http://www.ebay.com/itm/181473581583Not charging at all, does not require a tester. A simple handheld digital voltmeter can easily spot voltage regulator malfunction.But howabout "Is it good or bad?" maybe issues.Th3 3 volt "ALTERNATING CURRENT" full scale on this voltmeter finds stator problems and rectifier problems in a flash.Take meter out of shipping box.Two wire connections to this meter. Three foot 18 gauge wire is enough. Buy a couple of alligator clips.Clip any of the two wires to negativeTouch the other wire lead to the battery stud on the alternatorHigher than 1 volt on the 3 volt scale means there is a problem inside the alternator. Time to get a replacement.Works on all alternators that are attempting to charge. You know how to tell if the alternator is totally dead, right? This will detect borderline "it's charging a little but not enough" grade problems.

:) Hi, the easiest generator/alternator test is to start the engine and disconnect the negative battery cable; If the engine shuts off the charging system is not working.

Absolutely not recommended and strongly so.GOOGLELOAD DUMPSecond negative to cable disconnect testing...An open or short in a stator winding or in the rectifier bridge will cause PARTIAL charging. Well above the minimum needed to keep an engine running "with a battery disconnect"And THAT is exactly what this cheap tester does for a living - tests for stator and rectifier faults. A burned stator or compromised rectifier is a death rattle for the alternator. Want to find a problem now, or in heavy traffic?I was sitting in Celso's shop when a customer lifted a battery cable on a 2008 Ford Focus. "See the engine died" he said. He blew the ECU. He did not have the 300 dollars to buy a rebuilt computer. The last I saw of the car it was gathering dust. I am still puzzling why he thought he had a problem when the engine kept running with the battery disconnected. The genius had to have done it before and somehow rationalized it was a sign of a problem.What I wrote is not myth or hype. Sometimes an ECU can withstand a LOAD DUMP. Do you feel lucky? Some ECU's cost a thousand dollars and involve a several week wait. Did I discuss ignition key code reset fees? Or multiple ECU CHASSIS PROCESSOR failure?Please do yourself a favor and forget suicide theory. The cost of the meter is dead cheap. Using it is 4th grader complicated and you an impress the first person who you diagnose.The test must be conducted AT THE ALTERNATOR and not anywhere else in the system.

Are you saying to disconnect the vehicles wire(s) that are terminated at the alternator stud prior to connecting a 3v meter? Wouldn't it fry the 3v meter to expose it to 12-14v battery voltage through the harness?

A Ripple test only requires a DMM to check AC voltage. Over 0.5vac = bad diodes in the alternator.Aside from the obvious testing of VDC to make sure it is charging, of course.

A DIGITAL METER does not have a fast enough sampling (refresh) rate to capture ripple peaks. This comes from experience not hypothesis. A .5 ripple proves nothing with the rectified WYE type modern alternators (8 rectifiers) example: Ford, 3, 4, 6G models. Lose the 2.2uf capacitor within the alternator and that .5 ripple limit will have you purchasing an alternator. ND, Mitsubishi, Delco - all he newer (read motorhome) alternators except for "some" Delphi models are 8 rectifier alternators.The test is incredibly easy to performThe meter is incredibly inexpensiveThe meter is incredibly easy to wire with 2 little wires and two strong alligator clips.THERE IS NO CONNECTION POLARITY TO OBSERVE. You cannot connect it "backwards"Connect meter to alternator output stud and to chassis negative (ground) start engine. If that needle swings upward off of zero you have a problem. I suggest SAMPLING some good alternators and get a feel for this critter if you are unsure or have doubts about testing efficacy. The analog meter test is virtually foolproof.

Make Your Own Alternator Tester Cheap & Simple | Good Sam Community

12 Replies

MEXICOWANDERER
Explorer
Aug 12, 2017
Absolutely not recommended and strongly so.

GOOGLE

LOAD DUMP

Second negative to cable disconnect testing...

An open or short in a stator winding or in the rectifier bridge will cause PARTIAL charging. Well above the minimum needed to keep an engine running "with a battery disconnect"

And THAT is exactly what this cheap tester does for a living - tests for stator and rectifier faults. A burned stator or compromised rectifier is a death rattle for the alternator. Want to find a problem now, or in heavy traffic?

I was sitting in Celso's shop when a customer lifted a battery cable on a 2008 Ford Focus. "See the engine died" he said. He blew the ECU. He did not have the 300 dollars to buy a rebuilt computer. The last I saw of the car it was gathering dust. I am still puzzling why he thought he had a problem when the engine kept running with the battery disconnected. The genius had to have done it before and somehow rationalized it was a sign of a problem.

What I wrote is not myth or hype. Sometimes an ECU can withstand a LOAD DUMP. Do you feel lucky? Some ECU's cost a thousand dollars and involve a several week wait. Did I discuss ignition key code reset fees? Or multiple ECU CHASSIS PROCESSOR failure?

Please do yourself a favor and forget suicide theory. The cost of the meter is dead cheap. Using it is 4th grader complicated and you an impress the first person who you diagnose.

The test must be conducted AT THE ALTERNATOR and not anywhere else in the system.
ROBERTSUNRUS
Explorer
Aug 12, 2017
:) Hi, the easiest generator/alternator test is to start the engine and disconnect the negative battery cable; If the engine shuts off the charging system is not working.

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Make Your Own Alternator Tester Cheap & Simple

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