Author Topic: How I test the Charging System  (Read 232 times)

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Offline Art

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How I test the Charging System
on: 22 November, 2021, 06:16:01 AM
How to test the charging system, battery, wiring, stator and regulator/rectifier here's how I do it all in one place. First some myths. A flashing ABS warning light + flat battery + engine cutting out doesn’t prove that the stator has failed, the fault may be elsewhere and further tests are required. The Honda factory fitted regulator/rectifier doesn’t need to be replaced unless it is proven to be faulty, nor does it need to be upgraded to a MOSFET regulator/rectifier, the original regulator/rectifier is a MOSFET unit!

If you suspect a charging system fault prove it! The charging system should be tested in the following order - battery, charging system output, wiring, stator. The procedures here are mostly explained in the Honda and Haynes Workshop Manuals and in ElectroSport's Fault Finding Flow Chart. If you haven't already you can download the Honda Workshop Manual here and the ElectroSport Fault Finding Flow Chart for motorcycle charging systems here

Here are my idiot guides and how I do it, select the 20v DC range on the multimeter…

Test the battery

With the Ignition switched off the battery's level of charge, voltage across the battery terminals, should be 12.4v or greater. If the level of charge is less than 12.4v then fully charge the battery, switch the headlamp on for one minute to get rid of any surface charge, re-check the battery's level of charge to be sure it has more than 12.4v and that it is holding that charge. If the battery fails to hold 12.4v or more replace the battery.

Test the charging system output

With the engine idling at 1,200 RPM check the voltage across the battery terminals, expect more than 12.0v. Rev the engine to 2,500 RPM and check the voltage across the battery terminals, expect greater than 13.5v. Rev the engine to 5,000 RPM and check the voltage across the battery terminals, expect less than 15.5v. If the charging system is producing more than 13.5v at 2,500 RPM and less than 15.5v at 5,000 RPM it is OK. If the charging system is producing more than 15.5v at 5,000 RPM the regulator/rectifier is faulty. If the charging system is producing less than 13.5v at 2,500 RPM suspect the stator but further testing is required to prove the fault.

Test the wiring

1) With the ignition switched on but the engine not running check that the voltage across the regulator/rectifier red and green output cables is equal to the voltage across the battery terminals.

2) Connect the black multimeter probe to the battery positive terminal, connect the red multimeter probe to the regulator/rectifier red output cable, with the engine idling on tick over at 1,200 RPM expect less than 0.2v. If greater than 0.2v disconnect, clean and check all terminals and connections in the positive cable between the regulator/rectifier and the battery positive terminal, including the main 30A fuse connections. Then repeat the test to prove the regulator/rectifier positive output wiring to the battery positive terminal is good.

3) Connect the red multimeter probe to the battery negative terminal, connect the black multimeter probe to the regulator/rectifier green output cable, with the engine idling on tick over at 1,200 RPM expect less than 0.2v. If greater than 0.2v disconnect, clean and check all terminals, connections and chassis ground points in the negative wiring between the regulator/rectifier, chassis grounds and the battery negative terminal. Alternatively splice a 27A ground cable into the green cable on the loom side of the regulator/rectifier connector and run this direct to the battery negative terminal. Repeat the test to prove the regulator/rectifier negative output wiring to the battery negative terminal is good.

Test the stator

1) Disconnect the stator to regulator/rectifier three pin white connector and test for continuity between any one of the three yellow output cables from the stator and chassis ground or the battery negative terminal. Expect no continuity, if there is continuity that means one or more of the stator coils has burnt out and the stator will need replacing or rewinding.

2) Select the 200Ω range on the multimeter and test the resistance between each pairing of the three yellow output cables from the stator. Expect three equal readings in the range 0.1Ω to 1Ω, if any readings are outside this range the stator is faulty and will need replacing or rewinding.

3) Select the 200v AC range on the multimeter and with the engine running at 5,000 RPM test the stator output voltage between each pairing of the three yellow output cables from the stator. Expect three equal readings of 40v AC or more, if the readings are not equal or less than 30v AC the stator is faulty and will need replacing or rewinding.

Testing the regulator/rectifier

All the home mechanic can do to test the regulator/rectifier is to test the diodes and the charging system output voltage. If the charging system output voltage, as tested above, is within specification there is no point in testing the diodes and the regulator/rectifier can be assumed to be good.

 


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