Lights drain battery on sidecar outfit

[owain]

I've had this problem for a bit of a while and thought I'd share to see what a fix may be. I have 6v electrics on my bike with a DVR2 regulator and fitted with 6v incandescent bulbs. The sidecar light is also connected in parallel to the bikes lighting and also has a 6v bulb.

The issue is that when the headlamp is on, the battery gradually discharges. If I keep the revs high then I'll get bright lights but the engine tends to spend most of it time working at low to medium revs. I checked the battery with a voltmeter with lights off and the battery voltage does increase slightly from 6.2v to 6.4v at a mid rev range (I have no tacho, so not sure of the actual rpm). Although with the headlamp on the battery slowly discharges at a mid rev range.

The A10 is 1950 and as far as I know, the dynamo has never been refurbished. My initial thoughts were to buy a dynamo belt-drive kit as I've heard that they will increase the dynamos rpm....or do you think a dynamo reconditioning is the better option? Eventually I'd like to get both done but for the time being I can only afford the one. Opinions please?

[a101960]

First thought is to check the brushes for wear and clean any carbon build up on the commutator if the battery is OK. Also check earthing point. Is it clean and free from dirt and corrosion? Might be a good idea to fit LED lamps have a look at Paul Goff's site plenty to choose from there.

[Greybeard]

Check that the dynamo has a good connection to the engine/earth. Paint on the dynamo can insulate it.

[metalflake11]

First thought is to check the brushes for wear and clean any carbon build up on the commutator if the battery is OK. Also check earthing point. Is it clean and free from dirt and corrosion? Might be a good idea to fit LED lamps have a look at Paul Goff's site plenty to choose from there.

Yes, a good clean up might do the trick.

LED bulb is another option, I'm very pleased with the performance of the bulb I got from Classic Car LED's, (he sells them in singles) Very helpful, cheaper, superior quality control, and not brusque and patronising with his customers.

[Triton Thrasher]

You should be seeing 7 V with lights off.

Can the D and F leads joined together light a headlight bulb brightly?

[chaterlea25]

Owain,
What wattage bulbs are fitted?
If your wattage is exceeding or near the top end of the dynamo output the battery will discharge

John

[metalflake11]

Owain,
What wattage bulbs are fitted?
If your wattage is exceeding or near the top end of the dynamo output the battery will discharge

John

That's the first question that should have been asked really.

He could have a perfect charging system, but have a boy racer million watt headlight bulb fitted.

[Triton Thrasher]

Might the classic 6 V 30/24 W head bulb be in his future?

[morris]

As it happens, I tested the plunger’s electrics yesterday (6V with incandescent lamps all around).
I measured 8 amps on high beam with brake light on. A 6V system with a dynamo in decent order leaves you about 2-3 amps extra and therefore should be capable of feeding a couple of small wattage sidelights.
A set of new brushes and a commutator clean up is a good start. Check the bearings too. Particularly the small bearing, commutator side. And while you’re at it, disconnect the coil and measure it’s resistance. Should be about 2.8 ohms. After getting all that right, upgrading to a DVR belt is a good investment. That will squeeze an extra 10-15 watts out of the dynamo
If there is something really wrong with either coil or armature you wouldn’t almost have any output at all.

[owain]

Some sound advice there. I'll check the wattage of the bulbs this evening and take the dynamo out of the bike to test on a bench. The dynamo isn't painted so I don't expect a poor earth to be the problem, although I'll give it a good clean none the less.

[owain]

Righto, I checked out the bulbs;
Headlight: 6v 35/35w
Sidecar: 6v 4w
Taillight: Lucas 334 bulb (24v  24/6w??)

So I think it's safe to say that the tail light is the problem. That being said, I decided it'd be a good idea to give the dynamo an inspection and a decent clean. The armature and field coil were covered with a decent layer of grime and I also noticed abit of damage to the brass near the top of the armature (i.e. just before the part where the brushes touch).

Anyway, my thoughts are either A) Just replace the bearings and shove it all back together after a thorough clean or B) Replace the armature (and field coil) whilst I'm at it. Thoughts?

[RDfella]

I'd check the segments of the armature and the field coil for resistance and if OK re-use. The 'pound in your pocket' is better there than in someone else's.

[chaterlea25]

Hi Owain,
A normal tail light bulb would be 6v / 5/21watt
The tail light element should be the 6w and the brake light the 24w so you can usually leave the brake light out of the calculation
I think LED bulbs would help a lot
If the dynamo, regulator and battery are good and the voltage rises to 7.2 volts with lights off all should be good
6 volt systems need careful attention to connections, switch contacts and wiring to give their best

A failing battery where the voltage will not rise to the cut off point of the regulator (7.2v) will rob the energy from the dynamo in a bid to raise the voltage to 7.2v

John

[morris]

Righto, I checked out the bulbs;
Headlight: 6v 35/35w
Sidecar: 6v 4w
Taillight: Lucas 334 bulb (24v  24/6w??)

So I think it's safe to say that the tail light is the problem. That being said, I decided it'd be a good idea to give the dynamo an inspection and a decent clean. The armature and field coil were covered with a decent layer of grime and I also noticed abit of damage to the brass near the top of the armature (i.e. just before the part where the brushes touch).

Anyway, my thoughts are either A) Just replace the bearings and shove it all back together after a thorough clean or B) Replace the armature (and field coil) whilst I'm at it. Thoughts?

Are you sure that the tail light bulb is 24V? That would be one for a lorry then...
Anyway, the 6W would be for the tail light and the 24W would be for the stop light. I don’t suppose that you ride with your foot on the brake and have your stop light on all the time... 
Your constant consumption with lights on would be around 45 watts then, which the dynamo should deliver easily (normally minimum 60 watts, and with a belt drive may go up to 80 watts)
If the field coil measures around 2.8 ohms, I would just change bearings and brushes, clean out the grooves between the commutator segments and give it a test run. When cleaning the grooves make sure you make a straight cut. A ground down hacksaw blade is a good tool for this purpose.
On the bench, driven by a drill, you should measure an output of at least 14-18V depending on the speed of your drill

[Swarfcut]

 Owain.  With care and taking a light cut with a sharp tool, the commutator segments can be machined back to produce an as new running surface for the brushes, and the insulation between the segments then cut back as already pictured.  Depends on the existing thickness of the segments, and the depth of the wear.

 If you do go down the new armature road, the cost of 6 Volt and 12 Volt components are not too far apart, and it is worth going for  a 12 Volt system with a higher output.

   Like RD recommends, I'd try checking the armature and field coil against electrical spec. and if satisfactory, cleaning up the segments.  Stick with what you've got for now, meanwhile researching options for a possible upgrade. The cost of those pounds will certainly clear the mind as to the way you go.

 Swarfy