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Still got a charging problem

Hi everyone

I have recently rebuilt my dynamo. It motors well and will light a build when i bridge the two connections etc. I have a drv2 neg earth and when i test the regulated output with a multimeter i get 6.7v.

I have tested the voltage across the ammeter with lights off etc not running and get 6.2v, running i get 6.5v.

When i turn on lights the ammeter needle goes -3 amps but when i run the bike it doesnt change, just stays at -3A.

Can anyone suggest why that would be the case please.

Many thanks

Ant

Re: Still got a charging problem

Have you flashed it?
Look here if you don’t know how
https://www.matchlessclueless.com/electrical/lucas/repolarising-lucas-dynamo/

Re: Still got a charging problem

Something else to check if re-polarizing the dynamo does not work is the clutch mechanism in the magdyno drive. If this is slipping the generator will not charge properly.

email (option): msawicki@fsu.edu

Re: Still got a charging problem

Have you checked the wiring? It may have been miswired to only register discharge, rather than the sum of charge and discharge. Check the connections on the back of the light switch.
IMG-7968

email (option): John.childs1@btopenworld.com

Re: Still got a charging problem

All

Thanks for the comments, i will work through those suggestions - thanks !

Re: Still got a charging problem

So I had a quick look at lunch (only advantage of current world covid situation / working from home !) and i got the output figures from the DVR2 wrong - sorry (didnt disconnect the battery). It actually fluctuating all over the place. I checked continuity on the the regulator earth and its fine and output from the dynamo is fine so i must of blown the reg some how.

What are the current alternatives to DVR2 ? i thought they were protected against reverse polarity etc (my wiring is correct from the reg to dynamo) Does it pay to avoid cheap and cheerful ?

Thanks

Ant

Re: Still got a charging problem

Ant,
I use a Lucas RB108 electro-mechanical type. Successor to the original MCR1 and 2, looks near enough to a first glance when painted. Widely used on classic cars, bikes and tractors so still easily available at reasonable prices.

email (option): John.childs1@btopenworld.com

Re: Still got a charging problem

Ant, IT is better to use a multimeter instead of a bulb when you bridge the two wires. Then you can see the voltage increasing of not.

John

email (option): john.kater@chello.nl

Re: Still got a charging problem

Electronic regulators have varying degrees of protection against short circuits...None of them are protected again connection to an incorrectly polarised dynamo which will immediately destroy them......

The golden rule with electronic units is to connect them to the system LAST, after you have tested everything else...So, rewire the bike if required, fit a charged battery and test for possible short circuits, correct ammeter connections and correct system function.. Then test the dynamo output and polarity and when you are sure all of that is functioning as intended connect the regulator...

If you have a varying output, particularly at a fairly constant throttle setting, there may be a problem with the magdynamo clutch...Ian

email (option): ian@wright52.plus.com

Re: Still got a charging problem

Thanks for the advice and support gents - appreciate it

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