OUR VIDEOS GALLERY MEMBER SPONSORSHIP VENDOR SPONSORSHIP

User Tag List

Page 1 of 3 123 LastLast
Results 1 to 10 of 21

Thread: Alternator needs battery power to generate power?

  1. #1
    Legendary dom14's Avatar
    Join Date
    Dec 2011
    Location
    Somewhere inside Victoria, Australia :)
    Posts
    3,699
    Thanks
    2,124
    Thanked 575 Times in 461 Posts
    Mentioned
    38 Post(s)
    Tagged
    0 Thread(s)

    Alternator needs battery power to generate power?

    Hi Guys,

    I've been wondering(again).

    I'm onto a little garage project of combining an old mower motor with an alternator to make a simple generator.

    It is that i'm bit confused with the idea in the heading of this thread.

    1)Do I need to connect a 12V battery to the alternator exciter(or field wire/trigger wire) OR

    2)Can I simply join the field/trigger wire to the B+ and that should do the job?!!

    3)How do I use the sense wire? Do I need to join that to the B+ as well(when there's no load present)?

    Thanx in advance for any advice/tips/explanations.
    Attached Images Attached Images
    RB30, some 2-3 inch lift auxiliary LPG tanks
    Few more mods on the way
    http://www.worldwildlife.org/species/tiger
    https://www.panthera.org/
    Cheetah Outreach

  2. # ADS
    Circuit advertisement
    Join Date
    Always
    Location
    Advertising world
    Posts
    Many

     

  3. #2
    Expert
    Join Date
    May 2016
    Posts
    137
    Thanks
    10
    Thanked 62 Times in 45 Posts
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    A small battery to provide exciter power to get the field energised, after running and producing power then it could be run standalone but regulation will be shit. Use a battery on it (just a little mower battery is fine) and run the sense wire to the Battery + terminal. Ground or chassis to the - terminal.
    There is no legal cure for STUPID!

  4. The Following User Says Thank You to LostBenji For This Useful Post:

    dom14 (7th June 2016)

  5. #3
    Banned
    Join Date
    Apr 2011
    Location
    Greenbank QLD
    Posts
    3,387
    Thanks
    561
    Thanked 1,546 Times in 1,116 Posts
    Mentioned
    25 Post(s)
    Tagged
    1 Thread(s)
    Whats the generator going to be used for?

  6. The Following User Says Thank You to Yendor For This Useful Post:

    dom14 (7th June 2016)

  7. #4
    Legendary dom14's Avatar
    Join Date
    Dec 2011
    Location
    Somewhere inside Victoria, Australia :)
    Posts
    3,699
    Thanks
    2,124
    Thanked 575 Times in 461 Posts
    Mentioned
    38 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by LostBenji View Post
    A small battery to provide exciter power to get the field energised, after running and producing power then it could be run standalone but regulation will be shit. Use a battery on it (just a little mower battery is fine) and run the sense wire to the Battery + terminal. Ground or chassis to the - terminal.
    Thanx mate. If I understood you correctly, without the battery, it won't be possible to excite the field coil, and
    battery is also necessary for the ongoing voltage regulation as well?

    It's not possible to use the alternator as generator(12V or so) without a battery?

    Thanx
    RB30, some 2-3 inch lift auxiliary LPG tanks
    Few more mods on the way
    http://www.worldwildlife.org/species/tiger
    https://www.panthera.org/
    Cheetah Outreach

  8. #5
    Legendary dom14's Avatar
    Join Date
    Dec 2011
    Location
    Somewhere inside Victoria, Australia :)
    Posts
    3,699
    Thanks
    2,124
    Thanked 575 Times in 461 Posts
    Mentioned
    38 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Yendor View Post
    Whats the generator going to be used for?
    I'm thinking to run 12V appliances or combined with an inverter to run mains appliances, and of course on rare occasions to charge a battery as well.

    I imagined it might do lot better than my measly little generator?
    RB30, some 2-3 inch lift auxiliary LPG tanks
    Few more mods on the way
    http://www.worldwildlife.org/species/tiger
    https://www.panthera.org/
    Cheetah Outreach

  9. #6
    Banned
    Join Date
    Apr 2011
    Location
    Greenbank QLD
    Posts
    3,387
    Thanks
    561
    Thanked 1,546 Times in 1,116 Posts
    Mentioned
    25 Post(s)
    Tagged
    1 Thread(s)
    If your going to run accessories you will need to fit a battery, so you might as well make it a decent size one.

    The alternator might self excite but you will need to find the sweet spot in the RPM. This could be a bit hit and miss so I would recommend connecting up the exciter/warning light circuit. You can just connect this to positive (no warning light) but I would use a warning light. If you do just connect it to positive it will still need to be via a switch or it will flatten the battery when the alternator is not running.

    Just connect the sense wire to the B+ terminal on the back of the alternator.

  10. The Following User Says Thank You to Yendor For This Useful Post:

    dom14 (7th June 2016)

  11. #7
    Patrol God mudnut's Avatar
    Join Date
    Aug 2012
    Location
    SW Vic.
    Posts
    7,822
    Thanks
    10,607
    Thanked 5,354 Times in 3,172 Posts
    Mentioned
    80 Post(s)
    Tagged
    1 Thread(s)
    An old style twelve volt generator will have more chance of "self excitation", but a battery would still be needed to give proper voltage regulation as well.
    My advice is: not to follow my advice.

  12. The Following User Says Thank You to mudnut For This Useful Post:

    dom14 (7th June 2016)

  13. #8
    Legendary dom14's Avatar
    Join Date
    Dec 2011
    Location
    Somewhere inside Victoria, Australia :)
    Posts
    3,699
    Thanks
    2,124
    Thanked 575 Times in 461 Posts
    Mentioned
    38 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Yendor View Post
    If your going to run accessories you will need to fit a battery, so you might as well make it a decent size one.

    The alternator might self excite but you will need to find the sweet spot in the RPM. This could be a bit hit and miss so I would recommend connecting up the exciter/warning light circuit. You can just connect this to positive (no warning light) but I would use a warning light. If you do just connect it to positive it will still need to be via a switch or it will flatten the battery when the alternator is not running.

    Just connect the sense wire to the B+ terminal on the back of the alternator.
    Thanx mate..but..

    Alternator stator winding need the field winding(magnet) to generate electricity out of the stator winding.
    Then without a battery to initially turn the field winding into a magnet it apparently won't work?
    But, once the stator winding started generating electricity, it can feedback to the field winding and feed each other?

    So, it it essential to have a battery connected to the field winding, at least for a fraction of a second to generate electricity out of the stator winding?

    Does it work in theory?! I mean like chicken or the egg first sort of situation(which obviously I don't have to understand, but would love to ).
    Is possible by wiring up an alternator to self excite by connecting the trigger wire to B+?!!
    If I understood you correctly above, it's possible, provided I work out the proper RPM spot for that by experimenting?

    I understand that without a battery, alternator B+ output voltage won't be smooth(battery function as a capacitor to smooth the alternator's pulsed DC output?).
    So, if I'm to use an inverter, it would be a good idea to make alternator's output is smooth by connecting a battery to B+?!!
    And that would also apply to many 12V appliances as well.

    The only issue with using a decent size battery in the unit is that it would make it heavy. But, of course, the battery doesn't need
    to be attached/fitted to the generator.
    RB30, some 2-3 inch lift auxiliary LPG tanks
    Few more mods on the way
    http://www.worldwildlife.org/species/tiger
    https://www.panthera.org/
    Cheetah Outreach

  14. #9
    Patrol God mudnut's Avatar
    Join Date
    Aug 2012
    Location
    SW Vic.
    Posts
    7,822
    Thanks
    10,607
    Thanked 5,354 Times in 3,172 Posts
    Mentioned
    80 Post(s)
    Tagged
    1 Thread(s)
    You could use a small pony alternator that uses permanent magnets to give an initial start up. I have tried running alternators on a bench test, but I had to flash start the field.
    My advice is: not to follow my advice.

  15. The Following User Says Thank You to mudnut For This Useful Post:

    dom14 (7th June 2016)

  16. #10
    Legendary dom14's Avatar
    Join Date
    Dec 2011
    Location
    Somewhere inside Victoria, Australia :)
    Posts
    3,699
    Thanks
    2,124
    Thanked 575 Times in 461 Posts
    Mentioned
    38 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by mudnut View Post
    An old style twelve volt generator will have more chance of "self excitation", but a battery would still be needed to give proper voltage regulation as well.
    Yes, I think you answered my question on the previous post by the above answer.

    It's pretty obvious I need a battery connected to make the generator a useful thing for 12V appliances or mains appliances via an inverter, as you explained.

    My physics head can't get around the process of "self excitation".

    If the stator winding can't generate electricity without the field winding's rotating magnet, where on earth does the stator winding
    generate the initial electricity to power up the field winding??!!

    I can't get my head around that!!!

    What comes first, chicken or the egg?
    RB30, some 2-3 inch lift auxiliary LPG tanks
    Few more mods on the way
    http://www.worldwildlife.org/species/tiger
    https://www.panthera.org/
    Cheetah Outreach

Page 1 of 3 123 LastLast

Posting Permissions

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