Does anyone have any thoughts on using the Lucas 6v windscreen wiper motor on a Ruby converted to 12v. The starter motor works OK but that is only used in very short bursts and the trafficators are also OK with resistors in their circuits. The wiper motor SEEMS to be working well without resistors but will prolonged use cause problems. If so can anyone tell me what resistor i should incorporate into the wiper circuit. Electrics, generally speaking, are foreign territory to me!
Thanks in advance.

Location: Ossett, West Yorks.

I would fit an appropriately rated resistor of the same resistance as the motor itself in series with the battery feed to the wiper motor.
Unfortunately I don't have such a motor to hand so I can't measure it for you.
If you can measure the resistance of your motor (disconnected from battery) then I can tell you what wattage and resistance the resistor should be.


Ian Mc.

Location: Shropshire

Ian, you need to divide the running current of the motor into the voltage to obtain the value of series resistor but adding this resistor in series with the motor will severely limit the starting and running torque. A better solution would be either to rewind the motor for 12V or use a voltage regulator.

Does anyone know the approximate running current?

Peter

Location: Royston, Hertfordshire

Rather than prolong the thorny debate of 6 volt wiper motors running on 12V, I have to ask, why this enthusiasm to convert to 12 volt electrics anyway??

The 6 volt system worked well enough in period and, unless you intend regular, protracted night-time motoring, it copes adequately today.

Having said that, if I were to convert to 12 volts (which I am not), and I was someone to whom "Electrics, generally speaking, were a foreign territory!", I would source a compatible 12 volt wiper motor; they are more common than the 6 volt originals.

Sorry, I won't be able to stick around and argue the toss as, after tonight, I shall be out of the UK for the next month.
Good luck with whatever route you choose.

Ian Mc.

Location: Shropshire

I have been using a 6V wiper motor on 12v now for about 3 years, on and off (haha) It seems to work fine, I use it until the motor gets hot and then give it a rest. Actually Rainex means rarely having to use the wiper anyway. I think since the motor has a lot more torque on 12v it overcomes the struggle usual when on 6 volts and so does not have to slog away so hard (I am aware this is a totally empirical observation and without any scientific base)

It is similar to the results of the 6v fuel gauge, starter motor and horn used on 12 volts, all work better and seemingly with no harm.

I recommend the mods detailed on the Cornwall site, made by Sandy, which are very effective!

Regards Jack

Location: United Kingdom

Location: NZ

For me, the appeal of A7 motoring is its "quirkyness". I'll admit to tweaking the engine a bit, and to using QH bulbs in more efficient, more modern headlight reflectors but, I think, to go much further would be to totally lose the character of the car which is what appealed to me in the first place.

Ian Mc.

Location: Shropshire

John,
I have been using a 6v "Pull and Spin" motor on 12v for the last 10 years on my RN saloon with no problems.No resistors or other mods in the circuitry to the motor.
Cheers,
Dave.

Location: Sheffield, the home of Hendersons Relish.

Back to the OP, depends what you call prolonged use, I doubt if it will be more than a couple of hours, and if others have successfully used 12v on the 6v motor so be it.

However if you mean by Prolonged use, say Carlisle to Exeter, then on 6v, the casing does get warm/hot, although I was stopping for Coffee & Petrol every three hours, so there was a break of use.
So on 12v, I think you might be pushing it a bit. I have the later DW3's, not 'Pull and Spin' motors.

Yes, the last Jogle I was on, it rained all that way...

Location: On the very Edge of Europe....West of Jelbert, Brian, Alastair, Bob and everybody else..

Technically, the best way to run a 6 v motor on 12v is to copy the cordless drill method. "Pulse Width Modulation" or PWM. Something like this will do it nicely:
http://www.ebay.co.uk/itm/Pulse-Width-Modulation-PWM-DC-Motor-Speed-Control-Switch-12V-40V-10A-New-/231212669053?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item35d559587d. That one is only 99p!.ebay search "DC motor speed controller" for loads more.

This one does exactly the same and is already in a nice box : http://www.ebay.co.uk/itm/DC-12V-8A-Light-Dimmer-Brightness-Adjustable-Control-For-Single-Color-LED-Strip-/350970512495?pt=UK_Light_Fittings&hash=item51b779046f

For the non-electrikery folk it just means the 12v will be turned on and off extremely rapidly. When the motor is running at 6v speed the 12v supply will be ON for about the same duration that it's OFF. Of course you then have the option of running faster or slower. Hardly any wasted power and the motor torque will actually be better.

Just saying.........

Location: East of Sandy..Cornwall

Hi Roger

Tried the dimmer thing. works a treat, thanks for the tip.