SQ4 charging system

[greg.geonetta]

Hello all

Was wondering if any of you folks have tried adjusting the mechanical regulator to get a little more juice to the battery?

I have , and it has made quite a difference. I'm now getting about 7.1 volts at about 2000 rpm, after which the regulator cuts back a bit.
I believe this is about right, I know a normal 12v system will deliver in the neighborhood of 13.5-14 volts to the battery at full output.

I had to fine tune it, you don't want too much as it will fry the battery. I used a digital voltmeter to get an accurate reading of exactly how much voltage the battery is getting.

Take the cover off the regulator, it is the adjusting screw on the right on the back of the regulator. It doesnt take much, maybe 1/8 turn.(clockwise)

[bill.bottrill]

Interesting Greg,
I was tempted to poke around in that little black box but thought better of it.I wonder if anyone can supply the setting up details for the 6 volt regulator box They must all be the same on any early british bike.Is there anything in the technical section.( I've tried to get into it even asked admin but no joy.)
The boxes must have been set up before they left lucas,so that's why I didn't mess with it on the bike.
I have a different problem,the other relay the cutout one ,It works O.K. but when I use the main headlight and come down to tickover the ammeter smacks across negative(someone has adjusted the points, and the relay doesn't drop out quickly enough, now I can just readjust using a digital voltmeter but would really like to set it properly)
Greg you are regulating the amount of v/a going to the field coils of the dynamo,its just a vibrating pair of contacts really but i'm not sure that other factors could influence the setting .(i.e. state of battery charge or current draw)
I like the little mechanical box,I know it's fashionable to sling it and use an electronic one,but I've used a converter to raise the volts to 12 to power the lights and that's all you need. I'll wait a while and see if anyone can help and then if not will do what you did .

[keith.mettam]

Hi Bill,
I don't know what Lucas regulator was fitted to your machine but here are a couple of Lucas Service Manuals that may interest you and be of help:-

Lucas_Regulator_MCR2.pdf

(177.1 KiB) Downloaded 201 times

Lucas_Regulator_RB107.pdf

(125.73 KiB) Downloaded 202 times

All the very best,
Keith.

[greg.geonetta]

Hello Bill

I just looked up "mechanical voltage regulator" on YouTube and there were a few vids showing how to adjust one. I think they all are basically the same, auto, bike, tractor, etc.

I didn't get into the cutout relay but the video does explain that and how to adjust too. But the issue you describe with the ammeter going full negative when the lights are switched on is a common complaint for SQ4 owners. Mine does the same thing.There are several threads relating to the SQ4's weak charging system.

I just wanted to up the voltage a little so the battery is being charged at a bit lower road speed. I think it did help in that regard.
It didn't seem to make much difference when the lights are switched on, though. Ammeter goes full negative, and the engine speed must be higher for the battery to be charging(barely)

Yes the screws are preset from Lucas but you can still turn them. I used a digital voltmeter connected to the battery while the engine was running to see the voltage change. You only need to turn the screw a little to make a difference.

[bill.bottrill]

Thanks Greg,
I'm not too concerned about my problem at the moment,it's on a todo list.Your post just reminded me about it,I also then looked it up on the web.Although there are only a couple of adjustments it's quite complicated I reckon you need at least a couple of days to check everything out.For a start they don't recommend a digital voltmeter (unless you use it alot) because it dances about so much you need an old analogue one (I got one at our local auction house an AVO.£10 nobody wants them!.
Also which might apply to you as it's pretty hot for a 4 out there,If you look at the bobbin regulator it's got just a couple of turns of real heavy wire coiled around it and it's connected into the main output of the dynamo!What's the point of that i've always thought. Well it turns out that these dynamo's can get overheated on full output and its a temperature compensating coil which limits the dynamo output Now Lucas must have had problems with overheating as these compensation coils are on all cutout boxes
I'm sure just moving the screw abit isn't going to upset too much,I will unfortunately have to check mine out because of the discharge,it looks like somebody weakened it off a tad as my ammeter warning light should gradually come on around tickover(if I remember correctly)and it's only when it's stopped and restarted that it does light up
Also the amount of vibration from this 55 jobby,using a lead acid battery I reckon all the lead would be shaken off the mesh in the battery within a mile or two!.I have mounted my battery on a sprung frame within the dummy box
As so many owners have reported problems with the 6v system it's important to keep everything in tip top condition