6 to 12v conversion

[arcturus]

Hi again I have decided to bite the bullet and the conversion at the same time as rebuild. Sourcing a dynamo, regulator and blower motor. Ron,will contact you regarding the converter for wiper motor. Horn,I have a spare 12v. will I need to change the relay?

[Ron Kwas]

Arcturus;

6V Relays should be changed when going to 12V, as they will likely overheat with double V applied. See also: https://www.sw-em.com/Ignition_Slave_Relay.htm#momentary_vs_continuous_d uty_relays

...if you cannot locate a 12V Wiper Motor (first choice!), running the original 6V unit with a Dropping Resistor is always an option. I'm sure you've seen this, but here is the link again: https://www.sw-em.com/Vintage_Volvo_6V_to12V_conversion.htm

...there is even some of your 12V converter info posted there, but this is for low current loads up to 2A...I expect these modules would not have an adequate output for the Wiper Motor...you could make some current measurements to verify (and remember: Motor current increases with mechanical load).

Cheers

[arcturus]

Ron ,would the DR's shown be up to the job of running wiper motor. Changing to a 12v means taking off dash which requires in turn removal or wind shield.If so do you have any spare.Send PEM with details if you can oblige,or details of where they can be obtained.

[arcturus]

Managed to locate most of the stuff. I will need to stick to the original start motor as the 12v doesn't fit or so I have been informed. I hope it doesn't knacker the solenoid.
Ron,does the full current run that or is it like a relay,a switch?

[Ron Kwas]

arcturus;

Preferred first option is always to replace 6V components with 12V, and many of these exist because later Volvo models also went to 12V. If you cannot locate, or have another reason for not changing to the 12V version, DRs are the second choice, and yes, one could be installed for the Wiper Motor (although removal from an Amazon does not require glass removal and is otherwise not unreasonable...I can't speak to level of difficulty removing Wiper Assy on 544).

For answers to other questions, I refer you back to the article and notes, including reports of first-hand experience.

Cheers

[arcturus]

I have sourced all the components required including wiper motor. I have been informed that the 12V starter won't fit. not sure if I can swap a solenoid from a 12v. They look as though they are permanently attached. Would the 6v solenoid burn out? Is there a way round this?

[thx569]

I've worked in bench electrical on starters, gens, alts, carbs, etc for a few years. It is possible to rewire a 6v to 12v. I don't know who or where you might get this done in your end of the planet. Call around to auto electric rebuild shops. Solenoid may not be the issue. Starter drive pinion may blow first.

I upgraded my 1950 Plymouth a long while back with good success. Used a resistor at the fuel gauge. Had to change lite bulb sockets front and rear. I didn't bother changing the instruments bulbs - just turned the dimmer rheostat to lowest setting, bulbs were still very bright. New 12v blower motor and generator/regulator. I left the starter alone at 6v. Spun the engine over very easily (and fast). Blew the started drive after a few years. Carried a spare 6v starter in the trunk just in case.

[arcturus]

Re' fuel gauge .Where exactly should the resister be fitted? Is it in the supply from fuse or from sender unit?It talks about fitting externally to the instrument panel. It's a bit unclear.

[Ron Kwas]

Arcturus;

In series with Ign Power supply to Instrument, and external to Inst is fine (IOW, Inst does not need to be removed to add DR...you could simply add it externally, between supply [there are multiple wires as terminal is used as a common tiepoint] and Inst power terminal).
Like so:
https://www.sw-em.com/DR_12V_Fuel_Gauge.jpg

See also: https://www.sw-em.com/Fuel%20Gauge%20Notes.htm#drehspulinstrument_data

Cheers

[Laird Scooby]

I have sourced all the components required including wiper motor. I have been informed that the 12V starter won't fit. not sure if I can swap a solenoid from a 12v. They look as though they are permanently attached. Would the 6v solenoid burn out? Is there a way round this?

Have you sourced a 12V dynamo? If not, consider a Dynamtor :

https://simonbbc.com/charging/dynamator/

It will give you an alternator output from a dynamo shaped component, retaining the original looks but giving you the output you need to keep everything charged.

Would i be right in thinking you're converting to negative earth as well?

To answer your question about the starter solenoid, i'd strongly advise changing it to a 12V solenoid, the starter motor you'll probably get away with but if you can find a 12V one that will fit, use it! Failing that, get yours converted to 12V ideally.

[arcturus]

Not converting to neg earth. The dynamator is something for the future.My pockets are not very deep. I will probably fit a DR to solenoid.Get the system up and running first.

[arcturus]

Arcturus;

In series with Ign Power supply to Instrument, and external to Inst is fine (IOW, Inst does not need to be removed to add DR...you could simply add it externally, between supply [there are multiple wires as terminal is used as a common tiepoint] and Inst power terminal).
Like so:
https://www.sw-em.com/DR_12V_Fuel_Gauge.jpg

See also: https://www.sw-em.com/Fuel%20Gauge%20Notes.htm#drehspulinstrument_data

Cheers

Thanks Ron. I expected that to be the case. Just wanted to be sure.So the resistors won't affect the rest of the circuit? It could actually be installed at fuse box?

[Laird Scooby]

I will probably fit a DR to solenoid.Get the system up and running first.

It would probably be cheaper to fit a 12V solenoid and have done with it.

https://www.autoelectricsupplies.co.uk/product/1111

Most solenoids take about 30A to pull them in and a bit less to hold them so you'd be looking at a 0.4 Ohm resistor to drop the voltage. Becauses of the current involved, that resistor would need a power rating of around 200W which won't come cheap.

https://uk.rs-online.com/web/c/passive-components/fixed-resistors/panel-mount-fixed-resistors/?searchTerm=200w%20resistor&applied-dimensions=4292049435

Choice of 6 there, ranging from about £21 upwards. In other words, about 50% more than a new 12V solenoid!

[arcturus]

Solenoids are not interchangeable.See attached
the full article. https://www.sw-em.com/Vintage_Volvo_6V_to12V_conversion.htm

[Laird Scooby]

Solenoids are not interchangeable.See attached
the full article. https://www.sw-em.com/Vintage_Volvo_6V_to12V_conversion.htm

At the end of the paragraph before the one you've highlighted, it says "The solenoid on the other hand doesn't have the ability to withstand a doubling of the operating voltage for too long...and so it should be replaced with a later 12V type. I believe these are physically compatible"

In other words, exactly what i suggested in my previous post!

Just for clarification, it is an inertia starter with a separate solenoid and not a pre-engaged starter with the solenoid piggy-backed onto the starter motor body?

As for using a dropping resistor for the instruments, have you considered using an LM7805 5V voltage regulator with a couple of 1N4001s in series with the common (0V) leg to give 6.2 - 6.4V?

Much nicer than DRs for each gauge and more reliable with less heat.

[arcturus]

Piggy back and not interchangeable. From conversation with others the solenoid doesn't present too many problems. I think that Ron will confirm this.

[Laird Scooby]

Pre-engaged then. I don't see why you can't find a 12V replacement starter complete.

Oh well, it's your car, your effort, your money, you do what you want but i wouldn't want to run a 6V starter on a 12V system, it won't last long but could easily catch fire.

[arcturus]

I inquired about a starter from B18 but doesn't fit but thanks anyway for all your suggestions.I may have a look at the resistors.I was thinking about connecting through my Dale 50 watt but not sure about that. The ones I have connected up to wipers, two il parallel connected in series to wiper motor,obviously not good enough.

[arcturus]

Ron, re fuel gauge, Is this the sort of thing that's required (just a dummy experiment) taking the wire from fuse box. (easily accessible) ? Have i understood it correctly?

[Ron Kwas]

arcturus;

I don't quite understand your question, but essentially, you need Ign power to supply the DR, and this in-turn supplies the Instrument. Where you get Ign power from is non-critical, so it could certainly come from Fuseblock, but since Ign power wires need to be removed from Inst. anyway, they are (already!) right there, so it makes sense (is simplest!) to reuse them to supply DR, as shown in my sketch.

I hope that answers your question, and makes it a bit clearer.

Cheers

[arcturus]

arcturus;

I don't quite understand your question, but essentially, you need Ign power to supply the DR, and this in-turn supplies the Instrument. Where you get Ign power from is non-critical, so it could certainly come from Fuseblock, but since Ign power wires need to be removed from Inst. anyway, they are (already!) right there, so it makes sense (is simplest!) to reuse them to supply DR, as shown in my sketch.

I hope that answers your question, and makes it a bit clearer.

Cheers

My plan is to splice in the DR at the wire as shown where it connects to the fuse box as it is easily accessible there. Trying to do so at the instrument is a real PITA as it's tucked up behind the dash where you can't get at it. That was what I was trying to ask in a previous post if the other things which the power serves, ie the oil pressure light and the directional signal impulse unit would be affect by the DR being there.I hope that makes it clearer. My previous post with the photo of the connection was to confirm that the method of splicing was acceptable

[arcturus]

Completed all conversion to12 volt except for battery.Previous 85 amp. confirm that replacement 12 volt still 85 amp please.

[Derek UK]

Basically, whatever you can get that fits bearing in mind that the PV battery shelf isn't very deep. Extra amps always good but having them available for cold weather starts shouldn't be a problem for you. Terminal post position and +/- orientation has to be considered.

[Laird Scooby]

6V x 85A = 510W

510W / 12V = 42.5A

I'd suggest a 45A/h battery or slightly above, anything up to 60A/h would be fine but make sure your dynamo/alternator has a decent output in A to cope with a bigger battery.

If i knew what dynamo you currently have, i could probably suggest an alternator conversionbut that would almst certainly need a negative earth conversion too.

[Ron Kwas]

Arcturus;

I'd see about fitting a 60AHr (which is rating called for in the manual for a 122...don't know about a 12V 544!), but if it is difficult fitting this, you can certainly go with a lower AHr rating which will make Battery smaller...that just means less Starting Reserve energy available, but you're in a warm area where you are not cranking at well below freezing...heck, auto-crossers, where it's all about weight, install tiny motorcycle Batteries, and Start on a Helper Battery in the pits before a run...don't forget, once spinning, the Alt supplies ALL energy needed by the car's systems, and any output capacity left over serves to charge Bat, so varying the size of Bat doesn't affect much at all while driving...it only determines how fast Alt output brings it back to fully charged...[the smaller AH rating, the faster the energy bucket is refilled]. See also: https://www.sw-em.com/Battery%20Notes.htm#critical_battery_parameters

I do recommend ~60A output rating (and no greater) for the Alt, be it a Bosch with integral VReg, (like from a 240 Series) mounted on cast-in Pivot on late B18, or all B20, OR an added-on Bracket, which ipd supplies. See: https://www.sw-em.com/altkit_additional.htm#Generator_and_Alternator_Mou nting_Provisions_on_B18_and_B20s
...OR a Delco, also with internal VReg of similar output rating, mounted on a bracket which I can supply. Choice of Alt is a function of availability and serviceability in your area...for Portugal, I would expect you to prefer the Bosch.

LS; "cope with a bigger battery" is not a parameter of concern...Batteries are not sized by the Alt output, they are sized by Starting requirements and Reserve Rating, and for a standard (no special requirements like arctic or min weight) application, a 60A output Alt has gobs of extra output beyond what the vehicle uses to recharge a 60AHr Bat after Starting! ...and there is no issue with Positive chassis on vintage Volvos (thankfully!)...even the 6V vehicles had a Neg chassis, so wiring is not affected.

Cheers

[Laird Scooby]

LS; "cope with a bigger battery" is not a parameter of concern...Batteries are not sized by the Alt output, they are sized by Starting requirements and Reserve Rating, and for a standard (no special requirements like arctic or min weight) application, a 60A output Alt has gobs of extra output beyond what the vehicle uses to recharge a 60AHr Bat after Starting! ...and there is no issue with Positive chassis on vintage Volvos (thankfully!)...even the 6V vehicles had a Neg chassis, so wiring is not affected.

Cheers

Strangely enough Ron i know all that, having a Diploma in Automotive Electrical Systems and degree-equivalent in Electrical & Electronic Engineering.

Once up and running with no extra load (eg lights, heater etc) the current needs of the car will be relatively small, <10A so a 22A output dynamo will be ok. However, start adding lights, heater, possibly wipers etc to the mix and it won't. A 35A alternator won't fare much better and if a 60A/h battery is calling for 30A to recharge it and the car needs 10A, a 35A alternator will fall short - in other words isn't able to cope with a bigger battery.

The op (Arcturus) informed me earlier in the thread the car was +ve earth, given most Volvo alternators have insulated brackets through the mounting bushes, it should be possible to add a later Volvo alternator to a +ve earth car but care must be taken. Using an alternator with an external rectifier and regulator would be a way round it but again, care must be taken to ensure it is wired correctly.

As for the battery suggestion of about 43A/H, that is simple Ohms Law - 6V @85A is 510W as stated in the first line of my post - the rest is there. If it's a 1600cc car (which i think was mentioned - B16 - somewhere, a 45A/h battery will be more than sufficient to start it, especially in warmer climes like Portugal.

I'm surprised you don't already know all this, i've seen many of your posts and you're very knowledgeable.

[simonvolvo]

6V x 85A = 510W

510W / 12V = 42.5A

I'd suggest a 45A/h battery or slightly above, anything up to 60A/h would be fine but make sure your dynamo/alternator has a decent output in A to cope with a bigger battery.

+1.

Except, if you want to be really pedantic, the unit you should use for expressing battery capacity is Amp-hr, Ah, or the like (amps times hour, not amps per hour).

A 12v battery having the same capacity (i.e. work-performing storage) as a 6v battery need have only half the Amp-hr rating. My 12v Amazon runs on a 53 Amp-hr battery without any problems (although the handbook - for the B20 - specifies 60 Amp-hr).

[Laird Scooby]

+1.

Except, if you want to be really pedantic, the unit you should use for expressing battery capacity is Amp-hr, Ah, or the like (amps times hour, not amps per hour).


It works both ways round, a 60AH battery can deliver 10A for 6 hrs before it gets to a certain point (which i have to confess i can't remember just now but should, in theory, be enough to still start the car from cold) or 6A for 10hrs so in this particular case, multiplication or division is commutative in as much as both would apply to the ultimate outcome. :thumbs_up:

[Ron Kwas]

Simon, LS;

I am electrically qualified, so I'll be happy to discuss the finer points of the automotive elec sys, and product of Amps and Hours under us...my intent was to make it clear to op that Battery size is not specified as a function of Alt output rating, which the phrase "cope with a bigger battery" suggests.

Cheers

[Laird Scooby]

I thought you might be Ron but i've seen too many people fit an alternator in the belief that it will cope with anything to older vehicles and a huge battery and then discover to their horror that because their journeys are mainly low speed and short that the alternator isn't charging the battery. With a bigger battery (in terms of AH or A/h depending how you want to view it), this problem is exacerbated. A bit like when people are sold "Calcium Technology" batteries for cars that were only ever intended to use the standar lead-acid battery with lead-antimony on the plates to inhibit sulphation and not silver-calcium which requires a higher charging voltage to commence charging.

It's also plain to see the OP is doing this on a budget and there's nothing wrong with that but a larger battery is going to cost disproportionately more than a battery that will still be sufficient to power all he needs.

You see, when i said what i said, i wasn't just taking the technical side of things into account but also what i'd gleaned not only from this thread but from the OP himself and found the easiest words that would convey the idea to someone who expressed confusion as to the best place to fit a series resistor between two points. In other words, not electrically minded.

I'm sure i'd not doing him a disservice with those comments and apologies if so, however that's the opinion i had formed and did my best to accommodate without being patronising but giving the basic information in a form most people can accept and understand, even if there's a little "poetic licence" in the phrasology of it. :thumbs_up:

[arcturus]

FYI I still run dynamo, not alternator.That might come later :)

[Underdrive]

You beat me to it L.S. I saw your point about using too large a battery if infrequent short journeys are common, Lead acid battery life and efficiency are optimum when kept fully charged. The physical restrictions in the engine bay will probably limit choice anyway though.

[arcturus]

I always keep my batteries connected up to c tech trickle charger when not in use

[Laird Scooby]

I always keep my batteries connected up to c tech trickle charger when not in use

There are pros and cons to that idea, does your C-Tek charger have desulphation circuitry built in?

[arcturus]

There are pros and cons to that idea, does your C-Tek charger have desulphation circuitry built in?

Yes it does

[Laird Scooby]

Yes it does

That's not so bad then.

[arcturus]

All up and running.Now what is the position re' fuses ? Currently horn, heater and wipers 25.amp. 8.amp the rest. BTW still have 6volt horn running on 12V, have a 12V will possibly change later

[arcturus]

Ron, re' fuel gauge.I tried it with resister but probably didn't get it right. No fuel gauge or oil / charge lights. Removed resister and every thing works fine, even fuel gauge seems to be no problem.Can't guarantee it's veracity at this moment but never really could.

[arcturus]

Hi again,I need to convert blower fan to run with 12v. Which resistor should I use?

[Laird Scooby]

Hi again,I need to convert blower fan to run with 12v. Which resistor should I use?

Any idea what current it pulls at 6V and full speed?

[arcturus]

No info on that.I thought that some one might know that's why I posted photo of part number. My google search came to nothing.

[Ron Kwas]

Arcturus;

Simplest is to measure the current at 12V, then run the calculations at (https://www.sw-em.com/Vintage_Volvo_6V_to12V_conversion.htm#Dropping_Res istors) for the R value, and use that value.

Bill M. also reports there he used a 0.6Ohm DR when he did his conversion.

Cheers

[Laird Scooby]

No info on that.I thought that some one might know that's why I posted photo of part number. My google search came to nothing.

Have you got an accurate ammeter at all? I don't mean the one in a multimeter, usually the range on them is too low.

If not there are other ways and means of working out the current, i just wanted the easy route first! ;) :D

[arcturus]

Found this from Ron
nother more realistic example (I am told, that the single speed, PV444 6V wiper motor draws 5 Amps).

...more Kung-Fu:

Resistance = R = V / I = 6 / 5 = 1.2 Ω (Ohms)

Power = P = V X I = 6 X 5 = 30 Watts (a significant amount of heat!)
Just need to source a suitable resistor. Can you advise?

[Laird Scooby]

A 1.2 Ohm 50W (you always want the wattage to exceed the expected power by some margin) or 5x 6 Ohm 10W resistors in parallel. or 10 x 12 Ohm 5W resistors in parallel.

The neatest and as far as i can see, most cost effective way is this :

https://www.ebay.co.uk/itm/50W-0-1-8-2-Ohm-5-Aluminum-Housing-Resistor-Chassis-Mounted-Wirewound-Resistors/183758297337

Select 1.2 Ohms from the drop-down and take CV-19 precautions for example spraying it with IsoPropyl Alcohol before using it.

[arcturus]

thanks,a big help. I'm totally useless with electrics and also number dyslexic. More than three digits and my brain turns to mush.
Will order two and connect in parallel to keep heat down,OK?

[Laird Scooby]

thanks,a big help. I'm totally useless with electrics and also number dyslexic. More than three digits and my brain turns to mush.
Will order two and connect in parallel to keep heat down,OK?

No, just one. Putting two in parallel will give you 0.6 Ohms. At 6A, that's only a 3.6V drop so assuming 14.4V charging voltage, that's 10.8V across the heater fan motor. That will make the motor very hot (so may improve the heating! :tounge_smile: ) but in time will burn it out.

If you really want to put two in parallel, get 2.4 Ohms as in parallel, it'll give you 1.2 Ohms.

The formula for equivalent resistance of resistors in parallel is (R1 x R2) / (R1 + R2).

For example, two 100 Ohm resistors in parallel (100 x 100) / (100 +100) = 10000 / 200 = 100/2 = 50 Ohms.

Funny things can happen when multiplying decimal point values so if you said 24 x 24 / 24 + 24 = 576/48 = 12 and then replace the decimal point you "lost" for convenience, it's 1.2 Ohms again.

[arcturus]

Thank's.head gone into tail spin:)

[arcturus]

What a b*****d,they wont ship to Portugal!

[Laird Scooby]

What a b*****d,they wont ship to Portugal!

Have you any relatives/friends in the UK that would be willing to receive said resistor and forward it to you? :thinking:

[arcturus]

Will cast around.See if any one is locked down and still able to go to post office.

[Laird Scooby]

Will cast around.See if any one is locked down and still able to go to post office.

I know where i live the PO is shut, it's a sub-PO so independent from Royal Mail, not sure if similar will be reflected across other POs across the country. I know the posties are still working so presumably still collecting.