FAQ for the V-Reg Dynamo regulator

HOMEDynamo Regulator Index

V-Reg IIIf after fitting the V-Reg you have a problem, following these notes should have the unit working. The V-Reg has been designed thoroughly and is very tough so most problems will be with the dynamo or wiring. First make sure you have done Polarising and Testing as detailed in the Fitting Instructions, as in a lot of cases this will clear the fault.

No Charge: My dynamo/regulator doesn't charge the battery?
Despite the ammeter not deflecting to the charge side it may actually be charging. First check for a charge voltage at the battery as per the Fitting Instructions for the V-Reg. If this voltage is correct then it is most likely that the Ammeter has been miss wired. There are basically 3 circuits at the Ammeter:
  1. The Charge - from the Regulator (A wire).
  2. Discharge - lights (sometimes ignition).
  3. Battery. The wire to the battery must always be on its own. If the charge from V-Reg "A" terminal is connected straight to the Battery connection, you will be seeing  the discharge but NOT the charge.
The dynamo might be reverse polarised --- Repolarise.
The battery might be flat --- the V-Reg must be used with a well charged battery (unlike the original electro/mechanical regulators).
D and F reversal within the dynamo. --- this fault can cause many effects, no charge, over charging or even damage to the regulator.

 It is a new battery!
This does NOT mean that it is fully charged. A 'New' battery can be flat very quickly if left discharging (lights on or wrong connections). There have been cases of faulty from 'new', eg filled with water only.

  I have just charged the battery.
Often there is a reliance on the trickle charge 'Optimate' type of charger to properly charge the battery. A; If the battery was really flat it might take several days to fully recharge, B; A well flat battery often will not charge properly at all from such a charger. Please use a normal charger that says it is giving a couple of amps and charge for a few hours at least.

Blown Fuse: When connecting the battery the fuse blows or there is a buzzing from the dynamo or there is a small spark and/or the battery goes flat in a few hours.
All of these 'faults' can be caused by a reversed battery or Regulator ie you have a regulator of the wrong polarity that you are trying to use. Also it is not unknown for a battery to be reverse charged! Hence every thing looks correct but it is NOT. Check battery polarity with a multimeter.

 At tickover the bike shows a small discharge,
This is correct, the V-Reg gets its Field current from the battery, which then shows on the Ammeter.

 The Ammeter shows overcharging!
A prime reason for this is that the dynamo has an internal short between D and F. (or a similar wiring fault on the bike) such that the regulator is in effect out of circuit, not regulating. Once this fault is fixed, the Regulator should function correctly.

 Testing the Regulator.
No meaningful tests can be done with a multimeter on ohms. If after having checked all of these points you still have a problem then we are happy to test the V-Reg. After returning it with return postage.

 What factors affects the polarity I use?
There is no strict rule nor technical reason, except that the electronic regulator IS polarity conscious, therefore once you have chosen a specific polarity regulator you are committed.
Some points to bear in mind if you are undecided:
Digital Multimeter: These can have an unsettled display, due to being by affected by ignition interference. Try another meter preferable an analogue (pointer type).

HOMEDynamo Regulator Index

23 October, 2009