6V Ducellier regulator advice? (Dauphine era)

[JonE]

I seem to have three terminals, BAT, DYN and EXC. 
The Renault diagrams seem to suggest DYN and EXC go each to the two dynamo poles.
This Seven is charging with a 1929 dynamo and yet the EXC is not connected... both wires from poles end up at DYN.
Can anyone advise/explain? 
I'm less fussed about investigating whether its 3 or 2 brush now I know its working, but I'd like to understand why!

[John Cornforth]

Hi JonE

EXC is "Excitation" in French which is the Field winding to you and me.  The Ducellier regulator box will have both a cutout and a voltage regulator section, the latter is intended to drive the field winding of a 2 brush dynamo to give a constant (regulated) output voltage.

I suspect that your dynamo is a 3 brush type, and the join between the main output and the field winding will mean it is permanently set for maximum output.  If this is the case, only the cutout part of the Ducellier regulator is being used.

You mention three connections, but there is of course also an essential earth connection via the mounting screws.

["Slack Alice" Simon]

EXC = "Exciter" ???   Ie. Field Coils ???   If so, shouldn't work?????

[JonE]

exactly, Simon. John - thanks - but what if the EXC isn't connected to anything? I can see this needs sensibly converting to 2 brush (or swapping with a later less rare dynamo) but could it still be maximising output.... if there is no link to that EXC?

p.s. anyone know for certain which DEL Dynamo terminal is the D and which the F? (as it's unclear in the Cornwall Refresher). I'm presuming the latter is the smaller one of the two but would like to know for sure.

[Bob Culver]

There is nothing inherently wrong with the DEL dynamo. It has the luxury of a ball race at both ends. Unlike the later it is a 4 field pole device and the main brushes are at 90 deg to each other which can lead to lots of confusion. One main brush is connected to earth. The other directly to the output terminal. This should be traceabe although you may need to stand on your head with a torch and mirror. The field brush wire disappears into the innards to connect to the filed winding, the other end of which connects to the F terminal.
If the two stages of charging not required ithe F terminal can be connected directly to the main brush output. This is effectively your situation. Presumably the 3rd brush is still in operation otherwise difficult to avoid excessive output, more than about 8 ammeter amps.
Attempts to eliminate the 3rd brush and utilise the regulator function of the presumably 6v regulator are fraught and more so with 12v, although I see no reason why the 6v electromechanical regulator if the innards suit could not be run utilising the 3rd brush. Some claim the switching action rattles the timing gears .
The regulator does not increase output which must be lept to about 8 amps max on the ammeter no load; but it should avoid overcharging.
(The DEL origianally had a hidden internal summer resistor but this is usally now open circuit. If still there would compromise a regulator as could not reduce below the summer rate.)

[JonE]

Bob - this is very useful but brings up more questions too! It is an interesting situation as morally, whereas I was initially thinking I needed to be rid of the 60s unit, I realise that the Speedex IS a 1960-created car despite its old underpinnings - it is part of the car design from that period.

I was presuming all 2 brush systems remove the 3rd brush precisely because it became extraneous, but I'm reading your post as if "DEL are complex so just leave be"? And indeed, with modern headlight bulbs, not having max output, for some reason, isn't perhaps a great problem.

The 'fraught' bit - is that just because of timing gear rattle or are there other reasons?

I'm still wondering about my lack of present connection to the EXC/Field post of the regulator though - and its implications.

As it is, I'm thinking of removing the wire from BAT on regulator and moving it to EXC, whilst connecting the two dynamo posts. And seeing what happens?

[John Cornforth]

Hi again JonE

Somehow I haven't made myself clear in my post above. I am pretty sure (cannot be 100% without seeing it) that you have a 3 brush dynamo wired with its main output and field joined, which will function more or less as designed at its full (winter/headlights) output. Voltage regulation (of sorts) is taken care of by the 3rd brush, no external regulator is needed, just a cutout.

The Ducellier regulator is a red herring. I suspect someone in the past couldn't get hold of an original 6 volt cutout, so they are using just the cutout part of this. The regulator part (which only suits a more modern 2 brush dynamo) isn't needed and isn't being used.

I'd be wary of swapping connections just to see what happens, especially given that the present setup appears to be working.

[Bob Culver]

Hi Jon

The fraught applies to all models, due the field being intended for just 4 or 5 volts.. Been extensively covered in the past. The only complexity of the DEL is the internal resistor if still intact, and your wiring effectively bypasses it anyway. Whatever, as with all the dyns, keeping the output within accepted amps is the main consideration.
At least for those without a full grasp of the workings I very strongly concur with John's recommendation.

[JonE]

ok thanks both. Will familiarise myself with DEL third brush so can work out how to quickly trim manually.

I'm intrigued about the regulator's EXC terminal (what can go wrong if I try?) but will try and resist until I've solved other more pressing problems!

[JonE]

This particular system has forced a complete re-read of all the Forum threads on charging, 12V and the various posts from people like John, Bob and Ian Williams on general circuit "efficiency" of what Austins originally proposed.
Firstly, no sense in questioning the present 6V with modern bulb availability. In this car, there IS a 6V Smith fan which doesn't seem to have a great current draw and likewise, a 6V-12V converter-supported cheap auxiliary water pump isn't seen to have huge consumption. Both (thanks Grieg and Robert) can be independently manually switched according to the temp gauge (and whether steam is emitting).
I'm going to ditch the electromagnetic cutout box as I'm advised not to use the regulator side - and the TI solar chip now sold by Magnetoguys (and available for about a fiver as the direct chip) is THE presently most-efficient cutout, and even smaller than the shotky diode. A spare, as shotky, is easily carried. In fact, I'll just carry the spare Shotky I have.
I'll use a https://www.ebay.co.uk/itm/6v-12v-24v-Pr...XQVT9S2Hr5 to better alert to having to use the (efficient) third brush control and just leave the dynamo cover off.
What I'm still head scratching over is the level of electrical efficiency for the summer charge systems and whether they can be entirely replaced just by moving the third brush, albeit this being considerably less convenient. Bob brought up the lack of ultimate efficiency for a potentiometer/variable resistor or external bulb approach (see thread on potentiometer) so I'm presuming it is just weighing up convenience versus theoretical losses - or is the latter affected by WHERE the applied resistance is located in relation to the dynamo position?

Where do the best electronic regulators sit in all this, presuming that they don't have the potential effect for rattling timing gears which has been mentioned for electromechanical switching control? i.e. Accepting that they are all removing the third brush which is being proposed as the most efficient regulation of all? My personal decision not to use is more from the sense to carry a spare and the gradual realisation of the need to worship the original third brush, but I'm still wondering how their "modern" function fits...