Replace Circuit Breaker with 40 amp Fuse

[smoserx1]

What was the purpose in the earlier pictures and diagrams where two fuses were installed?  It looks like this essentially places a fuse in line with the voltage regulator + output, then relocates the regulator + output to the inlet side of the battery fuse, as opposed to the exit side.  Why not simply move the regulator output to the inlet side of whatever device the bike already uses (fuse or breaker)?  That way, if the fuse blows or the breaker trips, you certainly won't get a spike, because both the battery and regulator output would be be instantly disconnected.  Of course, with things wired like this, if the fuse or breaker failed, the motorcycle would also immediately quit running because there would be no electricity whatsoever.

Like Glen said earlier, with a permanent magnet alternator (which requires no excitation) being connected to the exit side of the breaker or fuse (like the current factory setup), it looks to me like the motorcycle should theoretically remain running if the fuse/breaker blows (assuming the resulting spike or ripple does not take out the ECM, and there is not a complete short to ground in the ignition switch feed).  Maybe this way it would keep you from loosing all engine power instantaneously, which is very dangerous.  I wonder if that is why Harley does it this way?

Any other thoughts on this?

[Ed Y]

Steve,

If you'll recall, back in 2004 when HD issued service bulletin M1151 and 1151A with instructions to replace the 40A breaker with a 50A breaker because the 40A breaker failure was causing, QUOTE "These motorcycles have a condition whereby the 40 amp main circuit breaker could open due to reasons other than for which it was designed, causing an unexpected interruption of all electrical power. This condition could cause a "quit while riding" situation, which could occur without warning and lead to a crash, thereby presenting a risk of death or injury to the rider."

This would lead me to believe that a failed breaker shuts down the whole bike regardless of the supplied current from the regulator. I sure am not any kind of electrical expert but that's my understanding of what was happening.

AS to your question about why 2 fuses vice 1, I can only assume it was to provide some leeway in case the regulator went overboard and blew the 1st fuse which would still allow the bike to keep running under battery only power (for a short time only). In a 1 fuse setup, you couldn't do this. 

[glens]

Seems to me the primary reason for the Maxifuse is to protect the charging system from a failed battery or maybe somehow the starter motor should it get engaged in a hard way while the system's charging, or an eventful mis-attempt at attaching jumper cables to a running bike.  Something like that.

Not saying the voltage couldn't ever spike for some reason, but I don't reckon a 40A fuse is gonna protect electronics from one.  The fuse is a current-limiting device, not a voltage clamp.

[DavePard]

way back...seem to be that my old Nortons and Triumphs had a capacitor approx size of a D-cell for running w/out batt. kick-start

[Tsani]

The fuse is a current-limiting device, not a voltage clamp.

You can say the same for the automotve type of breaker as well. But, in my trade, we generally feel and have observed that a fuse is voltage sensitive, more so than a breaker and in many cases blows quicker than the breaker trips. A fuse will blow every single time. I have seen cases where a breaker does not trip out.

[Ed Y]

Considering all the burnt wiring that I've seen over the years on knucks, pans and shovels cause they didn't have circuit breakers or fuses to protect against shorts or overloads, I'd suggest that maybe that's the major purpose of the breakers or fuses. Granted that nowadays there are numerous fuses to protect individual circuits so the main breaker or maxi-fuse it there as the final level of protection and also to protect the charging system and/or starter/solenoid. JMHO

[Tsani]

Well Ed, a lot of guys didn't bother with a fuse on their older bikes. I know I always ran several and never had an ssue with the wiring burning up where as I had to help a buddy re-wire his on the side of the road. He ran a fuse after that.

[Ed Y]

Well Ed, a lot of guys didn't bother with a fuse on their older bikes. I know I always ran several and never had an ssue with the wiring burning up where as I had to help a buddy re-wire his on the side of the road. He ran a fuse after that.

Agreed. I can remember adding a 30A breaker with bar to the battery on many, many older bikes that had nothing.

[Admiral Akbar]

In July 2009, while my bike was being dyno tuned, my bike experienced a voltage spike that took out the ECM, TSSM, speedometer, passing lamp switch, all the bulbs, Badland Run, Brake and Turn Module, Kuryakyn LED tail lights.  The only plausible explanation is that the circuit breaker overheated and disconnected the circuit from the battery, but not from the alternator, which sent a voltage spike the fried all my electronics.

Did the head light blow??

My bet is that the bike lost the breaker and same time as the head light might have lost connection and the POS badlands brake slight thingy, fed the spike from the running light wiring back into the TSSM, killing the TSSM, ecm and speedo..  after market light thingy.. Leds.. etc...

Mayor You need to read this.. The after market break light / load / turn signal module must have been designed buy a EE that knows reliability...   (or a tech that had engineer's disease)

Max

[Admiral Akbar]

That way, if the fuse blows or the breaker trips, you certainly won't get a spike, because both the battery and regulator output would be be instantly disconnected.

You don't understand what fused are designed for.. They are to protect wiring and nothing more.. In your case, if you get a short in the wire from the battery to regulator, you'll burn that wire and possibly cause a fire.. Max

[glens]

Not so.  If the circuit actually worked (see below) the fuse between the charging system and battery would've already opened.

I understand what fuses are for, trust me.  That's pretty much why I'm questioning the double-maxi arrangement (and the relay bit was pretty much tongue-in-cheek).  I feel the way the factory put mine together is just fine.  I like it.

I couldn't remember what you were referring to so scrolled back some.  I see where I'd not made proper provision for the relay power to be interrupted by the maxi opening.  Maybe it'd be better to use the normally-closed contacts for the feed from the alternator, with the energizing coil wired in parallel to the maxi.  That way if it opens, the relay coil will be energized, opening up the alternator feed contacts.  It would make a neat little oscillator as the bike decelerates intermittently, unless/until the relay coil smokes.

The way I'd described it (at least the way I'm reading that now) the relay would remain energized by the very circuit it would interrupt if it opened, providing no real function whatsoever; just as well not even be present in the circuit.  By the same token, the potential for damage would be exactly the same as with the way the factory ships it.

... in my trade, we generally feel and have observed that a fuse is voltage sensitive, more so than a breaker and in many cases blows quicker than the breaker trips. A fuse will blow every single time. I have seen cases where a breaker does not trip out.

Well, yeah.  At twice the voltage they have half the rating, nominally.  What you're saying is not so easy a statement to make so simply.  Various types of fuses and breakers have various response characteristics.

[Tsani]

That way, if the fuse blows or the breaker trips, you certainly won't get a spike, because both the battery and regulator output would be be instantly disconnected.

You don't understand what fused are designed for.. They are to protect wiring and nothing more.. In your case, if you get a short in the wire from the battery to regulator, you'll burn that wire and possibly cause a fire.. Max

That is exactly correct Max. If one wants to clamp the voltage or stop a surge, there are other devices made for that.

[Tsani]

... in my trade, we generally feel and have observed that a fuse is voltage sensitive, more so than a breaker and in many cases blows quicker than the breaker trips. A fuse will blow every single time. I have seen cases where a breaker does not trip out.

Well, yeah.  At twice the voltage they have half the rating, nominally.  What you're saying is not so easy a statement to make so simply.  Various types of fuses and breakers have various response characteristics.
[/quote]

Actually it is pretty simple to make.  That breaker you use on your bike or in your car is not a very terribly sophisticated device. It will not "clamp" voltage and is not guaranteed to stop a spike, neither is a fuse for that matter. Fuses react to current flow, 20 amps is twenty amps be it 6, 12, 14 or 20 volts and fact is on average fuses can be 5 times faster blowing on a short than that breaker in your bike. Now if you want to retro fit one of the newer technology breakers in....whole different ball game. But have fun doing that. As Max stated, all the fuse or circuit braker does in this case is protect your wiring. And tho they stand a better chance with a fuse or breaker, damage can still occur to the electronics.

[Bagger]

Actually it is pretty simple to make.  That breaker you use on your bike or in your car is not a very terribly sophisticated device. It will not "clamp" voltage and is not guaranteed to stop a spike, neither is a fuse for that matter. Fuses react to current flow, 20 amps is twenty amps be it 6, 12, 14 or 20 volts and fact is on average fuses can be 5 times faster blowing on a short than that breaker in your bike. Now if you want to retro fit one of the newer technology breakers in....whole different ball game. But have fun doing that. As Max stated, all the fuse or circuit braker does in this case is protect your wiring. And tho they stand a better chance with a fuse or breaker, damage can still occur to the electronics.
[/quote]

Well, that takes away my warm and fuzzy for wanting to run a fuse.  I was even giving some thought to running a manually reset type circuit breaker.

[Bagger]

In July 2009, while my bike was being dyno tuned, my bike experienced a voltage spike that took out the ECM, TSSM, speedometer, passing lamp switch, all the bulbs, Badland Run, Brake and Turn Module, Kuryakyn LED tail lights.  The only plausible explanation is that the circuit breaker overheated and disconnected the circuit from the battery, but not from the alternator, which sent a voltage spike the fried all my electronics.

Did the head light blow??

My bet is that the bike lost the breaker and same time as the head light might have lost connection and the POS badlands brake slight thingy, fed the spike from the running light wiring back into the TSSM, killing the TSSM, ecm and speedo..  after market light thingy.. Leds.. etc...

Mayor You need to read this.. The after market break light / load / turn signal module must have been designed buy a EE that knows reliability...   (or a tech that had engineer's disease)

Max
[/quote]

Yea, the head light bulb blew too.  I run an Azure headlamp with a bulb.

[smoserx1]

In your case, if you get a short in the wire from the battery to regulator, you'll burn that wire and possibly cause a fire.. Max

OK, and thank you.  That does make sense. 

[mayor]

Mayor You need to read this.. The after market break light / load / turn signal module must have been designed buy a EE that knows reliability...   (or a tech that had engineer's disease)

Max

yea, I think it's a vast conspirecy for double E's to take over the world with faulty goods    they must be stopped at all costs

interesting...I'm starting to reconsider whether I will run a brake/turn module again on my efi bike. 

[Admiral Akbar]

In your case, if you get a short in the wire from the battery to regulator, you'll burn that wire and possibly cause a fire.. Max

OK, and thank you.  That does make sense.

Yeah, I grabed the wrong quote,,

That way, if the fuse blows or the breaker trips, you certainly won't get a spike, because both the battery and regulator output would be be instantly disconnected.

This is the one I should have used.. Wasn't trying to pick on Glen,  BTW HarleyinNH seems to have a good setup..

Yea, the head light bulb blew too.  I run an Azure headlamp with a bulb.

There is a bit of the chicken and the egg here.. Technically, the regulator should have stopped the voltage from getting too high.  If you lost the battery connection through the circuit breaker, the rest of the system should be able to run until the Rs drop enough that the alt can't supply power then it shuts down.. The head lamp is part of the load.. If it blew about the same time the breaker let go while the motor was winding up to peak revs. .. The load just got unloaded. With Starting and stopping on the Dyno, the battery voltage was probably low.  During testing so the regulator was WFO trying to charge the battery.. My guess is that it do not respond fast enough to the change in load and the damage cascaded.. Not sure whether it was the after market  TS thing but automotive electronics are generally designed to have an 80 volt spike or more..  If the TS thingy backfed like I was saying it caused the probelm..

You asked me about this Red.. I told you it was improbable.. Now I say it's possible.

Here read this..
http://www.littelfuse.com/data/en/Application_Notes/an9312.pdf

You want to learn about fuses these guys are the ones..

Fuses versus breakers (didn't read it)

http://www.littelfuse.com/data/en/Technical_Articles/Fuses_vs_Breakers_Tech_Topic.pdf

they must be stopped at all costs

Only the primadonna ones.   

Max

[Bagger]

There is a bit of the chicken and the egg here.. Technically, the regulator should have stopped the voltage from getting too high.  If you lost the battery connection through the circuit breaker, the rest of the system should be able to run until the Rs drop enough that the alt can't supply power then it shuts down.. The head lamp is part of the load.. If it blew about the same time the breaker let go while the motor was winding up to peak revs. .. The load just got unloaded. With Starting and stopping on the Dyno, the battery voltage was probably low.  During testing so the regulator was WFO trying to charge the battery.. My guess is that it do not respond fast enough to the change in load and the damage cascaded.. Not sure whether it was the after market  TS thing but automotive electronics are generally designed to have an 80 volt spike or more..  If the TS thingy backfed like I was saying it caused the probelm.

You asked me about this Red.. I told you it was improbable.. Now I say it's possible.

If I remember the events of that tuning day, the tuner was running the bike at WOT, the bike shut down and he smelled smoke, then came out from the tuning booth and brought me in to explain what happened.  The tuner who was also the service manager alleged that it was the Badlands module, the tech that was putting the bike back together thought it was the RB Racing air/fuel ratio gauge that shorted out (gauge face melted pretty good).  Whereas I wasn't in the room and I'm not an electrical engineer, I was left with the dealership not taking responsibility. 

I do remember it was a very expensive day  .  The only positive of the day, Steve Cole covered the cost of a new TTS.  I then bought a used 2005 ECM, TSM and a Kilometer speedometer from the service manager to get me back on the road.

Max good article you posted (Fuses versus breakers)
http://www.littelfuse.com/data/en/Technical_Articles/Fuses_vs_Breakers_Tech_Topic.pdf

[glens]

That way, if the fuse blows or the breaker trips, you certainly won't get a spike, because both the battery and regulator output would be be instantly disconnected.

This is the one I should have used.. Wasn't trying to pick on Glen

I was puzzled too.  Heck, I don't remember anymore, but I thought I'd suggested they connect the alternator wire into the circuit to the normal place through a relay.  It wouldn't melt any more wires between the maxifuse and battery under any condition whatsoever than the stock schematic would.

I don't like it when you pick on me.  My mommy's too far away.

[Ken R]

Why does it need an external reference?

I'm banned so can't see anymore the larger images in http://www.hdtalking.com/electrical/21993-a_peek_inside_a_black_box.html

I'm pretty sure he referenced a second page of schematic but didn't include it for some reason.  I'm going to pull my regulator plug tomorrow and fire up the bike, measuring the output voltage.  I'm betting it'll be less than 15 volts DC.

Boy this thread has grown.  I'll admit to not having read every post yet.  However, someone asked why the 2nd fuse.

If your main circuit breaker (or fuse) blows, it simply disconnects the battery from all of the motorcycles' electronics.  GREAT, you might say.  That would avoid any damaged wiring should a short occur that one of the small fuses couldn't catch (like the main B+ wire under the tank to the ingition switch). 

But, there's a potential problem.  If the fuse (or breaker) blows, the motor is supposed to die.  When the motor dies, the alternator quits producing voltage.  This theory is supposed to protect your motorcycle's wiring from burning.  Fuse blows, disconnecting the battery, motor dies, no more current. 

What it, though, you're at 80 mph and you leave the clutch out?  Motor dies, but is still spinning with the alternator/regulator still producing electrical current at up to 45 amps.  The second fuse I installed is to further protect the motorcycle's wiring.  One should blow.  Then the other one if the over-current problem is still there. 


It should also be noted that HD's fuse (or circuit breaker) breaks the wire between the battery and motorcycle's wiring, leaving the charging system still connected.  The shop manual states that one should never disconnect the battery while the engine is running, else damage to electrical components could occur. 

That's exactly what happend to me 3 years ago and prompted me to design and install the 2-fuse protection system.  My circuit breaker tripped, a voltage spike hit all of the electronic devices.  My breaker tripped and reset several times in the matter of a few seconds.  I was at 50 mph with the clutch out.  Each time it tripped, it produced or had the potential to produce voltage spikes as the battery was disconnected and reconnected each time.  The result was $1,200 in damage to electrical components.  TSSM, Speedo, Tach, Radio, and a few other components were victims of the voltage spike. 

So, I said, "nevermore"; and put in the 2-fuse system.  It has worked flawlessly since.  The 40-amp Maxi fuses have never blown.

[cyrus]

I now would think as a matter of safety there should be a fuse from the voltage regulator.  The wires to the ignition switch and the wires from the ignition switch to the fuse block are not protected. If any of these wires chaffe through and short, they will keep arcing and burning as they are fed by the alternator. You could have a little fire on top off your gas tank! or anywhere in the wire harness that these unprotected wires run.

[Admiral Akbar]

The wires to the ignition switch and the wires from the ignition switch to the fuse block are not protected. If any of these wires chaffe through and short, they will keep arcing and burning as they are fed by the alternator.

Actually, you don't have to worry about this if you size the wire correctly.. The alternator is current limited at what 40-45 amps.. All you have to do is size the wire so that it can handle the current. The main thing you need to worry about is the battery that can put out 10 times the current for a short period of time easy..

Max

[Ken R]

The wires to the ignition switch and the wires from the ignition switch to the fuse block are not protected. If any of these wires chaffe through and short, they will keep arcing and burning as they are fed by the alternator.

Actually, you don't have to worry about this if you size the wire correctly.. The alternator is current limited at what 40-45 amps.. All you have to do is size the wire so that it can handle the current. The main thing you need to worry about is the battery that can put out 10 times the current for a short period of time easy..

Max

The wire seems to be improperly sized, in my opinion.  It is, at best, #12 stranded.  I'm not an electrician, but in house wiring, #12 wire is protected by a 20-amp breaker.  I don't know, it may be rated higher for DC current than AC current.  (defies logic, though).   There is always a measurable voltage drop between the battery and the fuse block, I assume from the resistance of the B+ wire that runs back and forth under the tank. 


I was going to replace the main power wiring with #8 stranded (good for at least 40 amps); even bought wire; but it turned out to be too tough of a job, considering that every Electra Glide is wired the same as mine and they get along just fine.  I scrapped the project. 

[Admiral Akbar]

The wire seems to be improperly sized, in my opinion.  It is, at best, #12 stranded.  I'm not an electrician, but in house wiring, #12 wire is protected by a 20-amp breaker.

Well technically it's not.

http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity

If you look here a 12 gauge wire can handle 41 amps continuous in free air.. The wire can go way higher surges if necessary.   You also see on the table that bundled wire stead state current is way less.

I don't know, it may be rated higher for DC current than AC current.

If you compare RMS current to DC current they are defined as being the same..  The issue is that when you talk watts in an AC system you need to understand power factor which can increase current.. Still 10 amps DC = 10 amps AC (rms).. The big thing is with the sizing of wire in houses is voltage drop.. The supply to your house is that big transformer sitting on the pole down the street.. If you want that microwave to run and still have florescent light working.. You need to size the wire appropriately.

Max