02 Ultra tripping 50 amp main breaker

[Hoople]

I don't see the Maxi on that schematic ?

On this 2002 there is no Maxi Fuse. The resetable circuit breaker takes the place of the Maxi. Note the position of the battery feed and the voltage regulator feed. With the engine off, all the current is supplied by the battery which goes directly through the CB. But when the engine is running, some of the current needed is supplied by the regulator which does not go through the CB. So it really should not be getting Hot which was pointed out by 03Ultra.

Here is late model 2009 using a Maxi Fuse just to compare..

 

[R_W_B]

On this 2002 there is no Maxi Fuse. The resetable circuit breaker takes the place of the Maxi. Note the position of the battery feed and the voltage regulator feed. With the engine off, all the current is supplied by the battery which goes directly through the CB. But when the engine is running, some of the current needed is supplied by the regulator which does not go through the CB. So it really should not be getting Hot which was pointed out by 03Ultra.

Here is late model 2009 using a Maxi Fuse just to compare..

Oh ok, and yes I see what you mean on the Regulator pumping current straight to grd. But I'm still a bit hazy on what's causing it to heat up. Ultra said a loose or rusty connection. Seems that would cause less current flow and less heat, unless it was feeding an induction load like the starter, were the heat (current) would rise due to the voltage drop of the bad connection ?

Anyhow I'm following along again thanks for the clearing up where the maxi was.

Hey nice colored schematics, looks like one of the Haynes manuals.

 

[Hoople]

But I'm still a bit hazy on what's causing it to heat up. Ultra said a loose or rusty connection. Seems that would cause less current flow and less heat

The small resistance of a poor connection converts to heat quickly especially when a bunch of current is flowing. Here is an example to look at. Lets say we have a source voltage of 12 volts (the battery). Lets also say the nominal current the bike uses (running with lights on) is 24 amps (which is realistic). That would mean that the "load" the battery sees has a resistance of .50 ohms (24 divided by 12 = .50)

Now lets say the CB or the poor connection is the equivalent to just .01 ohms (1/100 of 1 ohm which is very small however you look at it). But this load is in series with the main primary load. That means the total load the battery sees is actually broken down into two separate loads which are .49 ohms & .01ohms.

Knowing that we can compute the voltage drop across each load (the .50 ohm and the .01 ohm). The voltage drop across the CB is 24 X .010 or .24 volts. The voltage drop across the .49 ohm load becomes 24 X .49 or 11.76 volts. (As a cross check 11.76 + .24 = the source voltage of 12.0 which is Good!

Now that we know the voltage drop across the CB, we can compute the dissipated wattage which is .24 X 24 or 5.76 Watts. For a silly poor connection, that is a bunch. If you ever placed your finger on a 5 watt resistor at full dissipation, it is hot and it will burn your finger.

Remember this example was based on the source voltage being only 12 volts which we know is not true. We know it's more like 13.5 which would make the end result higher.

In a real world example, I would say seeing 10 watts across a corroded CB breaker would not be too far fetched. Hope this helps..

 

[R_W_B]

The small resistance of a poor connection converts to heat quickly especially when a bunch of current is flowing. Here is an example . . . . . . .

Uh well I think I understand what you are saying. But didn't you mean to type 12 divided by 24 instead of 24 divided by 12 ? I=24, V=12, R= V/I or 12/24 = 0.5 R

The rest I will have to study a bit since I don't want to blog up the OP's thread. If you want to PM me I'm still out to lunch on how the voltage drop across the bad connection is causing anymore total watts other than stealing some from the line thru the bad connection, i.e. if 0.24 x 24 = 5.76w stolen and 11.76 x 24 = 282.24w remaining in the line.
But wouldn't you have the same total even with a good connection that did not steal the 5.76 from the line ? 12 x 24 = 288w same as 282.24 + 5.76 = 288w. But if you're busy, don't bother with it cause my old brain tends to get confused easy on some stuff like this.

I hope the OP does reply back on when he finds out though cause it would be interestin to know.

 

[Hoople]

But didn't you mean to type 12 divided by 24 instead of 24 divided by 12 ? I=24, V=12, R= V/I or 12/24 = 0.5 R

Excellent! Yes, there are probably a couple of typo's within the post. Some are by mistake. Some are not. It tells me if your really reading or just skimming over.what I write.

The post did not take a turn off topic. This info can be applied directly to the original post. In theory we want the CB to remain at room temp when all is good. But if the CB is getting hot, something is wrong (too much current, poor connection, defective CB etc). I personally would not have them on my bike. They were a poor choice of protection to start with and should be replaced with Bussman Cooper Maxi Fuses. HD says to uplift it to 50 amps. That just compounds a bad idea to start with.

So your question. => "But wouldn't you have the same total even with a good connection that did not steal the 5.76 from the line?". Yes you would. The total taken from the battery would have been the same. But that little bit stolen by the CB is being wasted in the form of heat energy. Instead it should have made the headlight just a little bit brighter. (2/10's of 1 volt brighter)

Always fall back on the fact that energy can not be destroyed or created out of thin air and only converted to another form. The poor connection has resistance and therefore will require energy to push current through it. Since the CB has no filament, it can't convert the electrical energy into light energy. Since the CB has no magnets, it can't be an electric motor (mechanical energy). So the easy thing to become is a toaster or heater.

 

[R_W_B]

. . . . . .
So your question. => "But wouldn't you have the same total even with a good connection that did not steal the 5.76 from the line?". Yes you would. The total taken from the battery would have been the same. But that little bit stolen by the CB is being wasted in the form of heat energy. Instead it should have made the headlight just a little bit brighter. (2/10's of 1 volt brighter) . . . . . . . . .

Oh yes I see it now, the filament just lit in my brain and that's dangerous at my age LOL. See I was kinda visualizing it as total amps causes the same heat on the entire line. In other words it's the same heat I speak of that radiates down the line and makes the fuse or breaker trip.

But you've made me realize that it's not really that way (entirely) since some of that heat can be transferred through the bad connection and not even make it thru the breaker. Or at least I think that's what you said.

This is the part of electricity that I've always been weak on. When I first got out of the Army I worked as an apprentice electrician for a few years before I went back to regular construction work. I later wired my entire home by myself from scratch many years ago and it still works with no fires LOL. But I have never really got under the various transformations that current goes thru in cases like this.

I thank NEWHD74FAN, 03ultra and you for helping me to see a bit more down the road on this one.

 

[Big John 57]

Looks like I may have finally found my problem. I checked ohms, amps, checked if voltage going to frame, no problems. By this time I have most of the bike taken apart. Like I said earlier I am not the best at an electrical problems I have to call a friend to ask questions as I am checking different issues. Well he finally just came over today and found a problem I over looked. The terminal looked good on the 50 amp breaker but a few of the wires were broken cut back the terminal put on a new one ran bike and the breaker did not heat up. That breaker was getting as hot as 165 degrees, now not even warm. Hopefully this will end the problems of the tripping 50 amp main breaker.

 

[HDDon]

I'm like you Big John when it comes to electrical problems. We all need a friend like Hoople or your friend. Glad the problem seems to be found and repaired. Ride safe.

 

[R_W_B]

Looks like I may have finally found my problem. I checked ohms, amps, checked if voltage going to frame, no problems. By this time I have most of the bike taken apart. Like I said earlier I am not the best at an electrical problems I have to call a friend to ask questions as I am checking different issues. Well he finally just came over today and found a problem I over looked. The terminal looked good on the 50 amp breaker but a few of the wires were broken cut back the terminal put on a new one ran bike and the breaker did not heat up. That breaker was getting as hot as 165 degrees, now not even warm. Hopefully this will end the problems of the tripping 50 amp main breaker.

Hmmm that was wire(s) plural. Sounds to me like you had a slight short wire to wire on that non fused line (other than the main CB which was trying to do it's job). Now that would definitely cause some heat. Glad you found it and thanks for updating us.

 

[Big John 57]

Thanks guys for helping guide me through this problem. Look forward to reading other blogs on this forum. Keep it real, I am ready for Myrtle Beach Spring Bike Rally!!!!!!!!!!!!!

Big John 57
02 Ultra Classic