My thought was the smoke of molten insulation getting sucked into the air intake probably didn't help the engine make full power.
Positive Battery Cable Melted
- Thread starter TailBent
- Start date
I am thinking the alternator was trying to keep up with the draw of the battery.
If on the switched side of the battery a wire was shorted to ground would cause the battery positive to go to ground. If that happened the alternator would try to supply the current needed. This would put a big load on the engine trying to keep the alternator working.
After a load like this I would test the alternator as well to make sure you didn't blow the diodes out.
Just a SWAG but it is my SWAG(-;
If on the switched side of the battery a wire was shorted to ground would cause the battery positive to go to ground. If that happened the alternator would try to supply the current needed. This would put a big load on the engine trying to keep the alternator working.
After a load like this I would test the alternator as well to make sure you didn't blow the diodes out.
Just a SWAG but it is my SWAG(-;
Quite a variety of opinions and theories on this one. Most (including this one) will probably prove to be wrong. Anyway, here's my take on it.
Other than a battery and a cable, there's nothing else wrong with the electrical system. The original post states the cable melted 3/4 of the length from the positive battery post down. My guess is the cable insulation wore through at that point, grounded out, and the fireworks began. The bulk of damage done was confined to that.
The loss of power while dragging his load could easily have been something other than electrical in nature. He doesn't run it all that much by his own admission. Why can't something fuel/supply related be considered as well? We're not talking about a big tractor. How much load would it take to bog down a twenty horsepower three cylinder engine?
I don't have a B7500 in front of me to study, but have been around tractors long enough to know that simultaneous symptoms aren't always connected or inter related. Perhaps when the tractor is up and running again there will be more to learn. Let's wait til that happens and we find out who (if anyone) was right.
Other than a battery and a cable, there's nothing else wrong with the electrical system. The original post states the cable melted 3/4 of the length from the positive battery post down. My guess is the cable insulation wore through at that point, grounded out, and the fireworks began. The bulk of damage done was confined to that.
The loss of power while dragging his load could easily have been something other than electrical in nature. He doesn't run it all that much by his own admission. Why can't something fuel/supply related be considered as well? We're not talking about a big tractor. How much load would it take to bog down a twenty horsepower three cylinder engine?
I don't have a B7500 in front of me to study, but have been around tractors long enough to know that simultaneous symptoms aren't always connected or inter related. Perhaps when the tractor is up and running again there will be more to learn. Let's wait til that happens and we find out who (if anyone) was right.
Makes sense. I was thinking about the starter motors that the solenoid also extends the starter pinion.Good theory, but very unlikely.
This could only happen if the solenoid was stuck, otherwise the starter to battery connection is cut when you cut power feeding the solenoid.
So no backfeed could happen even if the starter did manage to get stuck in the engaged position.
If... the solenoid arced and stuck open, the spinning engine would still be able to disengage from the pinion.
Your garden variety cut insulation and massive short is probably right.
Thaks to everyone that replied.
The charger is actually a maintainer, my bad choice of word. Led's that show battery status, etc. I keep one on a Kawasaki mule and a DR brush mower, same 10 month absence, no problem. The K ran for 20 minutes before meltdown. Possible it started at the place where the the cable made the turn to enter the passage at the frame, and melted toward the battery, which might explain the way it acted before I turned it off. The battery melted at the positive terminal, I lifted it out, and put it back in and the battery buzzed, still good charge.
I think I will get a new Kubota cable, and my oldest "ready to fail" battery from another implement, and try it again, watching and monitoring the cable temperature carefully. If I'm lucky, it was battery or cable failure. If I'm not lucky, its time for the K to visit the dealer for other maintenance anyway.
Problem is in the heart of the Texas hill country there is only one dealer that will get to it in under a month and he is 25 miles away. Glad I put an electric winch on the Mule or I couldn't get the tractor on the trailer.
Its hard being an urban 'rancher'. Not a lot of hours on the equipment, but a lot of time on the batteries, hoses carburetors, etc. Spend most of my time there maintaining equipment, but wouldn't change anything. I love it.
The charger is actually a maintainer, my bad choice of word. Led's that show battery status, etc. I keep one on a Kawasaki mule and a DR brush mower, same 10 month absence, no problem. The K ran for 20 minutes before meltdown. Possible it started at the place where the the cable made the turn to enter the passage at the frame, and melted toward the battery, which might explain the way it acted before I turned it off. The battery melted at the positive terminal, I lifted it out, and put it back in and the battery buzzed, still good charge.
I think I will get a new Kubota cable, and my oldest "ready to fail" battery from another implement, and try it again, watching and monitoring the cable temperature carefully. If I'm lucky, it was battery or cable failure. If I'm not lucky, its time for the K to visit the dealer for other maintenance anyway.
Problem is in the heart of the Texas hill country there is only one dealer that will get to it in under a month and he is 25 miles away. Glad I put an electric winch on the Mule or I couldn't get the tractor on the trailer.
Its hard being an urban 'rancher'. Not a lot of hours on the equipment, but a lot of time on the batteries, hoses carburetors, etc. Spend most of my time there maintaining equipment, but wouldn't change anything. I love it.
I will keep this thread updated when I solve the problem. But it will be sometime in April or May. Not there to work on it now.
I really appreciate everyone's input.
I really appreciate everyone's input.
The theory of the starter being driven by the engine energizing and over-supplying the electrical system is a red herring. Impossible under even the wildest imagination. If the starter remained engaged with the flywheel (highly unlikely) it would in only a moment become wildly over-sped and the armature would disintegrate from centrifugal forces beyond it’s design.
THAT might create a heck of an electrical short but it would be quite evident and the starter would never work again.
The theory that the alternator somehow “overpowered” the electrical system is also a red herring. For one thing, the regulator would shut the alternator down to prevent that. For another thing, the alternator on most of these Kubotas are rated at 40-60 amps and the battery cable is rated at 400-600 Amps.... so the alternator could never overheat a battery cable even if it’s internal regulator failed.
Using automotive-rated batteries in agricultural equipment works most of the time but purpose-designed batteries are designed for the rough off-road vibration that automotive batteries are not. This is to prevent plate damage from bumps and grinds and they usually also have permeable membrane separators between plates to preclude electrical-shorts across plates (which is what likely happened in this discussion scenario, IMO>)
THAT might create a heck of an electrical short but it would be quite evident and the starter would never work again.
The theory that the alternator somehow “overpowered” the electrical system is also a red herring. For one thing, the regulator would shut the alternator down to prevent that. For another thing, the alternator on most of these Kubotas are rated at 40-60 amps and the battery cable is rated at 400-600 Amps.... so the alternator could never overheat a battery cable even if it’s internal regulator failed.
Using automotive-rated batteries in agricultural equipment works most of the time but purpose-designed batteries are designed for the rough off-road vibration that automotive batteries are not. This is to prevent plate damage from bumps and grinds and they usually also have permeable membrane separators between plates to preclude electrical-shorts across plates (which is what likely happened in this discussion scenario, IMO>)
Something along these lines is entirely possible, but it would be irresponsible to ignore the alternator / voltage regulator. Especially since it can be checked in no time at all once it is all put back together. It is not the current output of the alternator that would cook the battery. It would be the voltage. A battery is nothing more than a swimming pool for electrons. Voltage is the pressure that forces those electrons into the pool. A voltage regulator can fail and the voltage can raise and the battery will boil and swell. I’m sure someone on here has seen this before too. Once it is back together with new battery and cable, check both DC and AC voltage with tractor running. Should be around 14.4VDC and should be 0VAC. Takes literally less than a minute for piece of mind.
It’s not “irresponsible” ... it’s sensible.
And voltage isn’t the issue either. Volts times Amps = Watts (the ability to do work...or damage.)
This means that if volts increase, that amps Must decrease because the finite wattage output of these alternators cannot increase even during mechanical failure.
(And anyone with an oscilloscope will certainly see AC current in this system...but the amperage is so minute it is insignificant for the same reasons already mentioned.)
This is also why you don’t leave it on a trickle charger. Same thing at a few amps or less. Just takes longer.
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
re: ...And anyone with an oscilloscope will certainly see AC current in this system
Please tell me WHERE the AC is coming from. I'm not familiar with Kubota alternators or dynamos.... I've always assumed they were 3 phase alternators, like all the 'car' units.
Please tell me WHERE the AC is coming from. I'm not familiar with Kubota alternators or dynamos.... I've always assumed they were 3 phase alternators, like all the 'car' units.
I’m sure they’re 3 phase as well. 3 phase is AC. It is inevitable that a small amount of this AC will make it past the voltage regulator in the form of a small “ripple”. I suppose if you wanted to study this tiny ripple you could haul out the oscilloscope that everyone has in their toolbox and do so, but checking for AC with a digital meter will suffice. I said 0VAC, but in reality it may show like .050 - .100 VAC (I’m sure there is a spec somewhere). The voltage regulator doesn’t necessarily clean all of this ripple into a perfect flat DC voltage. As long as you don’t see anything appreciable I’m sure it’s OK.
torch
Well-known member
Equipment
B7100HSD, B2789, B2550, B4672, 48" cultivator, homemade FEL and Cab
I had something very similar happen to my truck once. Running some errands and after starting the truck at one store, I noticed a strange noise driving down the road. Pulled over, shut off the truck, and discovered the starter was still spinning the engine over. Pulled every fuse and relay I could find before I realized it was because the solenoid stuck closed. The only way to stop it was to disconnect the battery. It ruined a 1 month old starter motor.
Of course, it could just be that the mice ate the insulation off your cable and it shorted to the frame.
Either way, be very cautious about connecting a fresh battery.
Of course, it could just be that the mice ate the insulation off your cable and it shorted to the frame.
Either way, be very cautious about connecting a fresh battery.
No chance to visit my tractor, no chance to travel right now. Hope the cows haven't lunched on the hydraulic lines the way they have on the electric wires on the trailer.
Still appreciate the input.
Does anyone know what the length and gauge of the positive battery cable is?
Would like to prepare one now that I can't do anything else.
Still appreciate the input.
Does anyone know what the length and gauge of the positive battery cable is?
Would like to prepare one now that I can't do anything else.
I wasn’t suggesting the everyone has an oscilloscope in their toolbox. I was attempting to describe that AC current does exist (however small) and that someone with an oscilloscope could find and demonstrate that .