Uploaded October 2021 | Updated September 2026, 30 minutes ago
There are three main sections to the charging system on most bikes (excluding the wiring inbetween). Those are the Battery, Regulator/Rectifier (R/R) and the Stator.
The battery is there to power the electrical components of the bike when the engine is not running.
The job of the Stator is to convert mechanical energy from the engine back into electricity. The output from the stator on most modern bikes is three phase (hence the 3 wires) alternating current at a peak voltage well over the 12-14V DC voltage that your electrical system requres.
The R/R unit converts the alternating current (AC) in the diode bridge rectifier section then regulates the voltage to limit it to around 14V DC where it is fed back into the Battery and powers the rest of the bikes electrics.The voltage is higher than the battery voltage so current flows from the R/R unit back to the battery to charge it.
First off before you go running through the following tests, if you are having any electrical/charging problems then check that all electrical terminals/connectors are all tight, free from corrosion and secure. Also inspect for signs of either breaks or burning in the wiring or connectors.
To do a thorough test of the charging system or other electrical items you will require the use of a Multimeter and/or a 12v Test Light. A Multimeter if used correctly is going to give you more accurate results where as a test light will only give you an approximate result according to either the brightness of the bulb or if the bulb lights up or not.
1. IGNITION OFF
2. IGNITION ON, LIGHTS ON, BIKE NOT RUNNING
3. BIKE STARTED, LIGHTS ON, RUNNING AT FAST IDLE
4. FURTHER TESTS, IGNITION OFF
5. RESISTANCE TEST
6. VOLTAGE TEST
7. CURRENT DRAIN TEST
Be warned, don’t just go out and replace either one or the other without checking the other is functioning correctly first. Otherwise you could be just treating the symptom and not the cause and get caught in a cycle of either one or the other breaking your replacement. This could get expensive.
But hold on…. before rushing out and buying replacements the earth to ground should be checked and ruled out from causing any misleading readings.
There are three main sections to the charging system on most bikes (excluding the wiring inbetween). Those are the Battery, Regulator/Rectifier (R/R) and the Stator.
The battery is there to power the electrical components of the bike when the engine is not running.
The job of the Stator is to convert mechanical energy from the engine back into electricity. The output from the stator on most modern bikes is three phase (hence the 3 wires) alternating current at a peak voltage well over the 12-14V DC voltage that your electrical system requres.
The R/R unit converts the alternating current (AC) in the diode bridge rectifier section then regulates the voltage to limit it to around 14V DC where it is fed back into the Battery and powers the rest of the bikes electrics.The voltage is higher than the battery voltage so current flows from the R/R unit back to the battery to charge it.
First off before you go running through the following tests, if you are having any electrical/charging problems then check that all electrical terminals/connectors are all tight, free from corrosion and secure. Also inspect for signs of either breaks or burning in the wiring or connectors.
To do a thorough test of the charging system or other electrical items you will require the use of a Multimeter and/or a 12v Test Light. A Multimeter if used correctly is going to give you more accurate results where as a test light will only give you an approximate result according to either the brightness of the bulb or if the bulb lights up or not.
1. IGNITION OFF
2. IGNITION ON, LIGHTS ON, BIKE NOT RUNNING
3. BIKE STARTED, LIGHTS ON, RUNNING AT FAST IDLE
4. FURTHER TESTS, IGNITION OFF
5. RESISTANCE TEST
6. VOLTAGE TEST
7. CURRENT DRAIN TEST
Be warned, don’t just go out and replace either one or the other without checking the other is functioning correctly first. Otherwise you could be just treating the symptom and not the cause and get caught in a cycle of either one or the other breaking your replacement. This could get expensive.
But hold on…. before rushing out and buying replacements the earth to ground should be checked and ruled out from causing any misleading readings.
