Looking for help charging system not charging battery on 1999 Harley Davidson fatboy
Check regulator ground by using an ohmmeter with one lead on a known good ground, such as the battery ground cable, and the other on the regulator base.
The connection where the alternator stator wires plug into the regulator could be corroded/dirty and need to be cleaned and sprayed with electrical contact cleaner and protected with dielectric grease because corroded wires going to the battery or alternator from the stator or the regulator will affect the ability of the charging system to properly charge a battery.
Motorcycle voltage regulator connections must be clean and tight for proper operation so it must be verified that both the AC (stator) connections and the DC (battery supply side) connectors are clean, fully inserted and locked in place with the regulator latches (they should also be coated with dielectric grease to keep them clean and corrosion free).
The motorcycle voltage regulator is a series regulator that is also a rectifier that changes stator supplied alternating current (AC) to direct current (DC) which the battery system requires. If the charging system does not keep the battery properly charged both with regards to Voltage (between 13 VDC minimum and 15.5 VDC maximum) and the current supply at a high enough amperage to meet the system lighting, ignition, TSM/TSSM, security and accessory requirements plus a minimum of 3.5 more amps (3.5 amps more than the foregoing system requirements) there are a number of tests that can be done to ascertain why.
As the voltage regulator must have a good, clean, tight (and otherwise secure) ground connection for proper operation a Voltage Regulator Ground Circuit Test can be accomplished by connecting an ohmmeter to a known good ground (like the battery negative post) and the case of the regulator. If there is continuity with little resistance the ground is GOOD and nothing more needs to be done BUT if there is NO continuity or there is more than minimal resistance the ground will need to be fixed so there is a low resistance continuity by either locating and fixing the poor ground or adding a new grounding wire from the regulator case to a know good ground.
A Voltage Regulator Power Circuit Test can be accomplished by turning OFF the Ignition, disconnecting the voltage regulator and with an ohmmeter set to the Rx1 setting, testing for continuity between the voltage regulator wire harness supply terminal and the main fuse terminal (with the fuse removed) and if there is continuity present then the wiring circuit here is GOOD but if there is NO continuity then you will need to either find the open and repair it or replace the whole wire running from the voltage regulator to the main fuse.
As there should be no short circuit in the power supply from the regulator to battery (main fuse) wiring OR in the regulator internal circuitry continuity from these both need to be checked again with an ohmmeter set to the Rx1 setting. If the regulator to main fuse wiring connector is not disconnected from the regulator you can connect an ohmmeter with one lead on the regulator supply wire terminal end at the main fuse (with the main fuse removed) and the other lead to a known good ground. If there is NO continuity then you know that both the supply wire and the regulator are okay (as there is no short to ground). BUT if there is continuity then either the regulator or wiring or both is/are shorted to ground. To determine where there is a short circuit (i.e. either the wiring or the regulator internal circuitry) you must disconnect the DC side of the wiring harness (the connector at the DC side of the regulator) from the regulator and test between either or both ends of the wire i.e. from the regulator wire harness.
AC Output Check
Disconnect the voltage regulator connector from the alternator stator wiring and then connect an AC voltmeter across both stator sockets of a two wire stator, or if a three wire stator across two of the three for example 1 & 3 and then later you will repeat the test between 2 & 3 and later between 1 & 2. THEN run the engine at as close as possible in the circumstances to 2000 RPM. The AC output should be approximately 32-40 VAC, approximately 16-20VAC per 1000 RPM. If you have done a stator static test and the stator has proven to be in good mechanical condition and the AC output is below specifications, the charging problem is going to be a faulty rotor. If you have not done a static stator check yet and the AC output is less than as set out above it may be that the stator is defective and the static stator check will need to be done. While the regulator has nothing whatsoever to do with the alternator output, if the alternator output is good the regulator might be defective in either rectification or in limiting the output to the battery to under 15 VDC. If AC output is low and the stator has passed the static stator check then it is likely that the permanent magnets in the alternator rotor are weak. A permanent magnet can lose its magnetic strength if it is dropped or shocked such as letting it snap into place when being installed or possibly by use of an impact wrench to remove the compensator fastener etc.
May 27, 2014 |
Harley Davidson FLSTF - FLSTFI Fat Boy...