Quick fix, circuit breaker, save your brick from burning.

[rbm]

TMG, I think the idea is sound, but it's going to have to require some experimentation.

There are a number of constant voltage unfused circuits in the motorcycle:

• FI relay feed
• injectors
• temp sensor
• LSR
• Ignition sw

If ever there was a fault that caused a short circuit current draw from the battery on any part of the wiring upstream of the fuse box, then that wiring would burn up.  Daveson has chosen to install a protective device in a subset of of the above listed circuits to protect the wiring.
 He stated his objective was to add such a device because the ageing insulation in the bike could increase the risk of such a short happening.

You're right, this device needs to bear the typical current that would flow through this part of the circuit without tripping.  And it has to trip when current through it exceeds that which can be carried by the wiring before the wire heats up and burns the insulation.  The BMW engineers would have designed the system to only draw sufficient current to not exceed the safe operating envelope of the upstream wiring.  For example, once the engineers knew all the system current requirements under typical operating conditions, then they would select a wire size that could safely handle that current after being suitably derated.  Therefore selecting a protective device like a circuit breaker that is rated for the maximum current bearing capability of the diameter of wire means that it can also safely handle the typical system load under normal conditions without tripping.  It's only when a fault occurs in the wiring upstream of fuse box that causes a short circuit that the breaker trips.

[daveson]

Hi

I did some more tests and replaced the circuit breaker with one of 10 Amps.

First I repeated the short test on the first circuit breaker, but this time measured the current as well. It was about 100 Amps,  again it didn't trip,  so I think it's crap, because it was supposed to trip at about 47 Amps.

Next I tested three ETA circuit  breakers, 10 Amps,  15 Amps and 20 Amps. They all tripped with the trip test. Then I did the load test with the 10 Amp,  it didn't trip, and didn't get warm, so I assumed the others wouldn't. This time I remembered to include the horn. It's also good to think that all components will never be powered at the same time while riding anyway.

I haven't done the test ride as the weather is lousy, but I'm confident it's less than the load test.

Since it passed the load test and  short test (test ride to come) I think I can now consider this as job done.

If there are any unwanted trips, it will be replaced with a 15 Amp.

Was I right in assuming this method covers all the unprotected wires except those to the starter relay and alternator/battery?

[daveson]

Circuit breaker photo.

[daveson]

So it has passed the last test,  a couple of test rides. I don't know if this is a B curve circuit breaker, but the insulation seemed undamaged by the short test.

I spose I'll leave it at that.

Thanks everyone, not just for the steep learning curve, but I just found this one really interesting. And thanks again Rob for fixing this modification.

I'm bloody rapt.

[daveson]

Update: Removed the 10 Amp circuit breaker and replaced with the 15 Amp one, in the photo above.

After about ten rides of one hour,  and say another ten at fifteen minutes, the last two rides of fifteen minutes resulted in a total of two unwanted trips. The low beam headlight was on for all rides,  but while the indicators and brake lights were also on, the circuit breaker tripped.

So from today on I will be riding with the 15 Amp relay, and see how it goes.

[Laitch]

. . . while the indicators and brake lights were also on, the circuit breaker tripped.

During the next testing phase, also beep the horn. Just don't inadvertently launch anybody into road rage. :giggles

[daveson]

Yep, good idea, I'll try that on an empty road. I spose in an emergency you could have just about everything on at the same time.

All three passed the load test, with all lights on for one minute, but I only pressed the horn for about one second,  didn't want to draw attention. I guess it failed the test ride because the engine was at operating temperature. The first of the two trips was after three sweeping left hand turns,  so lights on longer than usual,  plus I spose 10 amps is just too low.

Hopefully the 15 Amp will last a year with no trips, if not,  I'll go 20.

[daveson]

OK so this quick fix wasn't as quick as I thought,  but I'm thinking this latest test will be the last,  since it past this combined load test and test ride.

At normal operating temperature, on a long straight empty road I had the horn and all lights on for one minute, that is hazards, brake, low beam plus horn and high beam flasher buttons pressed at the same time.  It's hard to appreciate how long one minute is until you ride with all lights and horn on for one full minute. It's a really,  really loooonng OCD amount of time.

Plus I'm going to push a proper battery isolator further up the "To Do" queue, as so many here have already done.

[Laitch]

It's hard to appreciate how long one minute is until you ride with all lights and horn on for one full minute.

It's easier to appreciate if you've stood in front of a stranger who was pointing a loaded firearm at you.

[daveson]

Wow, that minute would be  hours longer than the minute I was thinking of.

[daveson]

Update,

One year and 3,000+km later, I think I can call this job done. There have been no unwanted trips, and as originally tested with a deliberate dead short it tripped with no noticeable damage.

 It still seems odd to me that with the load test showing 25 Amps, that a 15 Amp circuit breaker doesn't trip, but I accept the reasons given and this example also shows that 15 Amps is good.

[alabrew]

Sold Out. 

Maybe put a flip switch in the line...would also work to disconnect the battery during non-riding periods...

[Arktasian]

http://products.pollakaftermarket.com/viewitems/circuit-breakers-high-amp-type-i-type-iii/e-breaker-type-iii-switchable-manual-surface-mount

Not that I recommend doing this, I can advise where/ how to source that breaker. Pollak type thermal breakers, different amp ratings and the above link for the manually resettable version

[daveson]

Yep I originally had a manual option version but it was faulty and I chose the wrong size.

I hate to admit it but a kill switch is still on my "To Do" list.  Dunno what the sold out comment refers to.

[alabrew]

Sorry, the anti-spark connector TMG linked from eBay is sold out.

Anyone seen johnny lately?

[Laitch]

Sorry, the anti-spark connector TMG linked from eBay is sold out.

Not exactly. When you copy the product title and paste it right back into the eBay search window, you get this.

[volador]

Anyone seen johnny lately?

yeah, he fell in the fecking lake while bird watching in the chee

[daveson]

Finally fitted a battery kill switch. The green circular knob at the bottom, it can be unscrewed and removed for anti theft, or just screwed out to disconnect (I moved the cigarette lighter for the photo)

The circuit breaker can be seen on top. Is this the only time you could get away with using a white cable tie, since the circuit breaker is white? I know the coil cover is black, so I'm wide open for attack on that front.

[Laitch]

I know the coil cover is black, so I'm wide open for attack on that front.

It isn't black; it's shale or maybe graphite.

[milq]

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.


Connectors.jpg (16.75 kB . 576x576 - viewed 1221 times)

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

Do those clamp down on the cable as you tighten the shroud? Or do you solder them to the cable?

[The Mighty Gryphon]

They are soldered on to the cable.  I made a new negative battery cable using very flexible, tinned marine battery cable.  Crimped ring connectors at the ends, and a little extra slack in the cable to make it easier to reach the disconnect in an emergency.  Bike runs great with the new cable.

[BrickDad]

Finally fitted a battery kill switch. The green circular knob at the bottom, it can be unscrewed and removed for anti theft, or just screwed out to disconnect (I moved the cigarette lighter for the photo)

I use these, well-made and at a very low cost:
https://www.tills.de/motorcycle-battery-disconnect-adaptor.html

[daveson]

To save my ass in a legal sence, I should add that this modification means that the headlight cuts out when the circuit breaker trips,  another way would be to tap in after the load shed relay before fuse 7, rather than before the load shed relay. I probably won't make the change on my brick though.