6v Regulator for a Generator System

[Les Jones]

Is your regulator attached to the dynamo as it appears to be in the picture on page 10 or is it remote from the dynamo and connected with the red and white wires as shown in your wiring diagram ? If it is remote then disconnect the red and white wires from the regulator and measure the resistance between each one and ground and the resistance between them. Also record the reading you get when the test probes are touched together so we can subtract that amount from your three resistance readings.

Les.

 

[sign216]

Les,
The regulator is remote, attached by the red and white wires as shown in the wire diagram.

Taking the readings here will save me a ton of work, as well as the risk inherent in taking apart a 50yr old system.
I'll get the readings later on.
Joe

 

[sign216]

The resistance measurements:
red to ground = 0
white1 to ground = 0
white2 to ground = 0.75
red to either white wire = 0
probes together = 0.35

Attached is also a photo of regulator label, with it's data.

 

[alec_t]

I also think the picture at the top of page 12 has the voltage and current coils labelled the wrong way round.

My thoughts too. The coil with the heavier wire gauge would be the current coil.
Given the inconsistency between the Benelli diagram and the BMW article I wouldn't like to trust either! Dismantling would provide a definitve answer.

Edit: Just spotted your latest post.
That regulator label settles it: the field winding definitely connects to D+ and not to ground.

 

[sign216]

I would trust the Benelli diagram and the voltage regulator info. I referenced the BMW material only because there's very little on the Benelli, and I thought it would help.

If the field winding connects to D+, then what's the next step? Can you adapt this schematic for a 6v system? Is this schematic even suitable?
Optimally, the electronic regulator would have the features of the mechanical regulator; voltage regulation, over current protection, and preventing the battery from bleeding through the dynamo when the engine's off.

 

[Les Jones]

Hi Joe,
I do not understand the TWO white wires. Your wiring diagram and the diagram on the regulator only shows two wires going to the dynamo. (I assume the ground just connects through the frame.) There is something wrong with your resistance readings. If you have zero ohms between red and groubd and and zero ohms between red and either white wire then how can one of the white wires (White 2) read 0.75 ohms to ground. Also there must be a short to ground on the red wire as it should only connect directly to ground via the contacts on the regulator and as it is not connected to the regulator it should read resistance of the field winding in series with the armature resistance. (Possibly in parallel with the resistor shown in the diagram.) Did both white wires connect to the D+ terminal on the regulator before you disconnected them ?

Les.

 

[sign216]

Yes, both white wires were joined at the D+ terminal on the regulator. Looking at the Benelli wire diagram, one when to the D+ at the generator, and the other went to a switch. Judging, it looks like the combination horn/lights switch.

I think the red wire might be correct, depending on whether the horn and/or stop light is depressed when the reading is taking place. Am I looking at that correctly?

 

[Les Jones]

As you have the red and white wires from the dynamo disconnected at the regulator end then the position of anything cannot effect the resistance readings.

Les.

 

[sign216]

I took another look at the Benelli diagram and my readings.
The red wire is also connected to the brake light. Before I got no connectivity to ground. But if I test at the brake light switch, then the red wire has 0.5 ohms to ground.

The white wires are the same. I looked at the wire diagram, and fooled with light switch, but it's the same. No effect. One white wire has no connectivity to ground, and the other has approx. 0.75 ohm to ground.

 

[Les Jones]

I'm confused. Acording to the diagram one end of the red wire connects to the Df terminal on the dynamo. The other end was connected to the Df terminal on the regulator until you disconnected it to do the resistance measurments. You now say it is also connected to the brake light.

Les.

 

[sign216]

I'm confused. Acording to the diagram one end of the red wire connects to the Df terminal on the dynamo. The other end was connected to the Df terminal on the regulator until you disconnected it to do the resistance measurments. You now say it is also connected to the brake light.

Les.

I see what you mean. I saw only one red wire at the regulator, which must have been the one to the brake light. I'll look for the other red wire going to the dynamo.

Also, I'm referring to the Benelli wire diagram (Post 27) not the diagram on the Bosh regulator.

 

[sign216]

Les, I give you credit for your sharp eyes.

There was a second red wire, attached underneath the regulator. Perhaps this is the one to the dynamo. The resistance to ground was a mere 0.002 ohm.

 

[alec_t]

I'm also confused, not least by the main 3-way ignition-switch operation.
One end of the wire going to the stop-light switch is green and the other end is brown!
The generator and high beam indicator lights have been transposed!

Can you adapt this schematic for a 6v system?

I now have reservations about that schematic and think it needs completely re-designing, rather than just adapting. Firstly, the field winding connection doesn't match what your generator has. Secondly, a lot of heat will be generated unnecessarily by current-sense resistor R5. Thirdly, unless there is a fair bit of residual magnetism in the generator it may not provide enough output to bias Tr2 into conduction so will never boot itself up properly. Fourthly, although the generator output is current-limited the charging current for the battery may not be adequately controlled so the battery may cook. What are your battery specs re maximum charge rate?

 

[sign216]

Alec, I'm just a beginner. The generator is 6v and 60 watts. The stock batttery is 9 amp hr. Does that help?

 

[Les Jones]

I think you would be better sticking with the original regulator. I do not have enough confidence in any of the information to design an electronic regulator.

Les.

 

[alec_t]

The generator is 6v and 60 watts. The stock batttery is 9 amp hr. Does that help?

From those figures I conclude that the generator current should be limited to 10A maximum (actually less, to allow some margin on the assumption that the manufacturer's figures are a tad optimistic and the conditions under which 60W is obtained are not known).
"9Ah" tells us the ideal battery capacity, but does the battery have marked on it the maximum charge current (or can you provide a link to its datasheet/spec)?

I do not have enough confidence in any of the information to design an electronic regulator.

I'm prepared to have a go, but at the OP's risk that it might not work fully as intended (since there are several unknown parameters) and provided that the OP's insurer is happy to accept a DIY regulator.

 

[sign216]

Gentlemen please give it a try. If you remember, a year ago you gave me a circuit for an antique motorcycle with an AC 6 volt system. Your circuit then worked beautifully and made the bike functional once again.

The battery for this bike has no specifications other than 9h and 6 volt. The stock battery is quite small, much like one would use for a lantern battery or for a small lawn tractor.

Don't worry about the insurance company. Here in America, insurance companies do not care.

 

[alec_t]

From this page it looks like the recommended max charging rate is around 1.1A for batteries of comparable size to yours. I'll use that figure for design purposes.
I'm no biker. Can you describe what the three positions of the main (top left) switch do? (I assume one position is 'everything off').

 

[Les Jones]

Hi Alec,
The main thing that concerns me is that the resistance reading on the red wire from the field that supposedly was disconnected from the Df terminal the regulator is zero ohms. I cannot imagine the field current being greater than about 1 amp so it should show at least 6 ohms to ground.

Les.

 

[alec_t]

I've lost track of which measurements were made between which wires with/without the generator and regulator being connected/disconnected .
It would be nice to have confirmation of accurate resistance measurements for the generator main and field windings without the generator connected to anything, i.e the resistances (1) between D+ and the generator body, (2) between the D+ and Df terminals as shown in the bottom right section of the Benelli pic.

I cannot imagine the field current being greater than about 1 amp so it should show at least 6 ohms to ground.

I've run a rough Spice simulation. If the field winding is assumed to have an appreciable inductance of 0.5H or so and the regulator can switch the field current rapidly then the average current is a good bit less than Ohm's Law alone would suggest.