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techtalk:evo:elec02 [2024/01/02 23:52] – hippysmacktechtalk:evo:elec02 [2025/06/24 09:36] (current) – [Relays] ixl2relax
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-| Note: Most people think of electricity in regards to voltage (as power), with power flowing from positive to negative to complete the circuit. For that reason, this explanation ignores the scientific facts of actual electron flow when conceptualizing the charging process, relationships and power distribution. This description includes the concept that power flows from the most positive source to the lesser positive connection (sometimes thru various devices) and eventually to the negative, ground, point. Voltages are typical with exact values varying under differing circumstances.\\ \\ The overview diagram is representative of a typical system and not exact for a specific Sportster model. Although later models have a more complicated distribution scheme, the charging components and operation are functionally the same for all models with alternators (Stator/Rotor). [[techtalk:evo:elec08|Some model wiring diagrams]] are in the Sportsterpedia. Refer to your FSM for detailed wiring diagrams, procedures & tests for your specific model. |+| Note: Most people think of electricity in regards to voltage (as power), with power flowing from positive to negative to complete the circuit. For that reason, this explanation ignores the scientific facts of actual electron flow when conceptualizing the charging process, relationships and power distribution. This description includes the concept that power flows from the most positive source to the lesser positive connection (sometimes thru various devices) and eventually to the negative, ground, point. Voltages are typical (such as 12v) with exact values varying under differing circumstances.\\ \\ The overview diagram is representative of a typical system and not exact for a specific Sportster model. Although later models have a more complicated distribution scheme, the charging components and operation are functionally the same for all models with alternators (Stator/Rotor). [[techtalk:evo:elec08|Some model wiring diagrams]] are in the Sportsterpedia. Refer to your FSM for detailed wiring diagrams, procedures & tests for your specific model. |
  
  
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 A fully charged, good battery, with no load, will show 12.7v - 13v DC when measured on a multimeter. Under light load the battery will read 12.5v and under heavy load (starting the engine) it will read 10.5v or more. The achieved voltage output of the Battery and/or Regulator, under load, will vary according to the existing charge level of the battery, load of the bike circuitry and the Stator output from engine RPMs. A fully charged, good battery, with no load, will show 12.7v - 13v DC when measured on a multimeter. Under light load the battery will read 12.5v and under heavy load (starting the engine) it will read 10.5v or more. The achieved voltage output of the Battery and/or Regulator, under load, will vary according to the existing charge level of the battery, load of the bike circuitry and the Stator output from engine RPMs.
  
-When the engine is running, the Rotor magnets rotate around the coils of the Stator, producing an alternating current (AC) output. This AC output is fed to the Voltage Regulator (VR) which converts the AC to Direct Current (DC) and limits (regulates) the voltage level of it's DC output.+When the engine is running, the Rotor magnets rotate around the coils of the Stator, producing an alternating current (AC) output. This AC output is fed to the Voltage Regulator (VR) which converts the AC to Direct Current (DC) and limits (regulates) the voltage level of it's DC output. Typical, regulated, charging voltage is 14.5v (+/-.2v) to the battery & system when the battery is fully charged.
  
 **Distribution** **Distribution**
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 Be sure that the battery wire is connected on one side of the Main CB while the VR & Keyswitch are connected on the other side. This arrangement prevents destructively high current flow (and potential fire) on the wiring in case the VR or Keyswitch develops an internal failure, like a short circuit to ground. Note that a few HD wiring diagrams incorrectly showed the VR connected to the battery side of the CB. If the bike you have is actualy wired that way from the factory, it should, for safety, be changed to the proper connection location.((HD mentions this in a Service Bulletin)) Be sure that the battery wire is connected on one side of the Main CB while the VR & Keyswitch are connected on the other side. This arrangement prevents destructively high current flow (and potential fire) on the wiring in case the VR or Keyswitch develops an internal failure, like a short circuit to ground. Note that a few HD wiring diagrams incorrectly showed the VR connected to the battery side of the CB. If the bike you have is actualy wired that way from the factory, it should, for safety, be changed to the proper connection location.((HD mentions this in a Service Bulletin))
  
-When the battery is fully charged, it may have a voltage higher than expected. After a one hour resting period is the time to test the voltage to determine the ability of the battery to hold a charge. __At that time it should still retain 12.7v - 13v DC for a full charge.__+After starting the bike, the charging system will take time to re-charge the battery. If you have had difficulty starting the bike or the battery has not been used or charged for quite some time, it may not be fully charged until the bike has been ridden several hours. 
 + 
 +When the battery is fully charged (externally or ridden), it may have a voltage higher than expected just afterward. It is important to rest the battery for one hour after the charging is complete. This one hour 'rest period' allows the battery voltage to stabilize in the battery cells. __After the one hour rest period, if the battery is capable of holding a full charge, measuring the battery voltage should still show it at 12.7v - 13v DC. This is a full charge condition.__
  
 \\ \\
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 (In the diagrams, S=Source & is B+ from the Battery or thru Keyswitch. L=Load & goes to the Starter Solenoid.)\\ (In the diagrams, S=Source & is B+ from the Battery or thru Keyswitch. L=Load & goes to the Starter Solenoid.)\\
 (Be sure to see the note at the end of this section regarding diodes in relays)\\ (Be sure to see the note at the end of this section regarding diodes in relays)\\
 +
 +For Starter Relay function [[techtalk:evo:engctl02#starter_solenoid_function|SEE HERE]]. For System Relay function see below.
 +
  
 **(1980-1992 & Early 1993)** **(1980-1992 & Early 1993)**
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   * **NOTE:** The 2007-2009 model years have a significant history of corrosion and gunk collecting in the fuse/relay tray causing low-grade shorts and erratic electrical operation - This is especially problematic if the bike is left outside or operated in the rain. It's a good idea to check & thoroughly clean this tray at least every year (or 4 to 6 months if parked outside).   * **NOTE:** The 2007-2009 model years have a significant history of corrosion and gunk collecting in the fuse/relay tray causing low-grade shorts and erratic electrical operation - This is especially problematic if the bike is left outside or operated in the rain. It's a good idea to check & thoroughly clean this tray at least every year (or 4 to 6 months if parked outside).
   * **NOTE2:** In the UK, check for part number Durite 0-727-13.   * **NOTE2:** In the UK, check for part number Durite 0-727-13.
 +
  
 **(2010-2013)** **(2010-2013)**
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     * Standard MC-RLY9     * Standard MC-RLY9
     * (Superceded from: 31579-04)     * (Superceded from: 31579-04)
 +
  
 **(2014-on)** **(2014-on)**
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 \\ \\
  
-**NOTE: Polarity & Diodes**+**NOTES:** 
 + 
 +**System Relay Function (2007-2013)** 
 + 
 +{{:techtalk:evo:elec:relay-systemcontrol.jpg?600|}} 
 + 
 +**Polarity & Diodes**
 <blockquote> <blockquote>
   *If the originally specified relay did not have a diode, the polarity of the connections to the relay coil made no difference - the relay functioned with either connection orientation. However, when a diode is present across the coil, for reverse EMF bleed off, it is important that the polarity of the normal connection provides reverse bias on the diode and not forward bias. The positive connection must be at the bar end of the diode (the silver band) which is opposite of the way diodes are used in many other applications.   *If the originally specified relay did not have a diode, the polarity of the connections to the relay coil made no difference - the relay functioned with either connection orientation. However, when a diode is present across the coil, for reverse EMF bleed off, it is important that the polarity of the normal connection provides reverse bias on the diode and not forward bias. The positive connection must be at the bar end of the diode (the silver band) which is opposite of the way diodes are used in many other applications.
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 </blockquote> </blockquote>
  
-(This document may be of interest: http://www.autoshop101.com/forms/hweb2.pdf)+(This document may be of interest: [[https://www.jdmfsm.info/Auto/--General--/Articles/Understanding%20Relays/hweb2.pdf|Understanding Relays]])
  
  

Trace: • EVO: Engine Control