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My problem is obvious
I'm certain that a few of you will be saying this (and more). Electrical troubleshooting is not my strong point, I've set cars on fire before. I could show the Butcher of Bagdad a thing or two!!
My Cobra runs great, except the battery isn't charging. My reaction is: ground the voltage regulator. I've already done that. The battery accepts a charge from my benchtop charger just fine. For whatever reason, the car isn't recharging itself. Now the specifics: External regulator, no computer, duraspark ignition. How can I SAFELY diagnose this?%/ |
Check the voltage with the cat runniig. If its not over 13 or so volts, change he altanator.
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If that doesn't work try changing the alternator:3DSMILE:
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JT,
Were things working fine at one time and now it's broke? I'm tring to isolate a sudden hardware failure from a wiring problem. If it's a sudden failure, swap out the regulator first, and if that doesn't get it, then try another alternator. Gotta be one or the other. - Jim - |
It could be many things, the most likely are the regulator and alternator. You can remove these, take them to an auto parts store and have them checked for free.
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JT,
My experience with auto parts store trouble shooting is that they seldom know how to operate the tester, and usually don't have a clue as to how an alternater works. Please keep that in mind.... |
First: Make sure that the alt is grounded VERY well. Use a test light and check for power at the input terminal of the alternator. If power is there, hook a jumper wire between the 2 terminals on the voltage regulator marked B and F run the car and CAREFULLY check for power. If power is there when you charge the field terminal, you have a bad regulator. If no power there at all, a bad alternator. If you have power when you jump but not without the jumper, you have a break in the field wiring circuit. THIS PRESUMES THAT YOU ARE USING A FORD VOLTAGE REGULATOR AND THE OLD STYLE FORD ALTERNATOR! Any other questions, post and I will go thru more details with you. If you are running an idiot light, check to make sure its wiring is not broken as well.
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And......
If you do not want to do what Sharpe has offered (excellent instructions), I would go to a place that does only automotive electrical and have them test the alt and regulator, off the car.
**) **) **) David |
A simple test to see if the alt. is working is to place a screwdriver or any othe small steel rod next to the rear bearing of the unit. If it attracks( like a magnet would) the alternator is working.
Scott S |
Latest developments...
I don't know if the car was charging-I tend to doubt it. I installed the volt gauge tonight and the result is: 11.0 volts static, 11.0 volts with car running. Dead cell?
I tend to think the alternator isn't operating either because it isn't getting any voltage or it's not making any. (brilliant, huh?). I'll try some jumper wire work tomorrow, and a few additional ground wires-until then I need some sleep. Thanks to everyone for the input, I don't feel so lost at this point. JT |
1 Attachment(s)
JT,
I just had the same problem with my car (conincidently it's also an A&C). If my attachment doesn't work, send me an e-mail. I'll send you the drawings. -Steve wadesdad@hotmail.com P.S. I really like my A&C car, less than a week on the road. |
I have a setup the same as pictured in wadesdad's diagram on the right. I had to change regulators 2 or 3 times before I got one that would allow the alternator to charge at about 13.9 or 14 volts. I have an electric fan, electric water pump, MSD box, etc. My problem is an night when everything is running and I have my headlights also on, the voltage is only about 12 V or so (11V at idle). I had the alternator rebuilt using all the "high output" stuff and the shop said it was putting out 100+ amps at full RPM. I have never had to charge the battery and the car starts and runs just fine, I am just a bit concerned about the low voltage at night.
I am wondering if the wire from the alternator to the battery "+" may not be heavy enough to allow the required current to flow. Any ideas? What gauge should this wire be? I am also considering changing my electric fan which seems to draw a lot of current. |
Wayne, most feed wires are either 8 or 10 gage. No fan should pull enough to kill a good alternator. Most of the old style Ford alternators have been rebuilt to at least 63 amps, and that should run any Cobra effectively. Remember that this same alt runs the old Lincolns and all their electrical gadgets without breaking a sweat....
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Reply to Wayne:
I suspect you have your electric fan wired so it runs at all times when the ignition switch is on. At night, I'd doubt my fan would even come on, except at a long stoplight. The electric fan uses an amazing ammount of amperage. You may consider either a thermal or manually controlled switch to control the fan, particularly at night if your charging system is close to the edge. As they say-it's just my $0.02. Reply to Sharpe: I re-read your reply to me and I think I caught something I missed earlier regarding jumper diagnosis and a bad winding. Hmmmm, this confirms my suspicion that the alternator is the culprit. That is good news, since it is still under warranty and easy to test. 9:00 pm and still 75 degrees out. Cobra sits. Damn. :CRY: |
I just love a happy ending.
FYI to all: I rewired my ALT/VR as per Wadesdad's schematic (left side) and made 15V @ 2,000 RPM and 12.5 @ idle. SUCCESS!
Thank you to everyone. Your interest and support means alot to me, especially when I haven't got a clue. "We got a tankful of gas, a half a pack of cigarettes, it's nighttime, and we're wearing sunglasses". "Hit it!".:cool: :cool: |
ERA's Bob Putnam deserves all the credit. I was just sharing info. I gleaned from his expertise.
-wadesdad |
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