charging part 2

mossop · Post by **mossop** » Fri Jun 17, 2011 7:01 pm

Hi all

after my last correspondence on charging, everthing was going well with the charging of the battery whilst riding in the dark, until wednesday night coming home from the south lincs and peterborough VMCC evening and guess what, no charge at all (total discharge on ammeter)but did have lights and got home

I have checked the CVC unit and the cut out is not closing at high revs, in fact its not doing anything. I have read that these units should not be tampered with (and my local lucas service depot is now a car park) so i assume it cannot be checked anymore and a new one needs to be ordered. is this my next option ?.

SPRIDDLER · Post by **SPRIDDLER** » Fri Jun 17, 2011 7:25 pm

Peter
It may not be a faulty CVC - it may be that the battery was sufficient to keep the lights going though.
The CVC may appear 'dead' because there's no output fom the dynamo to stimulate it or there's a boken wire between dynamo and CVC.
I'd check for dynamo output first.
These mechanical CVC's are very basic and usually repairable but need some skill and a suitable test rig to adjust them / set them up.
I can give you contact details for a shed dwelling Sparks (retired technician) who can usually supply either an exchange unit or repair yours.Edited by - SPRIDDLER on 17 Jun 2011 6:26:18 PM

mossop · Post by **mossop** » Fri Jun 17, 2011 7:30 pm

no i dont think so. The ammeter needle always stayed in the middle when the lights were on, but this time when the lights were on it went all the way to the left and showed a full discharge and wont move if you rev the engine and the lights dont grow brighter either. also when I was checking the CVC unit a few weeks ago, it open and closed freely when the engine was revving but this time it does nothing which makes me believe that it could be knackered.

Don Madden · Post by **Don Madden** » Fri Jun 17, 2011 8:55 pm

In 50+yrs of riding British Iron I have had little trouble with the CVC, needing only occasional cleaning of contacts & voltage adjustment. I have had dozens of the dynos fail, possibly because I have the sportier bikes that rev higher. I go with SPRIDDLER.

If you must ride after dark, fit an Alton unit. Cheers, Don.

aobp11 · Post by **aobp11** » Fri Jun 17, 2011 9:08 pm

That's a far too quick conclusion Peter, see Spriddler's remarks. First of all check the dynamo output.
Albert

zwarts · Post by **zwarts** » Sat Jun 18, 2011 5:18 pm

Don't jump to the conclusion that the AVC is at fault without checking the dynamo output and wiring first. Also ,don't assume that the answer is to fit an electronic control unit. As others have pointed out, these electro-mechanical CVC's are a very simple reliable unit and a lot more 'user friendly' than a sealed electronic device of the 'throw away when faulty' type. I have seen very few of these Lucas CVC's which are beyond repair, with a bit of understanding and logical fault finding, but have never seen a repairable electronic regulator!
Bob.

wilko · Post by **wilko** » Sun Jun 19, 2011 4:55 am

In 6,000 miles i've never touched mine. Check the dynamo output with the reg disconnected. Make sure a wire hasn't vibrated off your headlight switch.

mossop · Post by **mossop** » Mon Jun 20, 2011 10:47 am

Hi All thanks for your comments

I will check the dynamo out put when I get back from my holiday in a few weeks time and up date the forum then. I did check the wiring yesterday from the dynamo right through to the headlamp and it all looks to be ok with good bullet connections but thats not to say that it could be broken in the loom so if I wanted to replace any of the wiring, what ampage/watt wire would I need ? as i can't find this info in any of the books I have.

SPRIDDLER · Post by **SPRIDDLER** » Mon Jun 20, 2011 12:37 pm

First check must be for output from the dynamo: Remove both of the D and F wires from dynamo at the end plate. Use a separate piece of wire to bridge D and F sockets at the dynamo end plate. Take a wire from this bridging piece and connect to a center pip of a 21 (brake light) or 35 watt (headlamp) bulb. Earth the metal case of the bulb. Run engine at just over tickover speed. Bulb should brighten as revs increase. Do not over-rev as this output is unregulated and voltage will rise rapidly with revs until it blows the bulb. It's better to test with a load (at least a 20 watt bulb) rather than a voltmeter since although a meter will measure voltage it will not show the wattage (power) being produced without a load being applied. Your max dynamo output is 42watts.
As you probably know you can check the continuity of each loom wire using a meter or a test lead with a bulb. More reliable than visual checks, especially when wiring disappears under petrol tank etc.
You need to give the main feed wire at the headlamp switch a tug, not just look at it. It's cramped in there and just because the wire is in place is doesn't guarantee it's connected. (Personal frustration at 3 a.m. at a French roadside )
You're on 6 volts so I'd use minimum 14/0.3 (14 strands of 0.3 diameter. Approx 15 amp). Larger dia is better than smaller. Make sure your fuse(s) is rated lower than the wire!!
Have a look in Halfrauds or take ITMA's tip and get a loom (which will have a selection of colours) from a breaker - making sure that the wire selected is of sufficient dia.
IF there's no output from the dynamo check that the brushes are not stuck in their holders and that the commutator is clean.
FWIW and as a matter of interest a dynamo specialist once told me that the commutator stays cleaner if run under load - i.e with lights on. Perhaps an urban myth but no harm in trying.

Lucas dynamo service info:
http://archives.jampot.dk/Technical/Ele ... LM_E3N.pdf

mossop · Post by **mossop** » Mon Jun 20, 2011 1:14 pm

Hi Neville

Thanks for all the info. Theres lots for me to look at when I get back from my hols.