Author Topic: Quick fix, circuit breaker, save your bike from burning.  (Read 456 times)

Offline daveson

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Quick fix, circuit breaker, save your bike from burning.
« on: May 12, 2019, 07:10:36 AM »
Today I installed a circuit breaker.

Because these bricks will be pushing forty years old before we know it, and these wiring looms aren't as pliable as when new, its worth considering the protection of a circuit breaker. I chose the manual disconnect type, so it doubles as an immobilizer, but I will state straight up that the market for stolen bricks wouldn't be much greater than the market for stolen mortar. It could also be used like a battery isolator, in a limited sense.

Step 1. I bolted the circuit breaker to the top of the coil cover.

Step 2. Removed the fuel injection relay positive from the positive of the battery (the thinnest of the three red wires to the battery positive)  and connected it to the breaker aux. terminal. I cheated by cutting one inch of the loom sheath from the end opposite the battery, to free it from the alternator loom sheath. A bit of WD40 also helped in sliding it out.

Step 3. Snipped the red ignition switch (combined) wire to the starter relay at the relay positive terminal (the thinner of the two) and crimped a connector on to connect it to the breaker aux. terminal.

Step 4. Ran a new wire from the battery positive to the breaker battery terminal.

If I did it again, I would reinstall the accessory socket a little further back, making it easier to press the switch.

Hopefully some improvements may be suggested.
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline daveson

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #1 on: May 12, 2019, 07:18:35 AM »
Attempt 2 at adding a photo
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline natalena

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #2 on: May 12, 2019, 08:03:27 AM »
Thanks for the How-To. Do you suggest a particular type and amperage rating for the breaker? Beats the heck out of having the brick burn down the garage.
  • East of Joshua Tree
  • 1987 K75s #0919
On Holy Quest seeking Techron equivalent for splines.

Offline daveson

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #3 on: May 12, 2019, 08:16:25 AM »
Hi

I used a 40 Amp, it was cheap and close by. I thought it would show in the photo, unfortunately the focus is bad, but it was the best of about ten photos I took.
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline Chaos

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #4 on: May 12, 2019, 09:08:48 AM »
I put a battery disconnect on mine, mainly in case the starter relay ever fused shut
  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
2012 Ural 2WD sidecar (BMW's bastard step child)

Offline daveson

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #5 on: May 12, 2019, 09:21:33 AM »
Good idea,  I should probably do that too one day,  but since the circuit breaker was my main goal,  I left the battery to starter relay wire untouched since the circuit breaker wants to be about 40 Amps.

I was never worried about the starter relay problem until I got my K75 which suffered from it. From then on I kept my steel fixers insulated snips in the glove box, which makes me even more worried.
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline trek97

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  • The Anti-Cafe racer
Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #6 on: May 12, 2019, 02:15:52 PM »
Thanks this is cool.

Would you please post a link to the breaker you bought?

Mine did this twice. 

I disassembled and cleaned the start button and hasn't happened since.  But, I still think about it EVERY time.

  • Illinois
  • 87 K75C

Offline daveson

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #7 on: May 12, 2019, 04:37:01 PM »
Peace of mind is a good thing.

I don't even remember which supplier I clicked on,  there were so many options. Try eBay, type in 40 Amp  circuit breaker, choose the automotive option, and you should get many options nearby.

I usually prefer a shop. Although I'm happy with this circuit breaker, it doesn't even have a brand name. I would happily pay a bit extra for at least a name,  this one was $23. I'm not much worried though, if it fails I'll simply bolt the wires together. On the top is written waterproof, on the bottom is 40 Amps,  and ignition protected.
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline rbm

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #8 on: May 12, 2019, 05:08:42 PM »
Have you tested it?  The current rating of the breaker is not necessarily the value at which it trips due to fault current.  There are difference trip characteristics for circuit breakers and you'd have to be certain that the characteristic you chose will trip at the right current and in sufficient time to protect what it is you are trying to protect.  Which brings me to the question - what exactly are you trying to protect -  the wiring or the componentry?  Did you consider using a polyfuse (aka. battery strap) instead of a breaker?
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Online Martin

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #9 on: May 12, 2019, 05:29:38 PM »
I fitted a battery isolator switch after having the relay jam three times. The first time it happened the side of the battery blew out. See http://www.motobrick.com/index.php/topic,8995.msg70926.html#msg70926
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline The Mighty Gryphon

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #10 on: May 12, 2019, 07:15:47 PM »
I'm using one of these connectors in the negative battery cable.  Makes it possible to break the line quickly, disconnecting the battery from the electrical system.  For #8 AWG wire, gold plated, rated for 90 Amps surge /60 Amps continuous.

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https://www.ebay.com/itm/1-Pair-Amass-AS150-7MM-150-AMPS-Anti-Spark-Connector-Plug-For-HV-Bettery-ESC/302268569659?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D20131003132420%26meid%3D378bc444206641b18e1b6c828bcaf9b8%26pid%3D100005%26rk%3D4%26rkt%3D24%26sd%3D222090307045%26itm%3D302268569659&_trksid=p2047675.c100005.m1851
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too

Offline daveson

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #11 on: May 13, 2019, 01:32:28 AM »
I'm hoping to protect the wiring and components from a short, for example a short from the ignition switch wiring. A few of my bricks are showing their age where the loom rubs against the frame when turning the handlbar. When turned to the left it stretches the wiring on the right like the starter switch wiring,  more common because of the side stand and mounting side.

I considered other types, but I like the idea of a circuit breaking when overloaded (as opposed to auto resetting or adapting) as it warns me of a fault and to look for its cause.

From memory the add says trips at 47 Amps,  hopefully not too high.

The only test was to start it without it tripping out, before I called it a day.

Hopefully on the weekend I will take it for a longer ride, and to short a 0.5 and 0.75 wire in the hope that the circuit breaks within one second. On second thoughts, I should have done these four tests before I posted this thread, and included the results.
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline natalena

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #12 on: May 14, 2019, 11:20:47 AM »
Advanced apologies if this question is too rudimentary, and I should stay with turning wrenches and not fiddling with wires.

Is there a reason not to have a more direct pathway for the breaker set-up?
Battery positive terminal   to  40A breaker  to  3 Red wires that are usually attached to the battery positive terminal?
  • East of Joshua Tree
  • 1987 K75s #0919
On Holy Quest seeking Techron equivalent for splines.

Offline daveson

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #13 on: May 14, 2019, 05:12:39 PM »
Hi Natalina,

All questions welcome,  l love talking about bikes, it's a new, reborn passion of mine.

It's a big job to crank the engine, I guess it would break 40 Amps in a flash. If you go really high Amps to cope with the starter, it probably wouldn't trip if a small wire shorted. It would be nice though, if you could have it both ways.

I can't find the add where I got it from,  from memory it said trips in a few milliseconds from a short. I'm going to do some tests and make a post,  but so far I'm happy with it. But I can already say now I wouldn't recommend this brand as it hasn't even got a brand name. I went into a Jaycar shop before I ordered this one,  but the smallest one they had was 70 Amps.
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline natalena

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #14 on: May 14, 2019, 06:30:42 PM »
Thanks Daveson, much appreciated explaining the separate max load on a separate wire, even though they all congregate to one point at the battery. The schematic now makes sense to me ;)
  • East of Joshua Tree
  • 1987 K75s #0919
On Holy Quest seeking Techron equivalent for splines.

Offline daveson

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #15 on: May 14, 2019, 07:52:50 PM »
No worries, so the positive to the starter relay and alternator remain unchanged and unprotected. That doesn't worry me too much as there is basically no movement there to cause wear,  and can be easily inspected.

Another thing I would do differently, as well as in post one, I would cut the starter switch positive to the starter relay an inch or two from the relay, instead of up against it, since the wire was till too short anyway to reach the circuit breaker. I had to add a piece.
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline daveson

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #16 on: May 18, 2019, 07:15:01 AM »
Another beautiful day,  another beautiful ride and did a few tests on the bike.

Tried to trip the circuit breaker with a 0.75mm wire,  it didn't trip.  Held for at least one second, possibly three,  wire was sizzling and melting, chickened out and let go. Tried a 3.5mm wire,  tripped seemingly instantly. Surprised me first but spose it makes sense now.

Load test: high beam on, hazard on, brake on,  fan off,  horn off (forgot it); 25 Amps.

Stall test: clutch switch disabled, 5th gear,  rear brake on, start button pressed;  100 Amps.

I'm scratching my head with this a bit. Maybe 35 Amps would be better. 

Thoughts anyone?
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline daveson

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #17 on: May 18, 2019, 07:33:53 AM »
...There are difference trip characteristics for circuit breakers and you'd have to be certain that the characteristic you chose will trip at the right current and in sufficient time to protect what it is you are trying to protect. ...

Hi Robert, in the hope you revisit this thread,  I'm not certain, 40 Amps was a guess.  What do you make of all this?  I would be grateful for your opinion whichever way it falls.

I spose I should focus on a circuit breaker suitable for protecting the unprotected wires from 1.0mm to 2.5mm,  which I think are most of the red wires in the Haynes manual.

My aim is to prevent damage caused by a short in an unprotected wire.

 Maybe Natalina's idea,  with more Amps Has more merit than I first thought. What would you recommend to anyone else considering this?

Regards,  David.
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline rbm

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #18 on: May 19, 2019, 08:00:46 AM »
Any protection device added to the motorcycle is normally sized to protect the downstream wire, not the downstream load.  There are tables available that help to determine the maximum current a given wire size can tolerate.  You selected a breaker that you felt would cover the highest possible drain a short circuit would draw from the battery, however you should have selected a breaker that would cover the largest current draw the wiring can tolerate.  I'm assuming the wire is encased in a muti-conductor cable and sits adjacent to other wires and is 0.75mm diameter. From the table I linked, that value is 12 amperes.

The other aspect to consider is the trip curve characteristics of the breaker.  A magnetic circuit breaker will trip differently than an AGM automotive fuse.
 All breakers are designed to accommodate short periods of overload so they won't trip immediately.  You don't want too large a breaker so that it doesn't trip at all but you don't want it too small so that you get nuisance trips.  And you don't want to select a breaker with the wrong trip curve so that the wire insulation starts to melt before the breaker trips.

I would be guessing but maybe chose a B-curve DC breaker of 12A - 15A.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline daveson

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #19 on: May 19, 2019, 08:22:14 AM »
Bonus,  thanks heaps,  I'll try again and report back.
  • Victoria, Australia
  • Current; 1985 bmw k100rt VIN 0090567 ('84 k100RT, 87 k100RT, '89 k100rt, '91k75s, '96 Kawasaki Vulcan 1500) Past; V Star 650, Kawasaki klx250, Yamaha tt250

Offline natalena

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #20 on: May 19, 2019, 09:04:20 AM »
Thanks RBM, your information is truly appreciated.
  • East of Joshua Tree
  • 1987 K75s #0919
On Holy Quest seeking Techron equivalent for splines.

Offline The Mighty Gryphon

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #21 on: May 19, 2019, 12:40:46 PM »
From reading about the experiences of others, the main reason for a disconnect is to stop the starter in the event the start relay welds it's contacts.  Since that normally occurs when trying to start with a nearly dead battery, the current to the starter will probably be less than normal.  If you put in a breaker that won't trip when the engine is being started normally, then it stands to reason it won't protect the battery when the start relay is welded.

That is the reason why the best protection is a mechanical disconnect that the operator can easily reach.  A high current connector in the ground wire is, in my thinking, the most reliable and cheap solution for the problem.  No matter what the situation, if I need to Kill the electrical system I can do it in just a couple of seconds.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too

Offline rbm

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #22 on: May 19, 2019, 01:01:28 PM »
... No matter what the situation, if I need to Kill the electrical system I can do it in just a couple of seconds.
There are situations where you only become aware of an electrical problem when you see smoke and smell burning.  By then, damage is done.  This suggested modification is to try and trip the breaker before that damage is done.

In the case of the stuck starter relay contacts, the components that could be damaged are the battery, the thick cable between the battery and starter motor, the ground cable or the starter itself.  This suggested modification is not trying to address that failure; your idea of a master disconnect on the ground return is highly recommended.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline The Mighty Gryphon

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #23 on: May 19, 2019, 01:48:35 PM »
There are situations where you only become aware of an electrical problem when you see smoke and smell burning.  By then, damage is done.  This suggested modification is to try and trip the breaker before that damage is done.

I doubt you can accomplish that.  If you are trying to protect the primary power wiring, you need to accommodate the full simultaneous current draw of the entire electrical system.  Unfortunately, the current necessary to burn up one of the wires in that primary circuit(the fuses protect everything but the headlight) is much lower than what you will have to have as the trip point for a main disconnect, otherwise you will have the disconnect shutting down the power at very inopportune moments.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too

Offline beemuker

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Re: Quick fix, circuit breaker, save your bike from burning.
« Reply #24 on: May 19, 2019, 03:39:55 PM »
I'm using one of these connectors in the negative battery cable.  Makes it possible to break the line quickly, disconnecting the battery from the electrical system.  For #8 AWG wire, gold plated, rated for 90 Amps surge /60 Amps continuous.

thanks,I just ordered one, seems like a simple emergency disconnect
  • Panama City, FL
  • 94 K75s , Dakar yellow ABS

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