Welcome to our FAQ page. You will find the answers to many queries on the individual product pages or in the datasheets which may be viewed on-line or downloaded. Otherwise we hope you will find the answer you're looking for here.
Yes, it also works fine with the lower power E3H and E3HM versions.
Yes, in both cases.
Yes, as long as field is wired to earth and original cut-out removed.
After a simple modification from 3 brush to 2.
Maximum output is not really limited by the regulator. 75W for 6V system and 100W for 12V system is safe for the regulator.
Nominally 7.2 V in a six volt set-up and 14.2 V for twelve volts. More is definitely not better here. For example 14.5 V as commonly stated as 'correct' will mean higher trickle charge leading to more topping up and shorter life for your battery.
Your battery's NEGATIVE terminal should be connected to the chassis or frame.
Disconnect the D & F wires from the dynamo. Take a wire from the unearthed (POSITIVE) terminal on the battery and 'flash' it onto the F terminal of the dynamo. That is touch the 'live' wire onto the F terminal briefly, for a second will do it. A small blue spark should be seen. Your dynamo is now polarised NEGATIVE earth, simple as that.
(Swap POSITIVE and NEGATIVE in the above to polarise for POSITIVE earth)
This procedure may be used to 'wake up' an old dynamo which has not been used for a long period or to confirm polarity in case of any doubt, as well as to deliberately reverse the polarity.
It is a good idea to stick a prominent reminder near to the battery when the vehicle's earth polarity has been swapped, to avoid future polarity sensitive connection problems.
Shunt Field Dynamo e.g. Lucas: Remove any wires from the Output and Field terminals (Lucas D and F) and connect a wire between them. Connect a 12 V bulb (e.g. 21 W indicator bulb) between the two linked terminals and 'ground' or the dynamo case. Spin up the dynamo and at modest revs the lamp should glow brightly, even with a 6V unit. Increase the speed slowly and do not continue this test for long. Even better use a voltmeter to monitor the voltage (the field coil acts as a load). The meter will also show the polarity of the output. 6V or 12V should be seen on the meter at a speed equivalent to perhaps 30 mph on the road.
For a Series Field dynamo e.g. Bosch or a Dynastarter: Instead of the linking Output (61/D+) and Field (DF), link Field to ground. Connect the bulb or meter between Output and ground.
Many 6 Volt dynamos on both motorcycles and cars work perfectly well at 12 V with no changes. The benefits of going to 12 V include better lighting and easy parts availability. The downside is that charge balance will take place at typically 30 % higher speed; no problem for cruising but could be around town. More power will be available at 12 V as a result of lower heating in the armature (half the current for given power). The DVR2 allows swapping to 12 V and back to 6 V by a very simple wiring change.
6 V dynamos may be rewound for 12 V with more turns of thinner wire to provide higher voltage. The benefit is a lower cut-in speed but this will be offset by lower power output than a 6 V machine run at 12 V (at least 50% more power available). Reliability may suffer and the initial cut-in may be delayed where the residual magnetism is low. The DVR2 gives much more output at lower speeds than some (puzzlingly) popular regulator units in any event; one will actually discharge the battery at low speed. So worth trying the lower cost & hassle DVR2 upgrade first.
No, not really helpful. Unless you have say a 12V 60W headlight on and often sit in a lot of slow traffic. A discharged large capacity battery loads the dynamo more and for longer. If a large battery is fitted as in the case with an retrofitted electric start a current limited regulator may better protect the dynamo and prevent nuisance fuse blowing, if the battery becomes discharged.
Spend your cash on an ammeter that works well instead. They do not all flicker wildly all the time if the charge regulation is good. A voltmeter will sometimes show a misleading high reading despite the battery being shot. Ammeter current gives a clear indication of the charge at a given time and is a better option in a dynamo system.
Yes, the DVR2 will start with a very low battery. If fully discharged it will wake up with battery disconnected (magneto ignition assumed!), then reconnect the battery. Regulation will not be as good as in normal use, but a useful get you home measure after dark.
A matter of taste and depth of pockets perhaps. But the Lucas dynamo (for example) in reality is a rugged & reliable unit, and requires minimal maintenance. Coupled with a DRL electronic regulator adequate charging is possible at all times for normal electrical loads.
Certain modern motorcycle a.c. generating replacements have a history of reliability issues, can be noisy, and cruising speed output may be little if any better than with the original d.c. generator.
In addition click Lucas dynamos and charging system (Matchless-clueless) for an excellent practical guide for fettling your electrics. Written with bikes in mind but much is relevant to cars and other dynamo systems as well. (Why reinvent the wheel?)
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