Hints and Tips - Shocker Fluid

From: Charles Ping
Sent: 11 January 2002
To: british-cars-pre-war
Subject: Electrical Guru's Pay Attention!

Folks

What are the practical effects of running a 2 brush 6 volt dynamo on 12 volts? Assume that I change the regulator for a 12 volt version and do the usual bulb changing etc. What is the downside. What is likely to break?

Thanks

Charles


From: Stuart Roach
Sent: 11 January 2002
To: Charles Ping
cc: british-cars-pre-war
Subject: Re: Electrical Guru's Pay Attention!

I'm running an Austin 7 dynamo, converted to two brush from 3, on 12 volts and have had no problems and can actually see where I'm going at night and still have a good charging rate with all the lights on.

Stuart Roach


From: Charles Ping
Sent: 11 January 2002
To: Stuart Roach
cc: british-cars-pre-war
Subject: Re: Electrical Guru's Pay Attention!

Stuart

Are you just running a modern(ish)Lucas regulator with it or something more hi-tech and sophisticated?

Charles


From: Stuart Roach
Sent: 11 January 2002
To: Charles Ping
cc: british-cars-pre-war
Subject: Re: Electrical Guru's Pay Attention!

Charles

Im running one of Dave Lindsay's electronic gizmos and have had no trouble with it or my dynamo. I do drive my car continuously through the night on a few trials so it has been put to the test on many occasions in the past 10 years. The next conversion is some halogen headlights to really light up the road.

Stuart


From: Maggie Shapland
Sent: 11 January 2002
To: british-cars-pre-war
Subject: Re: Electrical Guru's Pay Attention!

I too am interested in this thread since I taking my Talbot back to Fougeres (lightening does not strike twice!) and will get off the ferry at Poole between 12 and 1am to then drive 70 miles. Currently just my sidelights on 6volt system are better than my headlights plus sidelights despite having bought halogen bulbs for headlights! As a first shot

I have just sent my headlight reflectors away for resilvering, but the lights are dim orange so may not have much effect. Discharge is about 15 with headlights on, about 0 when sidelights on. It may just be easier to go to a bed and breakfast if they are open this time in the morning!

When I drove back from Brooklands last time I found it easier to drive down the motorway following the white line on the side of the road but this is not very practical. I also get dazzled by oncoming headlights.

I am unlikely to over rev the car unless I am going up a steep hill- and I dont think driving tests are likely to over rev it as I am usually more interested in stopping in the right place and am able to change gear if the stretch is too long for first gear. Will the 6volt starter be affected?- but I usually swing it anyway since it does not work very well. I dont have a spare starter. I do have a spare switch panel with a 12v cutout but it may need refurbishing. How easy is it to add a third brush to my dynamo- I have just had my spare refurbished?

----------------------
Maggie Shapland
1925 Lanchester 21, 1925 Talbot 10/23, 1929 Peugeot 190S, 1986 Moss Monaco


From: TA Terry
Sent: 11 January 2002
To: Charles Ping; british-cars-pre-war
Subject: Re: Electrical Guru's Pay Attention!

In a message dated 1/11/02 04:56:19 Pacific Standard Time, Charles Ping writes:

<< What are the practical effects of running a 2 brush 6 volt dynamo on 12 volts? Assume that I change the regulator for a 12 volt version and do the usual bulb changing etc. What is the downside. What is likely to break? >>

Charles, I doubt that you'd be able to get enough field current into the 6v dynamo to make it generate 12 v and charge your battery, not withstanding the regulator........your reverse current relay will likely never close.......nothing will break unless you force the relay closed, then the 12v battery will burn up the 6v dynamo.......

Terry in Oakland


From: Bishop Peter-PBISHOP1
Sent: 11 January 2002
To: british-cars-pre-war
Subject: FW: Electrical Guru's Pay Attention!

Charles, is this for your competition car? I have run this conversion for 2 years. I did have problems early on, with excess charge currents when using abnormally high revs on trials coupled with low charging rates at normal "road" revs. Neither the NP1 type electronic regulator or the old Lucas regulators have suitable effective current limiting. I ended up modifying the design myself. If I did it again I think I would include a modern re-settable circuit breaker under the dash somewhere to disconnect the Dynamo in the event of high charging currents during moments of red mist, or in the case of trials, the bouncer standing on the starter button!

Pete


From: Ian Grace
Sent: 11 January 2002
To: Bishop Peter; british-cars-pre-war
Subject: Re: FW: Electrical Guru's Pay Attention!

While on the subject, can someone explain something about the third brush system for me. I have not been able to find a basic wiring diagram of the third brush system with summer/winter charge switch included. I believe that the main and third brush coils are wired in parallel and that the switch is located somewhere between +D and the positive end of the third brush coil. Is the third brush coil switched in or out for winter charge? Could someone clarify for me?

Many thanks in advance,

Ian Grace


From: Charles Ping [mailto:Charles Ping]
Sent: 11 January 2002
To: Bishop Peter-PBISHOP1
Subject: RE: Electrical Guru's Pay Attention!

Pete

Yes, this is for a car that will be used in competition and on the road. The real idea is to make sure that I can keep up at night and in general road use (where I tend not to use 6000 revs). I could live with a switchable system that cuts the power to the field coils for those moments when I know that high revs are on the agenda. Was your modified system electonically based or some more simple?

c


From: Bishop Peter-PBISHOP1
Sent: 11 January 2002
To: 'Charles Ping'; 'Maggie Shapland'
cc: 'british-cars-pre-war'
Subject: RE: Electrical Guru's Pay Attention!

It's electronically based using the NP1 regulator sold by the 7 workshop and others. I turned the charging voltage up, added a series resistor to limit the max current, and a fuse which blows when bad things happen.

I would suggest upping the value of the fuse to say a 15 amp fast blow, and adding a 10A circuit breaker as well. You could trip the breaker out before intended high revs use, or just let it pop out on its own. If the battery is fully charged, then even at 6000 revs the current probably won't exceed 10A anyway. However if its halfway flat then you can easily see 20 -30A which is where the problems start and the dynamo expires. I am also using a gel type racing battery which has a lower internal resistance that a conventional lead acid. Unfortunately that further exaggerates the variation in charging current with battery charge state.

I noticed Stuart mentioned that he gets a good charging rate when running at night with the lights on. The A7 dynamo is quite capable of producing high current outputs if you adjust the regulator setting to do it. It is not likely to last long however as you will eventually overheat the armature, and when running a 6V dynamo on 12V, the field current is also higher, producing even more heat. If you have not already done so I would suggest removing the brush cover band as this significantly improves the cooling. I have set my regulator to 14.5v which with my series resistance and a fully charged battery with all lighting (140W)on, delivers 10amps at normal road revs and hence shows no charge or discharge on the ammeter.

To answer Maggie's question a 6v starter will work on 12v it just turns the engine over twice as fast, perfectly OK if you only use it in short bursts. It will however draw a lot more current and if you leave it churning for 15 seconds or more, can overheat comutator segments and cause damage. If you want to convert to 12V then the preference would be not to use a 3 brush dynamo, but a 2 brush with independent connections to field an armature windings, making for an easy connection to a mechanical or electronic regulator.

With the current ( no pun intended) trends in automotive electrical systems, how long until we all start talking about converting to 48v so we can use next generation gas discharge headlight bulbs?

Pete


From: John Layzell
Sent: 11 January 2002
To: Maggie Shapland; Charles Ping
cc: british-cars-pre-war
Subject: Electrical Guru's Pay Attention!

I have been following this thread with interest. After about 20 mins driving, my charging climbs up to about +15-20 amps at 40/45 mph - 2250 RPM. This charging continues regardless of the length of the journey. Worried about blowing something, I usually turn the side or headlamps on to bring it closer to 0/+2/3

Do I need to worry about overcharging? System is 12V.

John Layzell
Miami, Florida
1925 Alvis SC 12/50 (with original FWB) - oldest Alvis in North America


From: Charles Ping
Sent: 11 January 2002
To: Maggie Shapland
cc: british-cars-pre-war
Subject: Re: Electrical Guru's Pay Attention!

Maggie

The world record for lightning strikes is one chap who's been struck 7 times! Still confident?

c


From: Maggie Shapland
Sent: 11 January 2002
To: Charles Ping
cc: british-cars-pre-war
Subject: Re: Electrical Guru's Pay Attention!

I'm a positive thinker else I would never use a vintage car again! I have to prove a point with the Talbot and perhaps the following year it will be the Lanchester- bit bigger to run into and harder to get out of the way. Anyway I have never been struck by physical lightening as opposed to phraseological lightening

----------------------
Maggie Shapland
1925 Lanchester 21, 1925 Talbot 10/23, 1929 Peugeot 190S, 1986 Moss Monaco


From: Maggie Shapland
Sent: 11 January 2002
To: british-cars-pre-war
Subject: Re: Electrical Guru's Pay Attention! charge rate

my 6v car has been charging 20 amp + for last 30 years with no damage to dynamo, turning to nao charge has no effect- the only damage caused to my other defunct one was getting oil inside it and cooking the wires. When the dynamo was fixed after the accident (the core was shorting on the casing due to the jolt) they tried to get it to charge less but couldnt. The Lanchester, which is 12v is about 10 amp if I remember so I cant comment on 12v. On Fri, 11 Jan 2002 Johno8 wrote:
>
> Do I need to worry about overcharging? System is 12V.
>
> John Layzell
> Miami, Florida
> 1925 Alvis SC 12/50 (with original FWB) - oldest Alvis in North America
>

---------------------- Maggie Shapland
1925 Lanchester 21, 1925 Talbot 10/23, 1929 Peugeot 190S, 1986 Moss Monaco


From: Dave & Diana Dwyer
Sent: 12 January 2002
To: british-cars-pre-war
Subject: Re: FW: Electrical Guru's Pay Attention!

Ian On our prewar MG the circuit is as follows:

Cutout to main brush positive, through armature to ground. Control runs main brush positive - switch - field winding - third brush - thence through part of armature to ground.

Cars which have High/Low charge as opposed to charge On/Off will have a resistor wired across the switch (ie the switch shorts out the resistor for high charge).

The third brush is always in circuuit because that is used to adjust the charge current.

Regards

Dave Dwyer MGJ2, TA, TC


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