Modern bikes are being released with all bells and whistles these days. ABS, Launch Control, Wheelie Control, Angle sensors etc etc…
Yet with all this technology, there still seems to be one electrical gremlin that crops up way too often on all but the newest of new bikes:The Regulator/Rectifier. Or Reg/Rec as it’s known. So, what does it do? The Reg/Rec is part of the bike’s charging system. It’s a dual purpose unit which both regulates and rectifies the voltage being returned from the bike’s alternator. The Rectifier takes voltage from the alternator (generally speaking in 3 phase format, although single phase is still commonly in use), in AC format and converts it into DC, the Regulator then takes this voltage (about 60-80v from a modern alternator) and limits it down to (typically) a maximum of 14.5v. This 14.5v DC current is then fed back into the battery to keep it charged, and keeps your bike running. As a result of these operations, the Reg/Rec goes through a series of very hold to cold cycles, couple in with this wet weather, seemingly poor mounting locations with insufficient cooling, and general wear and tear, and it soon becomes apparent that these items go through hell and back. So, what actually happens when this unit fails? That depends on what part of the unit itself fails.
Diodes: When a diode within fails, then it’s likely to fail to charge your battery at all, meaning that the battery will eventually run out of charge and the bike will either fail to start, or will cut out whilst running. Early indications of this usually include a weak headlight, and poor starting condition.
Shunt: When then shunt regulator fails you will see an overcharge condition on the battery, as it fails to regulate the current. A battery should receive no more than around 1.5 amps of current, but with failed shunt regulator can see 4-5 amps or current at varying voltage. This can have nasty side effects including (but not limited to), Headlight bulb blowing, Wiring loom melting, battery boiling. Early indications usually include brighter than normal headlight, headlight bulbs regularly blowing.
Total: When a total unit failure occurs then any of the symptoms above can occur, as well as seemingly random electrical faults cropping up.One thing to note, in most cases when a reg/rec dies, it will have caused some damage to the bike’s battery, so when replacing the Reg/Rec, it’s usually sensible to change the battery too!Not sure where to start? Want to learn more? Why not join one of our maintenance sessions to find out how to look after, and in some cases fix your bike? Contact Us or see our Facebook page to find out more!