car starter ???

Discussion in 'General Electronics Chat' started by Mathematics!, Sep 26, 2009.

  1. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
    Ok , I am trying to figure out how a car engine turns on.

    Back in 1910s the cars didn't have batteries and you had to crank the engine to start it.

    Now we have batteries to do the work for us. But how exactly does the battery start the engine ,...etc?

    Is their away to rig something up if your starter dies but your battery is good to get the car started.

    I am just unsure how the starter starts the engine it looks like their is a soleinod on it but I cann't see how this device starts the engine.

    Does it go battery -- starter ---engine or is their some in between stage to start the car???

    So if a car doesn't start and their is nothing wrong with the engine then it must be the battery or the starter as the problem correct???

    But I don't see how the starter does the job of the crack in the 1910 cars?

    Thanks for any help. Sorry about all these question.
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Last edited: Sep 26, 2009
  3. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
    Ok thanks,

    How is the electric circuits rigged in a car?

    Like I know houses rig everything in parrell and use AC.

    However in a car's the 12 volt DC battery + goes to the starter and the - of the battery is hooked to the car body itself. But I am wondering what the circuit looks like in between. Is their more then one circuit or is it just one circuit hooked in parrellel withever thing or many circuits hooked in parrell.

    Just confused because in a house we have the main lines (120 2 + neutral ) lines coming in from the power lines. And from their (breaker box) we create as many different seperate circuits and hook everything on a circuit in parrell.

    But for a car 12 volt battery I don't know how it would work?

    Question 2
    If the battery of the car is ok then if the car engine doesn't turn over/start is the only problem it could be is a bad starter? ( <--provided the engine is not damage in anyway and fully functional)
    Or is their something other then the starter that could be the cause.
    Last edited: Sep 26, 2009
  4. SgtWookie


    Jul 17, 2007
    Actually, some did! When I was a kid, one of my buddies' fathers had a 1914 Premier automobile; a huge 4-door thing with a drop top. It was quite advanced for it's day; it had a 6-cylinder aluminum block engine, electric starter motor, electric shift, electric lights, and a Klaxon "ahhhOOOgah" electric horn.

    There was also an emergency hand crank in case the battery was dead. There was also an emergency manual shift lever in case the electric shift was out.
    There were no syncromesh transmissions in those days. To change gears, there was a Cutler-Hammer push-button switch box mounted on the steering column with the buttons labeled 1, 2, 3, N, R. You would push a button, and then push the clutch pedal to the floor which contacted a hidden switch. There was a loud crashing clunk as the solenoids in the transmission jammed into the selected gear, and you released the clutch to re-connect the engine to the transmission.

    High current, up to hundreds of Amperes flowing through a motor with high torque to spin the engine fast enough to "catch".

    With a manual transmission, push-starting in 2nd gear or parking on a hill has been popular for many years. With an automatic transmission, you're out of luck; the engine has to be running for the hydraulic pump to generate pressure to engage the clutch plates.

    Starter designs vary somewhat between manufacturers, but all perform similarly.

    Some starters use a solenoid attached to the starter; it causes the small gear teeth of the starter motor to slide towards the flywheel ring gear. Once the solenoid is fully extended and the gear teeth engaged with the flywheel, very heavy-duty electrical contacts are closed that supplies high current to the starter motor itself.

    Some designs use the motor's magnetic field to pull a large chunk of metal in to the body of the motor. The chunk of metal is hinged at one end, and drives the gear teeth into the flywheel via a fork.

    Yet another type uses an Acme-type screw thread design to sling the gear into the flywheel ring gear as the motor starts turning.

    There is usually a heavy-duty relay or solenoid somewhere in the system.

    Older Fords used a starter relay mounted on the inside of the fender, near the battery. Many GM cars used the solenoid/relay mounted on the starter itself.

    There can be a number of things wrong.
    Loose battery cables, broken battery terminal, corroded battery terminals, missing ground strap from the engine to the body, bad ignition switch, bad starter solenoid, the list goes on.

    Back in those early days, most auto engines had four or fewer cylinders, fairly low displacement, and they were practically all long-stroke low compression. It didn't take a lot of effort to get them going.

    One exception to this was the Oldsmobile Limited, made in around the 1911 to 1915 time frame. Very few of these enormous automobiles were made, and only perhaps five survive in restored condition, two of which I got to see a couple of years ago. They were equipped with huge 60hp 707 cubic inch (11.6 Liter) straight six engines, that were capable of propelling these juggernauts along at over 60 MPH.
  5. bountyhunter

    Well-Known Member

    Sep 7, 2009
    The starter is a very powerful DC motor. The battery is specifically chsen to be able to provide massive cranking Amps to it (like 600A or more). There is a short, thick cable from the battery to the starter with a relay to power the starter. No magic, just brute force.
  6. kkazem

    Active Member

    Jul 23, 2009
    Hi Mathematics!,
    The electrical system and starter in modern cars are really quite simple. When the key is turned from off to on, it supplies battery power to the ignition system (but no sparks yet), if you continue to turn the key clockwise to the start position, the starter motor gets connected to the 12V battery thru a high-current connection called a contactor, which is solenoid based. The starter turns the engine at an rpm suitable to start the car, but slow compared to even normal idle speeds. But the car wouldn't start unless the ignition was energized so as to create the sparks at precisely the right time for each cylinder. In most modern cars, lets say a small stick shift car, one cannot start the car without at least some battery power to run the ignition. Although the amount of battery power needed for the ignition is only a small fraction of that needed to turn the starter motor. If the battery was removed or extremely dead (less then 6 to 9 volts), one cannot hope to start the car by pushing it then popping the clutch in 2nd gear at about 3-5 mph. That works great if you have some battery power but not without a battery. By the way, electrical power is needed to keep the engine running after it starts. If the alternator (or generator in very old cars) is not working, the engine will only run until the battery gets depleted to the point that it cannot supply the ignition system with enough power for adequate spark. Additionally, many newer cars (actually, most) use fuel injection instead of a carborator and that usually requires more battery power than the ignition system.
    In the case of very old cars and modern small aircraft, the battery is not needed to keep the engine running as the ignition spark is created by a device called a magneto, sort of a small generator that runs on the rotation of the engine. In airplanes, there are always two per engine in case one fails. So, in summary, if your car battery dies from a bad alternator and you have a stick, you may be able to get the engine started, but it won't run long, especially at night with the headlights on. Electrically, the general flow is battery to ignition switch & to the contactor-->starter. The ignition switch has 4 basic positions. Accessory, which well ignore for now. Off position where you can pull the key out, on, and start. And of course start is spring loaded to return to on after the key is let go after starting. The on and start positions supply power to the ignition system and fuel injection system (in most modern cars). In the start position, the switch trips the solenoid in the contactor, enabling the high-current connection from the battery to the starter, which can be hundreds of amps. After the key is let go, it returns to the on position where it also supplies a small current to the alternator field coil which is simply an electromagnet. The spinning of the alternator creates a 3-phase AC output, which is full-wave rectified for a DC output to the battery for charging and other loads like fuel injectors, lights, window motors, stereos, etc. The full-wave rectified output is controlled by a voltage regulator circuit that's usually part of the diode rectification bridge. The DC output voltage needs to be regulated to avoid damaging the battery thru overcharging. This is easily done by measuring the DC output voltage to the battery and adjusting the amount of current in the field winding to obtain more or less DC output voltage/current as conditions change. The regulator will not allow more than about 14 VDC in order to get long life out of the battery. Well, that's about it. Please feel free to contact me with any questions about it.

    Kamran Kazem
  7. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
    Ok, but is the radio , wipers ,all the car electronics ...etc is it all on one circuit hooked in parrell ?
    Or are their many circuits. If their are many circuits I don't see where all the different circuits are hooked to the + on the battery?
    I am assuming since the - of the battery is hooked on to the car body all they have to do for the - part of each circuit's is hook it some where on the body of the car. But They would still have to hook all the circuits up to the + on the battery I don't see it?

    unless they run one wire from the + to some type of breaker/fuse box
    (like a house has then have all the circuits off that)

    Curious to know how the circuit's are rigged in a car. Are they ever in series?

    Question 2 back in one of you post you had mentioned about
    Is their away to use this as your own personal generator for electricity?
    Without having to by a $1000 plus generator at a store.

    Also since the alternator creates AC their must be a brigde rectifer and then a reglator after it to smooth it to a smooth DC. Either way if you hook wire before the rectifer I should beable to use it for a 60 Hz AC source. Wondering what exactly the rms voltage will be assuming it gets smooth back to 12 volt DC to resupply the battery. (so probably rms 12volts)

    Thanks for any clarity.
  8. SgtWookie


    Jul 17, 2007
    There are a few main circuits, and many parallel circuits. Most of them go through one or more fuse panels.

    Yes, many circuits do use the body of the vehicle as a ground.

    Yes, like that. In the "old days", there was just a single fuse box under the dashboard somewhere. Nowadays, vehicles with lots of electronics may have fuse/breaker panels under the hood, in the kick panels by the doors, under the dashboard, all over the place.

    Just inside specific boxes, like the radio box, cruise control box, etc.

    It wouldn't really be practical to use an automotive alternator for a 60Hz source. It has to spin at a fairly high RPM before it produces useful output, and that would be far beyond 60Hz; well into the kHz range.

    You can buy commercially available power inverters, which can be powered by 12v in, and produce 120v out at modest wattage. However, the outputs of such devices are generally not truly sine-waves; only approximations, and the power output is generally limited to under 1kW. Generating higher power levels would mean very high currents at low voltages.