Voltage Regulators / Unregulated Voltage
  • Register
  • Help
Results 1 to 16 of 16
Like Tree7Likes
  • 4 Post By 1972Ren
  • 1 Post By bowie
  • 1 Post By JohnW
  • 1 Post By COL

Thread: Voltage Regulators / Unregulated Voltage

  1. #1
    1000+ Posts bowie's Avatar
    Join Date
    Aug 2002
    Location
    Sydney, Concord City, Sir.
    Posts
    3,395

    Default Voltage Regulators / Unregulated Voltage

    The dash has come out of the race car (early Renault 12 for the new people) for some cleaning and thinking, I note there is a substantial unregulated lead directly of the alternator headed into the cabin.

    In my excitement I forgot to pay attention, what in the cabin would require a unregulated ~V+ source? The key switch to the starter?

    Advertisement


    As the regulator is external, I would have though the cabin +V source would be from it.?

    Wait... the regulator is external, but so what. The +V source of the alternator "is regulated"!

    Right?

    Confusing as there is a +V source from the regulator that finds it's way into the cabin also. Why have both? Unless that's just for the battery warning / alt / charge light?

    Long story short, as long as I can assume the +V of the alternator is regulated, I can work with it. I just wanted to check that I shouldn't be taking the +V directly of the regulator.
    Last edited by bowie; 8th September 2019 at 09:24 PM.

    Works: 2003 YV Commodore (That is Cecil to you)
    Playing: R12, SuperPos, thinks It's a race car and Sunny the R12 Lego set.
    Previous: SuperGrumpy fuel spitting 504ti(ish), SuperComfortable 505 STI, SuperDoper carried my groceries Mi16, Choo Choo'd Volvo S40
    Wanted Will hoard 12/15/17 Junk.

    "More and more of less and less" - Marina Abramović

  2. #2
    1000+ Posts
    Join Date
    Jul 2001
    Location
    Perth, Western Australia
    Posts
    6,293

    Default

    Bowie, I seem to remember on my 12 the alternator had its field coils excited by the dashboard 'charge' lamp - could this be the reason for this wire? Although, I wouldn't have though it would need to be a 'substantial' wire.


    2003 PEUGEOT 206 GTi

  3. #3
    1000+ Posts robmac's Avatar
    Join Date
    Nov 2004
    Location
    Melbourne / Caulfield
    Posts
    19,094

    Default

    If you have found a "tree trunk" cable behind the dash. I suspect it is the supply to a high current load.

    I'd suspect the head light switch.

  4. #4
    Fellow Frogger!
    Join Date
    Feb 2018
    Location
    Australia
    Posts
    620

    Default

    Quote Originally Posted by bowie View Post
    Long story short, as long as I can assume the +V of the alternator is regulated, I can work with it. I just wanted to check that I shouldn't be taking the +V directly of the regulator.
    Yes, I believe that is right. Whether the voltage regulator is internal or external, either way it is keeping the + terminal on the alternator at a steady 13.8v. Normally there is a big, fat, power cable going to the dash, attached to one side of the ammeter.

  5. #5
    1000+ Posts robmac's Avatar
    Join Date
    Nov 2004
    Location
    Melbourne / Caulfield
    Posts
    19,094

    Default

    Normally there is a big, fat, power cable going to the dash, attached to one side of the ammeter.
    It's been a long time since I've been in an R12. I don't believe they have a ammeter. This would be typical of a fitted with an alternator by the manufacturer.

  6. #6
    COL
    COL is offline
    A110 COL's Avatar
    Join Date
    Mar 2002
    Location
    Van Diemen's Land
    Posts
    4,063

    Default

    Quote Originally Posted by robmac View Post
    It's been a long time since I've been in an R12. I don't believe they have a ammeter. This would be typical of a fitted with an alternator by the manufacturer.
    Renault R12's didn't come standard with an ammeter like Rob says above, the early cars with VDO gauges had a light and the later cars with Jaeger gauges had a volt meter.

    I have circuit diagrams for the cars with Jaeger instruments but not with VDO instruments.

    Let me know Dan if you would like a circuit diagram, I will scan and email it to you
    Regards Col

    1973 Renault R12 Station Wagon
    1976 Renault R12 Station Wagon
    2002 Renault Laguna V6
    1973 Alpine A110

    http://alpine-a110.weebly.com/

  7. #7
    1000+ Posts schlitzaugen's Avatar
    Join Date
    Nov 2010
    Location
    loneliness capital of the world
    Posts
    8,905

    Default

    A couple of general background points.

    A gauge needs regulated power otherwise it will be all over the place. Gauges (analog) are basically voltmeters/ammeters, i.e. a moving coil deflected against a permanent magnet field or viceversa.

    An unregulated +12V could be as Stuey said the alternator excitation through a bulb, but this one needn't be fat at all.

    Or it could power headlights or any other globe, because these don't care about regulation much. This should be fat, but it shouldn't come off the alternator output because you should be able to turn headlights on with the engine off.

    The ignition switch takes power from the battery to energise the starter, so it needs no regulation. But I don't see why this would need to go through the alternator either.

    I would suggest you check if this fat wire coming off the alternator comes off the output of the alternator or input (excitation). This should clarify some. Check where it's going as well and most if not all will be revealed.
    Last edited by schlitzaugen; 10th September 2019 at 08:06 PM.
    ACHTUNG ALLES LOOKENPEEPERS

    Das computermachine is nicht fur gefingerpoken und mittengrabben. Ist easy schnappen der springenwerk, blowenfusen und poppencorken mit spitssparken. Ist nicht fur gewerken bei das dummkopfen. Das rubbernecken sightseeren keepen hands in das pockets-relaxen und watch das blinkenlights.

  8. #8
    Fellow Frogger!
    Join Date
    Feb 2018
    Location
    Australia
    Posts
    620

    Default

    Sorry but it seems there is a bit of confusion here on some basic car electrics matters!

    All the charge lamp does, is light up when there is a difference between alternator output voltage, and battery voltage.
    It is installed in a wire which comes from the ignition switch, and goes to the alternator, to provide field current, before the car has started. That wire is small, as the current required to create the field is not much.
    After the car has started, field current is supplied from within the alternator.
    The bulb lights up when the ignition is On, and the car not running, because at that point, the alternator output is 0 and the battery is 13v or so.
    When you start the car, the alternator output and battery voltage are normally the same, so the light goes out.
    It is not necessary to have a bulb at all, but they are typically bypassed with a resistor which is high enough to not stop the bulb working as intended, but allows field current to pass if the bulb blows. Otherwise the alternator could never start itself in the first place.

    Noted that the car in question does not have an ammeter. Instead the fat wire is providing power for the headlights and all the other things which draw current.


    The regulator in an alternator is regulating the field current. It is NOT like a regulator you pick up in Jaycar, where you apply a somewhat varying voltage to it, and it outputs a dead steady fixed voltage. It senses alternator output voltage, and when it rises to ~14.5v it shuts off the field current. When the alternator voltage drops to ~13.5v, it turns it back on. It does that hundreds of times a second, to keep the alternator output voltage at the desired level.

    Obviously this will come as a surprise to some, but the output terminal of the alternator is live ALL THE TIME, including when the ignition switch is off. A typical arrangement, on classic cars anyway, is that the battery + goes to the starter, and another wire goes from the same post, to one side of the ammeter (yes, if there is one). The other side of the ammeter goes to fuse box, ignition switch, and alternator output. There is no difference between powering the headlights from the battery vs the alternator +.

    Lastly, the voltage regulator used to power some instruments has NOTHING to do with the VR in the alternator. It is a separate device used to create a reference voltage for instruments, and that is typically a few volts below nominal alternator output. The only one with which I have had personal experience used a 10v regulator for Smiths gauges.

    As for Bowie's question, then, the answer is that all power wires in the car are providing the same voltage; there is no different 'regulated 12v' vs 'unregulated 12v'. The external VR is ONLY to control the field current in the alternator and does not power anything else in the car.

    Thanks
    Andy.
    JohnW, Renault Rod, bowie and 1 others like this.

  9. #9
    Fellow Frogger!
    Join Date
    Dec 2010
    Location
    Melbourne
    Posts
    407

    Default

    Hi Bowie. That big wire will be live all the time as others have said. It runs in Parallel with the battery and is regulated. It should be a white or sort of cream color. It will junction with a thick yellow and (dependent on model possibly a red one too) going back into the main loom as well as a wire to the ignition switch. The yellow goes to the battery. These thick wires junction at a 5mm terminal on the headlight switch or if a very early car to a spade terminal block just behind the dash. That 5mm bolt (or spade junction) provides all the unfused circuits inside the car and there will junction to a couple of other “big wires”, one leading to the ignition switch to supply power to all the switches circuits. If you need a diagram I have them, also have a 3d model in the form of a few r12 looms in my lounge room and dining room at the momen.

  10. #10
    1000+ Posts bowie's Avatar
    Join Date
    Aug 2002
    Location
    Sydney, Concord City, Sir.
    Posts
    3,395

    Default

    Andy!

    Thank you for confirming that. Your description was very clear, it coupled with the Haynes left me with a "Ah Haa!" moment.

    Right, now with that out of the way, all this is of interest as I've removed the dash and front lights, blinkers / horn wiring loom from the front and might as well rewire the rest of the car.

    https://photos.app.goo.gl/hAbKCjprYoyBD49w7
    https://photos.app.goo.gl/3Pucvfjp7LeeKKax8
    https://photos.app.goo.gl/8pfu7vpBzUzm1YD9A

    Isn't that a glorious mess. Surprisingly, the loom is in pretty good condition. I thought French electrics where supposed to be sh1t. I might even re use some of the lengths.

    Note in the second image that crack that was to the left of the loud peddle isn't going away. I'm going to have to scratch that back and see what surprises are in store...

    But now I've got the confusion about external regulators out the way, I'll go about making up a brief fuse board / relay / junction box and wire up what I need, probably on some cool Group B style panel in the middle of the dash because blade fuses and switches are cool yes. The list isn't that great, and since I don't need it to function as a car, I can make some modifications.

    -Brake lights
    -ECU
    -Coil
    -O2 Sensor
    -Radiator Fan
    -Windscreen wipers
    -Starter Motor
    -Spare

    And I can probably combine a couple of those items into a single fuse. I note my 12 had but 2 fuses, one for all the lights, and one for windscreen wipers.

    Anyway Thanks Andy. I'm confident I can start to think about how to connect all this together via a nice kill switch.

    Cheers!
    1972Ren likes this.

    Works: 2003 YV Commodore (That is Cecil to you)
    Playing: R12, SuperPos, thinks It's a race car and Sunny the R12 Lego set.
    Previous: SuperGrumpy fuel spitting 504ti(ish), SuperComfortable 505 STI, SuperDoper carried my groceries Mi16, Choo Choo'd Volvo S40
    Wanted Will hoard 12/15/17 Junk.

    "More and more of less and less" - Marina Abramović

  11. #11
    1000+ Posts bowie's Avatar
    Join Date
    Aug 2002
    Location
    Sydney, Concord City, Sir.
    Posts
    3,395

    Default

    Angru / Col, A wiring diagram would be appreciated

    Works: 2003 YV Commodore (That is Cecil to you)
    Playing: R12, SuperPos, thinks It's a race car and Sunny the R12 Lego set.
    Previous: SuperGrumpy fuel spitting 504ti(ish), SuperComfortable 505 STI, SuperDoper carried my groceries Mi16, Choo Choo'd Volvo S40
    Wanted Will hoard 12/15/17 Junk.

    "More and more of less and less" - Marina Abramović

  12. #12
    Fellow Frogger!
    Join Date
    Dec 2010
    Location
    Melbourne
    Posts
    407

    Default

    Pm me your email and I’ll email one to you (have ‘71 diagram scanned into phone map if that helps can do it now).
    With that list of circuits I’d probably consider running a couple of fuses in the engine bay, they’d be coil(although you may not need a fuse for that), o2 sensor (if it needs power to heat it) and rad fan (yep, that should be fused).
    Could combine brake lights and wipers as you’ll want them unswitched. And combine interior fan with indicators, as they’re both switched with ign, as is demister switch if fitted and + supply to instrument panel.
    Then a sensible upgrade may be to run a fuse in the high beam circuit in the cabin just after the switch and a fuse in the low beam circuit after the switch, or could relay them in the engine bay and run fuses to the supply side of the relays in engine bay, and take the current out of the switch contacts, but that may be an overkill depending on what you’re using it for.
    What ECU you running? Probably a good idea to have a fuse for the fuel pump on it’s own and, if controlled by ecu, trigger the relay with that.. if not controlled by ECU make sure you get a tachometric relay to prevent fuel pump running on in event of engine stopping in accident situation.

  13. #13
    Fellow Frogger!
    Join Date
    Feb 2018
    Location
    Australia
    Posts
    620

    Default

    Re the tachometric relay, I second Angru's suggestion, and have fitted to a couple of cars into which I put an electric fuel pump.
    Just replaced one the other day, and bought it here


    https://www.justkampers.com.au/tacho...fuel-pump.html

  14. #14
    Too many posts! JohnW's Avatar
    Join Date
    Jul 2001
    Location
    Perth, WA, Australia
    Posts
    10,800

    Default

    Quote Originally Posted by bowie View Post
    Surprisingly, the loom is in pretty good condition. I thought French electrics where supposed to be sh1t. I might even re use some of the lengths.
    Dunno where this surprise comes from. I have never had a loom problem in 50 years and my 1950 4CV and 1964 R8 looms are just fine. My only grumbles have been cheap rocker switches with R12/16s but I don't recall a failure except for one wiper switch.

    Good you are getting on top of things.

    I'd back 1972Ren's explanation too - as I understand it, all that is "regulated" is the output voltage of the alternator when it is running, so it doesn't matter whether a wire comes from the battery or the alternator output terminal (or the big terminal on the starter) as they are directly connected to each other.

    Cheers
    1972Ren likes this.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    Citroën CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  15. #15
    COL
    COL is offline
    A110 COL's Avatar
    Join Date
    Mar 2002
    Location
    Van Diemen's Land
    Posts
    4,063

    Default

    Quote Originally Posted by JohnW View Post
    Dunno where this surprise comes from. I have never had a loom problem in 50 years and my 1950 4CV and 1964 R8 looms are just fine. My only grumbles have been cheap rocker switches with R12/16s but I don't recall a failure except for one wiper switch.

    Good you are getting on top of things.

    I'd back 1972Ren's explanation too - as I understand it, all that is "regulated" is the output voltage of the alternator when it is running, so it doesn't matter whether a wire comes from the battery or the alternator output terminal (or the big terminal on the starter) as they are directly connected to each other.

    Cheers
    The only rocker switch problem I have had in R12's is when the lubricant dries out and the switch becomes hard to operate, the simple fix it to dismantle the switch, clean out all the old dry lubricant and use something like Vaseline in place of the old lube and then re-assemble. Walla a switch that is as good as new.
    JohnW likes this.
    Regards Col

    1973 Renault R12 Station Wagon
    1976 Renault R12 Station Wagon
    2002 Renault Laguna V6
    1973 Alpine A110

    http://alpine-a110.weebly.com/

  16. #16
    1000+ Posts bowie's Avatar
    Join Date
    Aug 2002
    Location
    Sydney, Concord City, Sir.
    Posts
    3,395

    Default

    Just to draw some pictures to the source of the confusion.

    https://photos.app.goo.gl/LV7UhFb5cKQiNjbB9


    This is the red wire of the regulator, that is part of the key switch mechanism, that is fused along the inner drivers wing guard, before then appearing back into the cabins electrical system (after fuse). Assuming, to the power the switched block under the dash?

    Here you can see the plug in red, as it would connect with the ignition switch.

    https://photos.app.goo.gl/MVhEq4gSMCsVKmoMA

    I was supersized that the switch was connected to the regulator, I assumed (but didn't look and think about it to hard) that there would be a relay involved somewhere, and that the key switch would be connected to the thicker cream gauge wire that is spliced into the Battery / Alternator. I.e always 12v at the key switch.

    I suppose as you have to get a thick cable into the interior to power everything on the inside I thought they'd use that to switch but no. But having said that, this post on the regulator is always on 12v anyway?


    So on this plug we have;

    Red heading north = to the red output on the regulator (which will always be a constant 12v source with the battery connected right?)
    Grey heading north = Switch for the starter motor (assuming this is a switch to ground as it takes power and ground directly from the battery)
    Red heading west = to the fuse panel on the inner guard (removed under the ID tag) which is then, passed back into the cabin.


    With that in mind, can I remove the regulator output (that red wire) or should I work at ensuring it connects back into a 12v somewhere / directly onto the battery? I'm still a bit nervous around. I.e I understand it controls the alternators field generator by measuring the voltage, but can't explain what would happen if it wasn't able to pass current via it's 12v outlet.

    Cheers all,
    Dan

    Works: 2003 YV Commodore (That is Cecil to you)
    Playing: R12, SuperPos, thinks It's a race car and Sunny the R12 Lego set.
    Previous: SuperGrumpy fuel spitting 504ti(ish), SuperComfortable 505 STI, SuperDoper carried my groceries Mi16, Choo Choo'd Volvo S40
    Wanted Will hoard 12/15/17 Junk.

    "More and more of less and less" - Marina Abramović

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •