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LT40 Kubota 2 Alternators

Started by flatrock58, July 22, 2021, 03:56:08 PM

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flatrock58

I have been having a few issues with my LT40 and noticed that when both hydraulic pump are engaged and hit their limit it draws down the voltage from 14v (output by the alternator) down to 8-9 v.  Recently  my motor was shutting down when the voltage dropped, which I am assuming that the accuset/or other controllers does not like the low voltage.  After changing batteries and a lead or two the motor is not shutting down, but the voltage measured at the solenoid in the hydraulic box drops down to 8-9 volts still when the hydraulics is maxed out.  

My Kubota motor actually has two alternators.  One is smaller and not used.  I was wondering if anyone had ever hooked up the second alternator.  I would assume it would work and be like a higher output alternator.  Any input would be appreciated.
2001 LT40 Super Kubota 42
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terrifictimbersllc

I never used the small alternator on my 42 kubota. It was just there to tension the belt properly. It isn't needed and I don't think it would offer much extra.

You should not see those low voltages with the proper battery if your alternator is working correctly. LT40 super has a 140 amp alternator and a group 31 Deka AGM battery. I'm pretty sure together these keep the voltage above 11v at maximum amp draw.

I'd  get Woodmizer electrical on the phone and give them your figures and take it from there.




DJ Hoover, Terrific Timbers LLC,  Mystic CT Woodmizer Million Board Foot Club member. 2019 LT70 Super Wide 55 Yanmar,  LogRite fetching arch, WM BMS250 sharpener/BMT250 setter.  2001 F350 7.3L PSD 6 spd manual ZF 4x4 Crew Cab Long Bed

Magicman

You very possibly do not have good contact between your contactor and power strip.  Shine the strip and be sure that your contactor has plenty of adjustment.  Whatever it is, find it to prevent burning your hydraulic pump motors.
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

mike_belben

Whats the resting engine off voltage,  the voltage at idle and the voltage at WOT? 


If it comes up to 13.x or more and has magnetism at the back of the housing from the field flux, its working.  If it sometimes does and sometimes doesnt, id pull the alternator apart.  I will bet the brushes have worn a deep groove in the commutator on the armature shaft..  
Praise The Lord

Ben Cut-wright

I read your voltage tests were taken at TWO points, (1)"14v output by the alternator" and  (2)"solenoid in the hydraulic box drops down to 8-9 volts.  It must be determined if the current source is at fault or the load is excessive.  Obviously, the alternator is capable of making proper voltage, but it (the charging system and circuits) may not be *capable of transmitting current while maintaining voltage. 

Using only voltage as a test result and testing only the engine/saw-head side of the circuit should eliminate the contact strip having too much resistance. Too much resistance at the strip should NOT cause "engine shut-off". It would cause loss of voltage to the pumps. 

If the voltage in the entire electrical system drops dramatically when the pumps are in use this could mean (1) excessively high current demand from the pumps, (2) battery and charging isn't sufficient. Current/amperage tests can determine which one is the case.  Voltmeter tests might show which side, source or load, is at fault.

Two parallel charging sources for one battery is possible, but there CAN be problems with doing that.  My thought is that the engineers would have included the small amount of wiring needed if it would have been beneficial.  Circuit and control devices are available to help ensure such a circuit is protected and operates properly, but....these devices are expensive. 

ladylake



 I wouldn't be running the hyd pumps up against the limits very long.  Hugh amp draw and hard on everything.  Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

mike_belben

i guess i skimmed the first post too fast, bens post filled in the picture better for me. 


Why is woodmizer installing a dead alternator?  Just for a tensioning idler?  


If the alternator is making 13+ vdc at its output lug while some load on the other end is dragging it down to the 8s theres probably a high corrosive resistence somewhere creating the big voltage drop in the circuit.  

 A temp gun could find it if its in the positive wires.  Or chomping on jumper cables for expedient grounds between alternator case and pump case would prove it out if this machine uses steek chassis grounding instead of wire.

Now if the alternator output lug is dropping to 8 its inside the case and id still bet brushes/commutator. Easily visible when disassembled. 

Praise The Lord

Magicman

Quote from: flatrock58 on July 22, 2021, 03:56:08 PMAfter changing batteries and a lead or two the motor is not shutting down, but the voltage measured at the solenoid in the hydraulic box drops down to 8-9 volts still when the hydraulics is maxed out.
I am reading that you have corrected your engine issues and are now only concerned with the low voltage at your hydraulic solenoids. 

If your connection to your power strip is as it should be, the battery voltage and the voltage at the hydraulic pumps should be virtually the same.  If it is not, then look at either the main power solenoid in the metal box or the power strip/contactor.
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

flatrock58

Today I went to check voltages on an LT50 that a friend owns.  On his mill the voltage at the alternator, under load, was 12v, where mine was 11v.  At the power strip and battery, his was 10 v and mine is around 9v now.   I am assuming that the battery positive lead that I changed from a clamp on to a crimped lug might have helped bring up my voltage a volt or so.

I am getting the same voltage at the power strip and the battery and at the solenoid in the hydraulic box.  So there is no loss there.     

I have only been running the pump at there limit of 2200 psi for a moment to see the drop in voltage.  Oddly enough when my motor was dropping out I was not maxing out the pump.  I would just drop out randomly when I used any or the hydraulic functions.  

The voltage with the engine running and when not using the hydraulics is always 14v -14.3 volts everywhere.

I plan on changing out the battery ground clamp with a crimped lug to eliminate corrosion and contact issues with the ground.  

I will also use my temperature gun to see if I find any hot spots in the circuit. 

Thanks for all the input.  It sure is nice to have a place to get ideas from knowledgeable people when problems do arise.  I like my older mill with the Kubota engine, but with its age comes some little problems that are not always easy to diagnose.  
2001 LT40 Super Kubota 42
6' extension
resaw attachment
CBN Sharpener
Cooks Dual Tooth Setter
Solar Kiln

mike_belben

Do these pumps that are drawing all this juice use copper wire for the ground or just steel framework?
Praise The Lord

flatrock58

It is a stranded copper wire to ground  
2001 LT40 Super Kubota 42
6' extension
resaw attachment
CBN Sharpener
Cooks Dual Tooth Setter
Solar Kiln

barbender

The older mills ground the hydraulic pumps through the frame, that's how my '97 is set up.
Too many irons in the fire

Ben Cut-wright

Quote from: flatrock58 on July 23, 2021, 10:32:02 PM
(1) On his mill the voltage at the alternator, under load, was 12v, where mine was 11v.  At the power strip and battery, his was 10 v and mine is around 9v now.   I am assuming that the battery positive lead that I changed from a clamp on to a crimped lug might have helped bring up my voltage a volt or so.

(2) I am getting the same voltage at the power strip and the battery and at the solenoid in the hydraulic box.  So there is no loss there.    

(3) I have only been running the pump at there limit of 2200 psi for a moment to see the drop in voltage.  Oddly enough when my motor was dropping out I was not maxing out the pump.  I would just drop out randomly when I used any or the hydraulic functions.  

(4) The voltage with the engine running and when not using the hydraulics is always 14v -14.3 volts everywhere.

(5) I plan on changing out the battery ground clamp with a crimped lug to eliminate corrosion and contact issues with the ground.  

(6)I will also use my temperature gun to see if I find any hot spots in the circuit.

Thanks for all the input.  It sure is nice to have a place to get ideas from knowledgeable people when problems do arise.  I like my older mill with the Kubota engine, but with its age comes some little problems that are not always easy to diagnose.  
(1) Are the comparison voltages at engine idle?  Those voltages are marginal to unacceptable.  They indicate the alternator has contributed ALL it can at that RPM, or load, and that the battery is now being taxed.  The "one volt" difference between the two mills is more significant than it might appear.
(2) That agrees with your initial posting info.
(3) Hydraulic motor starting amperage most likely was even higher than max load amperage.
(4) That voltage indicates the alternator regulator is operating properly. A full load amperage test would prove the alternator sound.
(5) Cleaning all grounds and eliminating corrosion is good maintenance. 
(6) A "voltage DROP test" will find poor connections instantly, no need to load a circuit until heat builds up, cheap and fast test.   

maple flats

I'll hazard a guess as to why Kubota has 2 alternators. Could be Woodmizer buys a std engine just because they can get it for less than if the engine was custom designed. Woodmizer wants a bigger alternator so they add one without also redesigning the belt tension set up.
logging small time for years but just learning how,  2012 36 HP Mahindra tractor, 3point log arch, 8000# class excavator, lifts 2500# and sets logs on mill precisely where needed, Woodland Mills HM130Max , maple syrup a hobby that consumes my time. looking to learn blacksmithing.

flatrock58

Ben Cut-Wright.  All these measurements were made with the engine idling since it is usually in that state when I have had the problem.  I guess I could check it with the blade engaged to see if there is any noticeable difference.

You are probably right about the starting amps too since a lot of times I would have the motor shut down while the hydraulics were not at the max but when I simply started them.  

When you say a voltage drop test are you talking about testing each line with a voltmeter to see the drop in that line?
2001 LT40 Super Kubota 42
6' extension
resaw attachment
CBN Sharpener
Cooks Dual Tooth Setter
Solar Kiln

flatrock58

maple flats.  You  re correct on having two alternators.  They left the original alternator on so they would not have to modify the pulley arrangement on the Kubota engine.  They added another 140 amp alternator at the other end to handle the hydraulics and such.  
2001 LT40 Super Kubota 42
6' extension
resaw attachment
CBN Sharpener
Cooks Dual Tooth Setter
Solar Kiln

Ben Cut-wright

Quote from: flatrock58 on July 24, 2021, 09:31:51 PM
Ben Cut-Wright.  All these measurements were made with the engine idling since it is usually in that state when I have had the problem.  I guess I could check it with the blade engaged to see if there is any noticeable difference.

You are probably right about the starting amps too since a lot of times I would have the motor shut down while the hydraulics were not at the max but when I simply started them.  

When you say a voltage drop test are you talking about testing each line with a voltmeter to see the drop in that line?
I only asked about to confirm that the engine was at idle.  The battery would very quickly become depleted if those voltages were at engine working RPMs. Can't hurt to test at full RPM to confirm the alternator's ability to handle the load and keep the battery charged properly.

WoodMizer advises that the engine be running to operate ANY heavy electrical loads.

"voltage drop" tests are a unique test procedure which can be used to find connections and wiring having from slight to very poor ability to conduct current. Using direct meter measurements across the entire circuit or any single connection simplifies the method.  Volt drop testing essentially requires the negative (-) lead to contact the most negative *side of the connection and the positive (+) test lead to contact the most positive *side.   Energize the circuit in order to place a load on the circuit. Read volt drop directly off the test instrument.  Good connections will have very low voltage drop. The alternator or battery voltage variance does not correlate to volt drop.

Magicman

Just a note for those reading that may not know, my engine idle speed is 1500 rpm which keeps the alternator at full output at all times.


 
I have a digital voltmeter wired directly to the battery which reads a minimum of 12.7 with the engine off and ~14.4 with the engine running, whether at idle or cutting speed.
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

Ben Cut-wright


There can be NO specific voltage measurement for ALL operating conditions or situations.  Rather, expect a range of acceptable voltages and amperage readings dependent on many factors.

Alternators or generators, the types being discussed here,  operating at "full output at all times" will quickly destroy themselves.  It is safe to assume charging *voltage should be in a range at or near max when loads/amp draw is low. The hydraulic pumps demand MORE *amperage than the alternator can provide at IDLE.  When this occurs the battery supplies a portion of amperage to make up for the shortage.  During this period of circuit load/increased amperage demand the *voltage WILL drop. This is normal and does not condemn the alternator, nor does it prove it sound. 

flatrock58

 

 Magicman  I did copy you and added a voltmeter a while back.  I recently added a temp gauge, after the temperature sensor went bad and the idiot light came on.
2001 LT40 Super Kubota 42
6' extension
resaw attachment
CBN Sharpener
Cooks Dual Tooth Setter
Solar Kiln

terrifictimbersllc

Quote from: Ben Cut-wright on July 25, 2021, 08:30:47 AM

There can be NO specific voltage measurement for ALL operating conditions or situations.  Rather, expect a range of acceptable voltages and amperage readings dependent on many factors.

Alternators or generators, the types being discussed here,  operating at "full output at all times" will quickly destroy themselves.  It is safe to assume charging *voltage should be in a range at or near max when loads/amp draw is low. The hydraulic pumps demand MORE *amperage than the alternator can provide at IDLE.  When this occurs the battery supplies a portion of amperage to make up for the shortage.  During this period of circuit load/increased amperage demand the *voltage WILL drop. This is normal and does not condemn the alternator, nor does it prove it sound.
What do your asterisks mean?
DJ Hoover, Terrific Timbers LLC,  Mystic CT Woodmizer Million Board Foot Club member. 2019 LT70 Super Wide 55 Yanmar,  LogRite fetching arch, WM BMS250 sharpener/BMT250 setter.  2001 F350 7.3L PSD 6 spd manual ZF 4x4 Crew Cab Long Bed

Ben Cut-wright

Quote from: terrifictimbersllc on July 25, 2021, 10:39:15 AM
What do your asterisks mean?
I take the liberty to use them to bring more attention, while at the same time differentiating, the words they punctuate. I apologize if they are distracting from the content of my reply. 
 

Voltage and amperage are separate quantities working together in the electrical circuit, often working inversely to each other.  A single test quantity does little more than *indicate the circuit potential.  If both quantities are used at a specific operational instance, it is possible to make an assessment of the viability of that circuit.


For example, there is little *diagnostic value in knowing the voltage of a circuit if the load/amperage demand or source potential is unknown.  Sure voltage is one indicator or the health of the circuit, but if extreme load is placed on that same *normally designed and properly functioning circuit, the voltage WILL drop.  

Southside

If I watch the control screen on my Super 70 I can see the voltage fluctuate in real time, some functions make it happen more than others but it's not a flat reading by any means.  On that machine the voltage is read through the head ECU and displayed on a computer screen, so it's fast to respond.  Also gives me band FPM in real time along with engine temp, hydraulic pressure, etc. 
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flatrock58

Southside the lt70 sounds nice. Would love all those features. Not going to happen though. Will have to do with what I have!
2001 LT40 Super Kubota 42
6' extension
resaw attachment
CBN Sharpener
Cooks Dual Tooth Setter
Solar Kiln

flatrock58

Well after putting crimp on lugs on both battery cables and checking, cleaning and tightening all connection the voltage on the power strip is only dropping to 11 volts. A big improvement!
2001 LT40 Super Kubota 42
6' extension
resaw attachment
CBN Sharpener
Cooks Dual Tooth Setter
Solar Kiln

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