My Kubota L245DT alternator is overcharging. I took my alternator to a repair shop and was told it is working fine. I also replaced my voltage regulator. Checked ground to battery, looks okay. It's still putting out almost 19 volts when at max RPMs. Any ideas on what could be the problem?
Kubota Tractor Over Charge Problem
- Thread starter Possqually
- Start date
I don't know that tractor, so I can't comment specifically, but generally an overcharge problem is either the regulator (often built into the alternator), or the battery, or a poor connection somewhere in the charging circuit.
Poor connections can be inside a cable, hidden from view. Such a cable might show good continuity with a meter, yet not carry sufficient current to ensure correct operation.
Poor connections can be inside a cable, hidden from view. Such a cable might show good continuity with a meter, yet not carry sufficient current to ensure correct operation.
Check the ground connection. Make sure your alternator is well grounded and the chassis ground connection is "bright and tight". Otherwise, I'd suspect the voltage regulator.
North Idaho Wolfman
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I've seen parts stores with alternator/starter testers pass judgement on alternators that charged over 15V as OK,it's charging!
My money is a bad regulator or poor testing instrument.
Good Luck!
My money is a bad regulator or poor testing instrument.
Good Luck!
Pau7220
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The battery acts as a ”shock absorber” for an electrical system… and if excessively weak or disconnected will allow voltage spikes and high readings. Was it load tested?
North Idaho Wolfman
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Well yes the alternator could be putting out 19V, but it's the output of the regulator, as that is what the battery is seeing.
What is that output voltage?
GBJeffOH
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GreensvilleJay
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If that alternator is externally regulated, then 19 volts would be an acceptable voltage coming from the alternator, assuming is 3 phase DC voltage. The 'regulator' will take 19 volts and reduce to +-14 volts to feed the battery.
There is no such thing as "3 phase DC voltage". DC does not have phases. That is an attribute of AC only.
That is the place to check. If you get a high reading there, try another voltmeter. Still high, check all connections including grounds. Recheck and then, if necessary, replace the voltage regulator which may be inside or outside of the alternator, generator or dynamo or whatever it is called this week.
GreensvilleJay
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multiphase DC is quite common, car alternators are 3 phase. 3 windings, 120* phasing, where the voltage is rectified into DC. You'll see 3 humps usually +12 to +14 volts ,not sinewaves where voltage goes plus AND minus from 0 volts.
You'll also see multiphase DC more commonly referred to PWM, where it's a square wave being generated and not the usual sine wave. Every 'switching power supply' is at least 2 phase DC, large motors run on 6 phase ( 3 phase, bipolar), stepping motors in printers, are typically 2 phase, better are 4 phase. Railguns(fun 'toys' I used to build) can be considered multiphased DC.
BTW the motors that hobby RC 'drones' use are 3 phase DC motors, huge market, millions sold !
AC means Alternating Current, it goes one way then another , whereas DC (Direct Current) ,only flows in one direction.
You'll also see multiphase DC more commonly referred to PWM, where it's a square wave being generated and not the usual sine wave. Every 'switching power supply' is at least 2 phase DC, large motors run on 6 phase ( 3 phase, bipolar), stepping motors in printers, are typically 2 phase, better are 4 phase. Railguns(fun 'toys' I used to build) can be considered multiphased DC.
BTW the motors that hobby RC 'drones' use are 3 phase DC motors, huge market, millions sold !
AC means Alternating Current, it goes one way then another , whereas DC (Direct Current) ,only flows in one direction.
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I was thinking it was 3ph ac too. Up wards of 400 hertz and is changed to dc by the 6 diodes in the diode pack in the alternator. Isn't the out put controlled by the excitation voltage from the regulator thru the slip ring brushes?
It has been a while for me, I might have some of this wrong.
GreensvilleJay
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The external regulator controls the field coil current (strength of the electromagnet that then determines the output current that charges the battery. Some kind of 'feedback' is used to reduce charging current when the battery is fully charged. Originally 'regulators' were external from the alternator due to size/heat limitations.As technology improved, regulators could be installed inside the alternator, the GM DELCO 10SI is probably the best known.
Well…. you are correct, of course…. as this IS AN ALTERNATOR!
It gets rectified with a diode-bridge to output DC.
And therein lies a potential set of issues.
Wiring diagram, study it using the thought, "what if this function doesn't work".
I have [obviously] not worked with this tractor in the past. Rather, older equipment with external regulator/rectifiers. I wrote a deal up on them a while back. In a nutshell, if the reg/rec does not get proper ground or voltage where it needs it, be it from a bad connection in a connector or perhaps failing wiring, the reg/rec will not receive what it needs to, and it won't rectify and/or regulate properly. Many times, they'll just overcharge, typically 18-22v DC measured at the battery. And, they'll cook the battery. With this style, a voltage drop test tells the entire story.