kubota b2400 dynamo

[nfisheremti]

my 1996 b2400 dynamo (that's what kubota calls it) no longer can keep up with my nighttime lighting (all LED - only 20W total). if i run in the dark for more that 2hrs, i start loosing LEDs and the tractor doesn't have enough juice left to start again, without sitting on a charger for a few hours (or a jump). my question is this: can i use an aftermarket alternator, or do i need the tiny and expensive kubota one? has anyone tried this? what advice do you have?

thanks.

 

[currierej]

my 1996 b2400 dynamo (that's what kubota calls it) no longer can keep up with my nighttime lighting (all LED - only 20W total). if i run in the dark for more that 2hrs, i start loosing LEDs and the tractor doesn't have enough juice left to start again, without sitting on a charger for a few hours (or a jump). my question is this: can i use an aftermarket alternator, or do i need the tiny and expensive kubota one? has anyone tried this? what advice do you have?

thanks.

My Shibaru was having major electrical problems, I parked it in the garage and proceeded to remove every wire that I could find, front to back.
I rebuilt and rewired the instrument panel, put a new fuse block under the hood, replaced all the lights with LEDs and got rid of the original alternator (the magic smoke had leaked out) and replaced it with a single wire alternator.
Other than making sure that it was turning the correct direction, the biggest thing about changing the alternator was it was slightly larger and I had to weld about a 2" extension to the adjustment bracket and get a slightly longer V-belt.
I went from lots of electrical problems to none....and had fun doing it.

 

[nfisheremti]

thanks. there's space for a bigger unit, but i would have to make a new bracket for it depending on what i get.

 

[currierej]

thanks. there's space for a bigger unit, but i would have to make a new bracket for it depending on what i get.

I took my old smoked alternator to a local car shop and told them that I wanted a single wire unit, he glanced at it, walked to the shelves and grabbed a box.
Not sure what the old one was, but the new one is 60 amp, other than the lights and charging the battery there is no load, so the 60 amp is almost overkill.

 

[currierej]

I took my old smoked alternator to a local car shop and told them that I wanted a single wire unit, he glanced at it, walked to the shelves and grabbed a box.
Not sure what the old one was, but the new one is 60 amp, other than the lights and charging the battery there is no load, so the 60 amp is almost overkill.

I took the tensioner bracket and I had to add about 2" to the end that bolts to the tractor, I then mounted the new alternator and adjusted it to the shortest position, I ran a string around the pulleys and marked the length, went to the auto parts store with the old belt and the string, the new belt fit perfectly- easy-peasy

 

[nfisheremti]

great. i don't know what the wiring on mine is. by 'single wire' you mean it's grounded through it's chassis to the engine (as opposed to grounded through it's wiring harness)

 

[WranglerX]

Remove inadequate "dynamo" and replace with "single wire alternator".... Some wiring revamping will probably be necessary ...

Dale

 

[nfisheremti]

thanks. does anyone have a wiring diagram for this little beast? it's always easier hacking these things if i know where the other end of the wire goes

 

[WranglerX]

great. i don't know what the wiring on mine is. by 'single wire' you mean it's grounded through it's chassis to the engine (as opposed to grounded through it's wiring harness)

Probably ... "One wire" generally mean one terminal/wire going to battery/electrical system... Ground is assumed(bad term) through chassis...

This may help...



Ripped from ...

B1700,%20B2100,%20B2400%20WSM%20Part%202.pdf

Dale

 

[currierej]

Probably ... "One wire" generally mean one terminal/wire going to battery/electrical system... Ground is assumed(bad term) through chassis...

This may help...

View attachment 590682

Ripped from ...

B1700,%20B2100,%20B2400%20WSM%20Part%202.pdf

Dale

The single wire alternator that I have is just that, one single wire runs from the alternator to the positive side of the battery, the voltage regulator is built into the alternator and it does not need any input power to excite the field.
If your alternator has a wiring harness going to it you probably have an external voltage regulator.
Also, if you have an alternator idiot light there is a way to hook it up, but I didn't bother, when I rebuilt the dash I added a voltage gauge.

 

[nfisheremti]

thanks. it appears that i might have a harness (i guess i'll need to pop the hood when it's light outside). from that diagram by dale (thanks very much BTW), i see the dynamo goes straight to the regulator, consisting of a wheatstone bridge. the charge lamp doesn't light up anymore (it did when i was running halogen lights), i remember trying to test the alternator, when i changed out my lighting, and i got 13v which seems low, but should be enough to charge. i wonder if the charge light has burned out. anyway, thanks. i'll tear into it this weekend and see what i can find.

 

[WranglerX]

thanks. it appears that i might have a harness (i guess i'll need to pop the hood when it's light outside). from that diagram by dale (thanks very much BTW), i see the dynamo goes straight to the regulator, consisting of a wheatstone bridge. the charge lamp doesn't light up anymore (it did when i was running halogen lights), i remember trying to test the alternator, when i changed out my lighting, and i got 13v which seems low, but should be enough to charge. i wonder if the charge light has burned out. anyway, thanks. i'll tear into it this weekend and see what i can find.

Check the lamp some systems actually require a operating charge lamp to initiate the charge sequence of alternator systems but as you have a dynamo I suspect its a "generator" it may not need the lamp, but check it anyway... One never knows....

Functioning generator or alternator should top out about 13.8 to 14.2 volts... 12.5 to 13.5 volts is just battery float voltage, doe snot indicate charge..

And in regulator its a "full wave bridge rectifier" (by diagram) and not Wheatstone bridge....

Dale

 

[number two]

See your dealer for an alternator conversion kit about 200 bucks
Good Luck

 

[nfisheremti]

Check the lamp some systems actually require a operating charge lamp to initiate the charge sequence of alternator systems but as you have a dynamo I suspect its a "generator" it may not need the lamp, but check it anyway... One never knows....

Functioning generator or alternator should top out about 13.8 to 14.2 volts... 12.5 to 13.5 volts is just battery float voltage, doe snot indicate charge..

And in regulator its a "full wave bridge rectifier" (by diagram) and not Wheatstone bridge....

Dale

thanks dale, i stand corrected. obviously something is wrong. i'm pretty sure i've totally killed the battery at this point, and i'll need to replace that too. i was hoping to make it through the winter without having to replace anything expensive (i use the tractor with a 60" farm king snowblower on the back to clear about 20 driveways in my neighborhood), margins are tight (maintenance is my largest expense), and nighttime operation is a must.

sorry number 2, i'm balking at $165 for a straight replacement of the dynamo from kubota, and i'm wondering if i can get away with a $50 one off ebay or amazon, or something automotive from a junkie.

 

[WranglerX]

Look around locally to see if you have a industrial/electrical repair facility that services fork lifts and diesel trucks and such ... They used to be around in many places before we became a "throw away' society....If you can find one remove "dynamo" and regulator and take it in to see if they can test it... Check phone book for "automotive electrical services"...

Did a real quick search at GOOGLE SHOPPING and this is what first came up....

https://www.dbelectrical.com/produc...iEbGJo7rul9RwACK0_3pcwsSW73BrcCRoCUMYQAvD_BwE

OR maybe..

NEW ALTERNATOR for CHEVY MINI DENSO STREET ROD 1-WIRE 35 AMP 4-5262 1218-SE | eBay

If your tractor is similar to mine, all it does is charge battery and run lights....Not to much electricals...

Also would put something like this in dash to monitor things

DC 12V-24V LED Panel Digital Voltage Volt Meter Display Voltmeter Motorcycle Car | eBay

Not endorsing any particular one, just to show you don't have to spend a ton of money....

Biggest issue may be modding brackets to make it fit....


Dale

 

[Dave M7040]

thanks. it appears that i might have a harness (i guess i'll need to pop the hood when it's light outside). from that diagram by dale (thanks very much BTW), i see the dynamo goes straight to the regulator, consisting of a wheatstone bridge. the charge lamp doesn't light up anymore (it did when i was running halogen lights), i remember trying to test the alternator, when i changed out my lighting, and i got 13v which seems low, but should be enough to charge. i wonder if the charge light has burned out. anyway, thanks. i'll tear into it this weekend and see what i can find.

Remember, what you have is a dynamo. Permanent magnets rotating around a coil(s) of wire. To test, you need to disconnect wiring at dynamo and measure alternating current voltage. It should be approx 40 volts between each pair of wires if your dynamo has 3 wires.

They are very simple and rarely fail. The rectifier/regulator is a different story as far as reliability is concerned. Rather than change the dynamo's output, the rectifier dumps excess current by converting it to heat. In the beginning, as you converted to LED lighting, you reduced the current draw by the tractor and require the rectifier to dump increased current and you may have cooked it.

Dave M7040

 

[nfisheremti]

interesting thought, but what was kubota thinking when they allow you to not turn any lights on? i would think the rectifier would be designed to dump all of that heat and then some. but certainly checking the voltage regulator is a good idea.

i would think if i disconnected the battery, jumped the tractor and measured the voltage to the battery leads, i should get the 13.8 to 14.2 that dale mentioned above. i suspect i won't but that would test the dynamo and the regulator at the same time. then if i pull the dynamo and bring it to someone to test, if that works, then i must be the regulator right?

 

[Dave M7040]

interesting thought, but what was kubota thinking when they allow you to not turn any lights on? i would think the rectifier would be designed to dump all of that heat and then some. but certainly checking the voltage regulator is a good idea.

i would think if i disconnected the battery, jumped the tractor and measured the voltage to the battery leads, i should get the 13.8 to 14.2 that dale mentioned above. i suspect i won't but that would test the dynamo and the regulator at the same time. then if i pull the dynamo and bring it to someone to test, if that works, then i must be the regulator right?

Test the dynamo. It is simple. If you do not have a multi meter, spend $10 on a cheap one and I will show you how to test the dynamo.

The dynamo is not something you fix as there are so few "fixable" parts unlike an alternator or generator. They rarely fail.

This test for the dynamo is from John Deere just because it is very easy to understand.

Connect voltmeter, set to read AC voltage, to alternator
outputs (B).
5. Start and run engine at fast idle. The meter should read
a minimum of 40 volts AC at FAST idle (3250 rpm).
Results:
• If reading is BELOW specification, test alternator.
Specifications:
Slow Idle (1400 RPM) . . . . . . . . . . . . . . . . . . . . . . .32 VAC
Fast Idle (3250 RPM) . . . . . . . . . . . . . . ..................50 VAC


Dave M7040

 

[nfisheremti]

i do have a meter. i'll give that a try. does anyone know what they are for a kubota b2400? i red line right around 3k. thanks.

 

[Dave M7040]

i do have a meter. i'll give that a try. does anyone know what they are for a kubota b2400? i red line right around 3k. thanks.

Download the WSM for free at:
Index of Kubotabooks/Tractor Owners Manuals/
The WSM is in two parts. The electrical section is in part 2.
This is from the WSM

The test meter is set to alternating current voltage.

Dave M7040