Motorcycle Dynamo Voltage Regulators

High Performance with Rugged Reliability

Why another solid state regulator?

"A couple of years back I converted to a 12 Volt electrical system on my 1960 BSA A10, employing a commonly available electronic regulator. At the same time I fitted electronic ignition to replace a worn out auto advance unit and tired magneto. With the updated ignition now dependant upon battery charge the efficiency of its charging system became critical. The regulator I had chosen struggled from the start to maintain a decent charge rate. At one stage I ended up with a flat battery during daytime riding. No lights, just the ignition drain of about 2 Amps (plus the low speed redundant 2A field current) was a problem following much local bimbling around. Fitting a belt drive kit to increase the dynamo speed by 20% helped. But as an electronics designer I realised that a better regulator solution should be possible........

After some serious development effort the first DVR was produced and proved very effective on the A10, and then on a number of other machines. Charge balancing speed was 10 to 20% lower, and regulation across the rev. range improved at the ammeter. A refined unit has been subsequently designed which uses highly reliable Surface Mount components, and with added protection for mis-connections and overload. This is the version now available as the DVR2"

(Mike is currently Secretary of the Hampshire branch of the BSA Owners' Club.)

Some Questions we have been asked, and the Answers.

Question: "Does the DVR2 suit Lucas E3L and E3LM dynamos ?"
Answer: Yes, it also works fine with the lower power E3H and E3HM versions.

Question: "Will your DVR2 suit:
             a. The Lucas MC45L dynamo fitted to my Sunbeam / Scott,
             b. A Lucas C35SD dynamo on my Ariel Square Four ?"
Answer: Yes, in both cases.

Question: "Is the DVR2 suited to the Miller dynamo fitted to my Vincent / Velocette (etcetera) ?"
Answer: Yes, as long as field is wired to earth and original cut-out removed.

Question: "Will the DVR2 suit the dynamo fitted to my MZ ?"
Answer: Yes, as long as field is wired to earth and resistor (where fitted) removed. Similar for Jawa / CZ.

Question: "What is the maximum power output of the DVR2 ?"
Answer: Maximum output is not really limited by the regulator. 75W for 6V system and 100W for 12V system is safe for the regulator.

Question: "Will I benefit from fitting a larger capacity battery ?"
Answer: No, not really helpful. Unless you use 12V 60W headlight in a lot of slow traffic. A discharged large capacity battery, loads the dynamo more for longer.

Question: "Will I benefit from fitting a voltmeter or voltage monitoring device ?"
Answer: Spend your cash on an ammeter that works well instead. They do not all flicker wildly all the time. A voltmeter can show a good reading for a shot battery. Monitoring charging current is the better in a dynamo system.

Question: "What voltage can I expect at the battery using the DVR2 ?"
Answer: Nominally 7.2 V in a six volt set-up and 14.1 V for twelve volts. More is definitely not better here. For example 14.5 V as commonly stated as 'correct' will mean more topping up and shorter life for your battery.

Question: "Will the dynamo start up with a completely flat battery ?"
Answer: No, but the DVR2 will start with a very low battery. If fully discharged it will wake up with battery disconnected (magneto ignition assumed!). Regulation will not be as good as in normal use, but a useful get you home measure after dark.

Question: "Wouldn't I be better off installing a nice (expensive) modern alternator alternative ?"
Answer: A matter of taste perhaps. But unarguably the Lucas dynamo (for example) can be a very reliable unit, requiring only minimal maintenance. It is evident that modern generating replacements have significant reliability issues, and that low speed output may not be that much better than with the old technology.

Please send any questions to dvr@manortec.co.uk or call 01489 880552.

DVR description
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