I need help on DC

Discussion in 'The Projects Forum' started by 1989mustang, Dec 21, 2012.

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  1. 1989mustang

    Thread Starter New Member

    Dec 20, 2012
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    Hi everyone I am new to this site and need some help. Im building a 1989 5.0 mustang and Im going crazy with some issues with some electric radiator fans and ac blower motor that draw a lot of amps in return takes my my voltage charging system (130 amp) down to 12 volts from 14 volts :confused:.Can any one help me with regulating the draw on the radiator fans and blower motor where I can maintain a constant 13 volt charge. I can not figure this out So far I have tried to use resistors and still no luck can someone help Please.:)
     
  2. fz1

    New Member

    Dec 20, 2012
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    I'm still learning about electronics, but 15 years in auto parts tells me that what you should be looking into is a higher output alternator. I had a local rebuilder who took those motorcraft alternators and built them to 150, even 175 amp outputs.
    Just a thought.
     
  3. t06afre

    AAC Fanatic!

    May 11, 2009
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    If these motors are aftermarket. You will probably need a generator with higher output.
     
  4. 1989mustang

    Thread Starter New Member

    Dec 20, 2012
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    I have had one built a high amp alternator and they never tested it on the low end (idle) and they put low amps out at idle and I end up with the same problem one 180 dollar mistake I have already made. I can not get my money back cause it works but it takes 1300 RPM to get full amps looks like I'm up the creek without a paddle.
     
  5. t06afre

    AAC Fanatic!

    May 11, 2009
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    Have you tried some Mustang forums. They should be better prepared for solving your question. By the way this site do not allow automotive modification questions. Your question is inside the site rules. But if you had asked a question on how to modify your alternator. The moderators would have closed the thread. Take a look here at rule #6 http://www.allaboutcircuits.com/l_tos.html
    But you will always be welcome to ask any question that are not restricted:)
     
  6. 1989mustang

    Thread Starter New Member

    Dec 20, 2012
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    I understand but I'm not trying to modify anything but only see if anyone knows how to slow down a heavy draw that my fans and blower have not mod a alternator this is about DC current. I have checked mustang forums and most deal with it or say I have a bad ground I figured this site could give me a idea on the electronic side. Though this site does not allow car questions is crazy cause cars have more electronics now more than ever. Just my opinion don't want to offend anyone.
     
  7. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Did you rewire the car? What gauge wire is supplying the motors? Did you paint the frame or repaint the under hood area?

    Most car electric motor problems are from either to small a supply wire(to much voltage drop to the motor) or a grounding problem. I'd bet on a ground issue. Guys doing a build paint and some times even switch from a steel bolt in the ground strap to a stainless bolt. The paint and stainless bolt both increase the resistance from the battery negative to the chassis ground. They some times even leave off the small body and chassis ground straps, in an attempt to "clean up" the look of the wiring.
     
  8. 1989mustang

    Thread Starter New Member

    Dec 20, 2012
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    The only wireing that was done was a one gauge wire from alternator to battery and one gauge wire from batt to ground motor, yes the engine compartment was painted but all ground areas were taken down to bare metal before installation and original hardware was cleaned and reused. Both fans have a relay 60 amp and 2 12 gauge power wires going to both of the relays and the fans came with a 14 gauge going to them relay also has a 12 gauge ground wire.
     
  9. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    One more suggestion...
    On older cars, the radiator fins often get bent from rocks and other debris. That means the fan has to work harder to pull air though the radiator and, therefore, draw more current.

    Check to see if all the fins are straight and no leaves or other blockages exist.
     
  10. 1989mustang

    Thread Starter New Member

    Dec 20, 2012
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    These are new fans and new radiator when i check resistance one has 4.0 ohms and the other has 0.9 ohms and they pull hard the car is at a good 180 temp all the time fins are good so what can i use to slow them down?
     
  11. 1989mustang

    Thread Starter New Member

    Dec 20, 2012
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    Is there a a switch that I can use to gradually adjust the speed like a potentiometer?
     
  12. fz1

    New Member

    Dec 20, 2012
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    Unfortunately, the fans typically need to be running when the charge voltage is at it's lowest (idle). At highway speeds the fans don't need to be running at all, as air is forced through the radiator. Make sure you are using thermostatic switches set to the proper on/off temperatures, and consider making them kick on at different temperatures (fan 1 on at 195, fan 2 on at 210 for instance).

    I have a similar problem with my Yamaha: The charge voltage at idle is too low to maintain the battery state. It's a common problem with no aftermarket parts available to repair it. When I lived 3 miles from work, my battery would be too dead to start the bike after 10 days or so if I didn't take some long freeway rides to let the battery re-charge.

    Here are the mods I've made that have helped, if any of this gives you some ideas.
    1. Switched out as many lamps as I could and replaced them with LED's.
    2. Installed headlight cutout switch for daylight riding.
    3. Installed second battery in parallel to give me more of a "bumper" before I'm at a no-start level.

    Hope some of this helps.
     
    Last edited: Dec 21, 2012
  13. Wendy

    Moderator

    Mar 24, 2008
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    The owners of All About Circuits has elected not to host discussions of automotive electrical system modifications/enhancements due to safety concerns, the potential of legal ramifications and the possible circumvention of vehicle regulations at the state and federal level.

    This thread is against the AAC forum rules, Chapter 6, as seen here:

    This can be found in our Terms of Service (ToS)

    Automotive modifications of any kind are strictly forbidden. Therefore, this thread will be closed.

    Please try to understand the reasons behind this action, and feel free to browse and use the forums.

    You might find answers to your questions in one of these forums:

    http://forum.allaboutcircuits.com/showthread.php?t=54400

    Another good forum that shares many of the same membership is http://www.electro-tech-online.com/ . Good luck.
     
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