Classic cars forum & vehicle restoration.

[1stpop]

could someone please tell me what are the pors and cons of this type of conversion? - is it a good idea? does it improve anything? and finally - is it easy?

[Rick]

Welcome to the forum 1stpop!!

As a former E83W owner, I found 6v perfectly good enough for the job so long as everything is in decent nick, good sound electrical connections and so on. I've heard sidevalves spin over on 12v and it sounds like they are going into orbit, all a bit unseemly with something of a certain age

Any reason why you're toying with converting?

Rick
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[pigtin]

Hi, I came across an unusual mod carried out on a VW a few years ago
An 8v battery was fitted to a 6v system, (yes you can get a 12v battery with a post in the 8v position) the beauty of it was that all of the original lamps, the starter and dynamo can be left in situ'.
The theory is that headlamps etc' never end up with the full 6v from the battery owing to drop along the wires at such a low voltage, and even using 8v you will still end up with little more than 6v instead of the usual 4.5-5v you would receive normally.
The dynamo is perfectly capable of supplying the extra voltage for charging purposes, although you will have to make a small adjustment on the regulator.
The starter motor is perfectly happy and spins faster, so you end up with better starting and lighting for the price of a battery and one small adjustment.
I carried this mod out on my previous Austin 7 special and it was a 'revelation' I could actually go out in the dark and never needed the starting handle. The only thing that worried me slightly was the voltage reaching the coil, so I put a diode in series to drop it by 0.6v.
Alternatively I believe the "modernish" coils which work with a ballast may be of a suitable voltage. (without the ballast of course)

The original article appeared in the 'Karman Ghia type 3' club magazine and I still have it somewhere. I would have thought a 6v Ford Pop or similar would be ideal for this conversion and it seems to work as well as a 12v conversion, for a fraction of the price and hardly any work.

Don.

[Rick]

Coincidentally I put this old pic on the main site a couple of days ago, showing a Pop in its prime..



Rick

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[Uncle Joe]

This is a conversion that I would do, if possible. Well worthwhile just for starting alone.

It does take some thinking about to do it properly though, because there are some pitfalls.

UJ

[Rick]

I assume the following parts would either need replacing, conversion or adjustment at the very least?

- dynamo
- regulator
- bulbs (inc dash)
- feed to fuel gauge
- coil
(the starter will probably be ok in short bursts)

to be honest I wouldn't bother with 12v, but thats just me pigtin's 8v upgrade sounds like a good inbetweeny choice

Rick
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[Uncle Joe]

Rick, I can understand your reasoning on this.

For gauges and things, there are 12 to 6V converters available. Another thing that I would think of doing at the same time is convert to negative earth, but only if possible, because that does cause problems.

I would expect though that this should be a relatively easy conversion on a Pop, but may be wrong....

UJ

[pigtin]

Rick, I think you could be seeing some problems that may not be there.
I believe that the dynamo's output is controlled by the regulator switching in a resistor to weaken the field when the voltage exceeds around 7.25 and even in the case of the humble Austin seven the (three brush) dynamo was capable of producing in excess 12v when not constrained by a 6v battery.

In the case of the VWs no problems were experienced with the smaller lamps, probably because the voltage remained reasonably close to their upper tolerance. There would, of course, probably be a shortening of their lifespan; but that is unlikely be significant.

Not sure about the fuel gauge, the problem was not mentioned in the VW writeup and my seven didn't have one; but the effect of the exta voltage may be minimal and if an instrument regulator is fitted (were they on older 6v cars) it may take care of it. Alternatively you could fit a zener diode and resistor for a few pence to provide regulation.
One or two diodes in series with the supply to the coil alleviated my worries about the coil on the Austin, but as far as I know nothing was done on the VWs.
Windscreen wipers on a Pop would be vacuum operated but I don't think the effect on an electric one would be significant.
The theory behind this conversion was that an extra 2v, while giving many advantages, is still (in the case of the VW and Austin 7) just inside the upper limits of the components supplied.

Almost forgot the starter: Starters are said to be current operated devices and increasing the current increases the speed, my Austin Ten has had 6v starters running on 12v for over twenty years and I have never had an electrically related problem with them. An extra two volts will only make them turn a little faster and should not have any detrimental effect (on Joe Lucas ones anyway).
Don.

[1stpop]

thanks for the advice so far... knew it was a good idea to join this site!! the 8volt idea sounds to be a winner because I don't really want o have to start doing a lot of work on what is a sound system (at the moment). Just had a little problem with the starter motor, but it starts 1st time with the handle.

My real concern was the lights - not too bright but the 8V solution may help with this..

[Rick]

sounds interesting, are 8v batteries available with the old black rubber cases? I've never seen (nor looked admittedly!) for 8v car batts.

Rick

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[pigtin]

We are going back about eight years now to when I bought mine from a local (Canterbury) battery specialist. I think it came from 'Lincoln Batteries' in South Essex somewhere; they advertise in the motoring press.
There may be a problem with size: It is an old style 12v black battery with exposed straps between the cells and an extra post welded in the 8v position so it can be used as an 8 or 12v battery.
It would just fit into the VW battery compartment, but it may be wise to check with the suppliers for size and availability.

Don.

[Uncle Joe]

All of the advice given is sound, very sound indeed. I do like your reply, pigtin!

But (isnt there always!) dont forget that its a lot easier to get hold of 12v parts (batteries, bulbs, etc.) than 6v. What happens, say if you want to fit a radio at a later date if you dont have one now? Or some other accessory? A 12v upgrade makes the car more modern and reliable, does it not?

I would say, go for the 12v first, or, at least investigate it properly. Then and only then, look at the 8v idea.

Maybe I shouldnt comment on this though, I'm looking at converting one of mine to 16v!


UJ

[UKdave2002]

Hi all

First post for a while, and sorry I’m going to be a bit challenging here , but some of the advice in this thread is really not electrically sound.

Ok you can convert your vehicle to any voltage at all, as we know 6v & 12v common in cars 24v & 28v in commercials. But IMHO moving away from these standard voltages will give you future problems, as all the electrical gear you are retaining has been designed to work at a certain voltages and you will put some devices beyond reliable tolerances.



Here are a few facts;

Advantages of using a higher voltage
You reduce the current flow, so can use thinner cables, and have less wear on electrical contacts.
The big advantage is starting and you have to understand a bit about batteries; with out getting too technical a characteristic of all batteries is that they have a small internal resistance, say 0.02 Ohms for a lead acid, what this means is that a 6V battery (not being charged) that has a 10amp load (about what headlamps require) will loose 0.2volts across the battery (10A x 0.02Ohms) so will deliver 5.8 volts to the headlamps. In reality the generator will be charging the battery so you will have the full 6v, if you are not getting 6v at the bulb you have a fault, you certainly should not loose 1.5v in the wiring .

Starting
When you start a car this internal battery resistance becomes really important as the currents are much higher, and we won’t have any charging system at low revs.
So for example if the starter motor is drawing a 100amps we will now have a 2 volt drop across the battery (100A x 0.02) so the starter motor will only have 4V across it, if it’s a cold day or the battery is past its best things will quickly get worse, a 12v system will half the amount of current required to turn the starter and more or less halve battery related starting problems.


The Regulator
The regulator, regulates both current and voltage and allows for a higher output to charge the battery quickly, whilst at the same time not blowing bulbs, this is why they can’t just regulate voltage. Actually older simpler regulators did this and the driver had to select high or low loads manually. To charge an 8v battery the regulator would need to be set to about 9.3v, it could be done (but why!!)

Bulb life
Manufactures design bulbs to operate at 6.75v for 6 volt systems, if you left these bulbs in your 8v system they would be about running about 30% higher than their design, which would give you over 200% light output but life expectancy would be below 10%.

The Coil
The important thing with a coil is the speed at which the field collapses more than the primary voltage (whole different subject), but for reliability’s sake I would add a suitable wire wound ballast resistor if moving from 6 to 8v (in this case the ballast resistor should be about 30% of the value of the coil resistance), yes a silicon diode does have a forward voltage drop of about 0.7V, but a resistor is far more robust, and you can get the drop spot on.

Gauges
To convert them from 6V to 12V; measure the resistance of the gauge coil, then purchase a resistor of the same value (should cost less than 10p) and put this resistor in series with the gauge. If you really want to go from 6V to 8V the resistor needs to be a third of the resistance of the gauges coil.

If you want to move from 6v, to maintain reliability and keep the conversion simple, my advice would be move to 12v,

change ;

The generator
bulbs
flasher unit
regulator
horn

Modify

the gauges by adding a resistor
the coil by adding a resistor

Keeping the 6v starter motor is ok, as long as you don't use it for prolonged periods I have done a couple of 6 to 12v conversions for mates, and not had a problem with leaving the original 6v starter motor in (it does spin a tad fast tho!).

My Morris is fine with its original 6V electrics, however if I had to use it as an everyday car driving at night in winter I’d change it to 12V

UJ I'm really intrigued as to why you want to move to 16V


Cheers Dave

[Uncle Joe]

UK, for better starting, its as simple as that! I've was looking at some 16 volt batteries a while ago, and noticed that they had 3 poles, earth, 12v and 16v.

I know that I can get hold of suitable starters and generators, so Ive started looking into things, to see what it entails.

UJ

[UKdave2002]

UJ

If you can get a 16v generator and starter motor it’s easy, run the rest of the car off the 12V side, the battery will regulate the 12v for you and you won’t have to change anything else.