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Purpose of charging system

To provide the bike with electrical energy at all all times


The system has 6 main functional components, viz.

  • Engine: provides mechanical energy
  • Alternator or generator: converts mechanical energy from the engine into electrical energy in the form of Alternating current (AC)
  • Rectifier (external link): converts the AC (external link) energy into direct current (DC) (external link) energy.
  • Regulator: limits the battery charge to a safe maximum
  • Battery: chemically stores electrical energy for use when the alternator is unable to supply sufficient, e.g. starting.
  • Load: the rest of the bike electrical equipment, ie loom, connectors, lights, ignition, starter etc.

Note: the rectifier and regulator are physically contained in the same module, the 'RR'


This is a probable representation of the XL1000v charging circuit deduced from various sources. The 5 way connector is on the Reg/rec, the 4 way connector the main battery connection and the 3 way connector is in the lead from the alternator to the reg/rec.

Charging circuit fault symptoms

  1. main 30A fuse blows with the ignition off.
  2. main 30A fuse blows ONLY with the ignition on.
  3. starter wont turn engine. Instruments, e.g. clock reset whilst trying.
  4. when starting instruments reset.
  5. engine stops and wont start.
  6. battery goes flat when on the bike with ignition off.
  7. battery goes flat on the bike ONLY with the ignition on.
  8. off the bike the battery either does not bench charge or goes flat quickly from a full charge .
  9. smoke issues from around seat or around steering head or elsewhere, followed by other electrical failures

Action on symptoms

  1. probably a short circuit in the RR. Unplug connector from RR (behing RHS grey side panel) and try again. Use a
  2. hi-wattage bulb instead of a fuse to test for short circuit, its cheaper. The bulb will light if there is a -
  3. short circuit.
  4. probably a fault in the load, i.e. a short circuit in the wiring or connectors or other component not in the charging system, e.g. ECU
  5. flat battery because
    • battery not charging due to faulty RR, Alternator, or load or flat battery due to not using the bike for too long without charging the battery: Charge battery, start bike and check charging voltage with engine running.
    • faulty battery, check by charging off bike. If it charges OK and retains its charge overnight its probably OK
  6. see 3
  7. possibly flat battery, measure voltage. If low see 3.
  8. probably bike draining battery through charging circuit. Unplug RR and test for fault.
  9. probably low or no charging current. Check charging voltage with engine running
  10. faulty battery, replace
  11. could be
    • RR burning out. Stop immediately and check
    • could be alternator burning out. Stop immediately and check

Cautionary note

Faults in load, battery, rectifier, regulator, alternator and associated wiring tend to cause or are caused by failures of the other components. Therefore when a fault condition arises in any of them it is prudent to check all the components before replacing a known faulty one. See the links at the bottom of this page for handy fault finding procedures

Fault modes for various components

Note: some of these occurrences are alarming and expensive to put right, but the most likely failure is a faulty RR blowing the main fuse with nothing else involved.

  • Engine: well, if the engine stops the battery wont charge
    • Loose rotor, if the rotor key shears on the crankshaft the rotor will not be driven by the engine, resulting in lack of charge. The most likely noticeable symptom however will be the noise of the loose rotor eating the stator and possibly the crankshaft. No reported occurrences as far as I know but I've had it happen on another bike.
  • Alternator (or wiring and connectors to)
    • short circuit coil, will possibly heat up burn out and go open circuit resulting in low charge
    • coil shorted to frame, will result in low charge
    • open circuit coil, will result in low charge.
    • two or more coils open circuit, no charging at all.

very hot stators can result in generation of smoke which will rise in unexpected places. Sparking open circuit stators can ignite oil mist in the crankcase causing noises and smoke.

  • Rectifier (or wiring and connectors to)
    • diode(s) short circuit, will discharge the battery into the alternator; should blow main fuse. If fuse doesn't blow it will possibly damage the alternator and probably flatten the battery irretrievably. Will possibly get the RR hot enough to smoke and if your unlucky the same with the alternator.
    • diode(s) open circuit, will reduce charging ability. May not show up until a heavy load has drained the battery over time, eg long trip with lights, grips etc on as there may be sufficient charge to maintain the battery on low loads.
  • Regulator (or wiring and connectors to)
    • SCR(s) open circuit or not triggering will result in overcharging the battery, indicated by over voltage, then ruined battery. Possible danger to load of too high a voltage on electronics and bulbs etc.
    • SCR(s) short circuit , insufficient charge leading to flat battery. May not show up until a heavy load has drained the battery over time, eg long trip with lights, grips etc on as there may be sufficient charge to maintain the battery on low loads.
  • Main Fuse and fuse holder,
    • blown fuse, there will be no charge, the battery is now safe but the RR and alternator not quite so safe. Fuses can be intermittently open or even high resistance.
    • fuse holder high resistance due to dirty contacts, will cause low voltage to bike electrics including starter solenoid but not the starter motor, therefore the engine may turn over briskly but fail to start.
  • Battery (or wiring and connectors to)
    • cell(s) having high resistance will cause the battery to have a reduced charge or inability to hold charge for any time. Voltage readings will be normal, so the battery appears to the charging circuit as a fully charged battery
    • cells(s) short circuit, battery will not take a charge and voltage readings when not running will be low. Charging system will put a lot of energy into the battery as it appears as constantly flat. Battery will possibly boil, may blow fuse. note: I'm unaware whether the RR has any over current protection. probably not as a higher than normal current should blow the fuse. 30A into the battery though would result in some worrying consequences.
    • High resistance battery terminal connection; may also effect charge but main symptom will occur under heavy discharge, particularly starting when the heavy current drawn by the battery will cause a voltage reduction to the bike supply resulting in sluggish or no rotation of the starter motor, possible resetting of electronics,eg clock, and possible smoking at terminals.
  • Load, this includes everything up stream of the main fuse, loom, lights,fan,ignition etc.
    • very low resistance or short circuit in load, this should blow the main fuse and not harm the charging components
    • open circuits in the load will not effect the charging components or the charging action.

Low charge rate may not show up until a heavy load has drained the battery over time, eg long trip with lights, grips etc on as there may be sufficient charge to maintain the battery on low loads.

  • Perfect fault (of charging system)
    • rectifier diodes go short circuit and fault current is below fuse rupture value ~30A

battery discharges through RR , burns out alternator and irredeemably flattens battery.

  • This can happen with the bike unattended at any time.

Testing the RR

To test the thyristors and the regulator circuitry you need an external power source. The most suitable is a variable DC power supply adjustable between 0 and 20 volts. The regulator works by shorting out the coils of the alternator so a 12 volt 1.7W bulb is placed in circuit to limit the current taken from the power supply, thus the current is limited to a harmless 100 to 150 mA. Even if an accidental wrong connection is made damage to components with this low current is unlikely. The bulb also gives a visual indication of the operation of the controller. The power supply is slowly turned up from 0 volts. The bulb remains off until the regulator reaches its cut-off voltage. At the cut-off voltage the bulb lights. The power supply voltage must then be completely turned down again to 0 V, since the thyristor (SCR) (external link) remains on down to a voltage of 0.7 volts (the bulb will slowly darken). The output voltage you can check directly with a multimeter between positive RR output and RR ground connection.

Giving the components an easier time

  • Ride with the headlights (or heated jacket etc) on. Due to the way the regulator works using near the maximum output of the alternator probably makes the RR run cooler and therefore last longer.
  • make sure the back of the RR has a good thermal connection to the frame by cleaning the contact surfaces and applying heat sink compound or thermal pad, eg (external link).
  • clean the battery terminals and refix leads using Vaseline or silicon grease on bare metal
  • Because batteries self discharge over time, and even quicker if connected to a bike alarm, maintain the battery charge with a bench charger when not in use for more than a couple of weeks, one capable of maintaining a low trickle charge.


Created by jp on the UK Varadero forum - copied to this Wiki by SB on 23/05/17.

electrical/battery_and_charging.txt · Last modified: 2017/05/23 06:42 by sb66