Why doesn't the engine turn backwards if you convert to 12 V neg ground.

[Deleted User]
[Deleted User]
edited November -1 in HUDSON
I have seen notes that say the starter does not have to be modified. If you switch the direction of current, why does the starter still turn the engine in the correct direction?

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  • bobbydamit
    bobbydamit Expert Adviser
    For "starters", please excuse the PUN, hitting that fly wheel with a 6 volt starter, powered by 12volts, is not a good idea. It is hard on the starter, the gear and especially the ring gear. Next, the starter does need to be changed because it is two copper windings, an armature and a field. The direction of turn is set up by these two and if you reverse one, the other is reversed as well and the starter turns the same. A caution for the starter is not to turn it over too long, as it will get hot and burn up. Last is the quick fix I use for dim lights and slow starts. I just go to a farm implement store and buy a 8 volt tractor battery. it drops in and no adjustments are needed. WAA LAA! Brighter lights and not conversions. Plus the Generator will keep it up or you can have a supply house get you a 8 volt regulator or an adjustable one. I have never found the need.
  • Park_W
    Park_W Senior Contributor
    As a supplement to the above, let's use a different way of explaining why reversing the polarity doesn't cause the starter to change directions: The key is the polarity relationship between the field and the armature. To reverse the direction, you have to change polarity for one and not the other. When you just change the battery polarity, the current flow through both the armature and the field windings is reversed, so their relative polarity remains the same, and the direction is unchanged. This is true for any motor except one with a permanent magnet for either the armature or the field. There, you can't readily change the polarity of the permanent magnet, so if you swap external connections or the polarity of the power supplied, the motor WILL change directions.
  • bobbydamit
    bobbydamit Expert Adviser
    Such is very true. Now don't anyone let these marble mouth explanations get ya confused with the AC motor with brushes, like the electric drill. That is a whole different story. Thanks for the simpler explanation Park. He is usually better at explaining these things. :p

    But hey folks, don't worry about the direction, just watch the teeth on the ring gear and the starter drive, plus long cranks if the car developes a starting problem. The starter will overheat on 12 twice as fast as 6. Get it wound for 12vdc, is the cats pajammies. :cool:
  • Unknown
    Unknown
    I installed an 8 volt battery in my 54 wasp this past year and I am impressed with it. I took the car down to our local shop who specialize in motors and all things electric and they adjusted my voltage regulator to a higher voltage probably 9 to keep the battery charged. It sure works good tho and no problems with changing bulbs, starter windings or anything. The starter turns over faster and the car starts better and bulbs are all brighter. A nice inexpensive improvement on the car.
  • PAULARGETYPE
    PAULARGETYPE Senior Contributor
    Lets Get To The Real Problemif You Need 12 Volts To Start Your Car You Have A Wiring Problem Or A Ground Problem With Good Wires And A Good Ground
  • Park_W
    Park_W Senior Contributor
    Paul is absolutely right. There are some legitimate reasons for going with 12v, such as ease of finding headlight and other bulbs when "on the road," brighter lights, ability to handle an A/C unit, etc. But these cars spin over and start just fine on 6v.
  • bobbydamit
    bobbydamit Expert Adviser
    Jimalberta wrote:
    I installed an 8 volt battery in my 54 wasp this past year and I am impressed with it. I took the car down to our local shop who specialize in motors and all things electric and they adjusted my voltage regulator to a higher voltage probably 9 to keep the battery charged. It sure works good tho and no problems with changing bulbs, starter windings or anything. The starter turns over faster and the car starts better and bulbs are all brighter. A nice inexpensive improvement on the car.



    Way to go James. I just knew there were other converts out there with happy tales to tell about this easy change. Now Add a 12 volt battery in the trunk with the solar charger on the rear deck and run all the AC or stereos you want, and let the sun be your power source. See earlier post of mine on this. 8/Volts is a great way to go!!!! And so much easier on our precious ring gears. :D
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