Everything is soldered and shrink-wrapped, no block connectors. The mod includes a dedicated feed to the coils as well, via relay, with it's own 10A inline fuse that's said to improve coil performance. This whole concept is supposed to eliminate all the connections of the main harness. The downside is the 15A fuse that was there is a bottleneck on a 30A system.
Actually the 2 red wires from the regulator (12ga?) go into a sleeve by the R/R (along with the yellow stator wires), what comes out the bottom is a pretty hefty single wire. It has an iffy-looking inline fuse holder that should be replaced with a heavy-duty waterproof one. Given that the circuit is robust enough to handle way more than 15A. I'd have done this modification myself.

UPDATE: Your comments got me thinking, I fired it up at lunchtime after removing the tail and parking fuses. No problems. That told me where to look. When I added the new lights (standard on the LTD, add-on with the Aspencade) I was careful to solder and shrink-wrap. I used high quality bullet connectors for the panniers. The previous owner tried to add a plug for trailer lights using mainly quick splice connectors, twisted wires and electrical / duct tape which has melted and smeared into a jumbled mess. There are 2 walmart-style orange led clearance lights on the panniers that gots to go. I know some clearance lights draw huge current, even LEDs and snipping those solved the problem. They were ugly anyway.
In short, bike is better now than it was. Looking forward to putting it back together (with a voltmeter on the dash), thanks for the help!
...now for the dogbone mod, and belts, tires, springs, seals...

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virgilmobile
Posts: 7652
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: Blowing charging fuse on throttle down?

Postby virgilmobile » Thu Sep 24, 2015 10:05 pm

Look for a dark location for the volt meter.Especially if it's a LED digital one.
I tried 3 different "dash" locations where I could see it...daytime sun mostly washed it out..I settled on a location just to the left of the front fork,on the inside lower part of the faring...It's always dark down there...easy to see even with the sun right overhead.




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