I recently boutght a 68 F100 and have noticed when I drive it for about 20 minutes and turn it off.
1. And then try to start again after 10 minutes --- difficult to start -- which can lead to draining the battery.
2. As I touch the battery cables they are very warm -- both cables.
I am getting ready to try and diagnose the problem.. battery? points system? regulator?
One thing no one has mentioned yet; cable size. What size are your battery cables. Too small of a cable will absolutely cause them to get hot even under normal operating conditions.
Also, both your battery positive and negative cables must be the same size. All of the current going out in the positive cable comes back to the battery in the negative cable. Too small of a cable on one side or the other will act as a series resistor to the entire circuit and can cause overheated cables exactly like you describe.
Personally I prefer nothing smaller than "00" battery cables for alternators of less than 100 amp output, which was typical for these trucks, excepting some Camper Specials and Contractor Specials, which probably were delivered with bigger alternators and associated wiring. Look for an amp output tag or stamp on your alternator. When in doubt about wire sizing, always go bigger.
This link http://www.powerstream.com/Wire_Size.htm will take you to a website that will allow you to use their calculator for selecting the proper size wiring for all of your electrical projects. Make sure you accurately enter all of the required information or the calculation will be wrong.
Also check what your actual operating voltage is at various RPM's at the battery posts with an accurate digtal voltmeter. If your voltage ever reads above 14.5 volts at any RPM I would consider testing your voltage regulator. The higher the voltage output is the greater the amount of current being pushed which will also cause the cables to get hot. If the voltage output tests under 14.5 volts at all RPM's and you can not troubleshoot any other causes of your hot cables then you may want to consider using bigger cables at the battery as well as a bigger cable from the alternator to the starter relay on the fender.
On an FE 2 awg is the largest you need unless you get a 175 amp alternator. Please read below.
The numbers in that site are whacky when compared the automotive wire manufactures, the construction and power electrical manufactures. There is no electrical designation for chassis wiring and power transmission wiring in the US or Europe. Wire current rating is based on insulation strength, wire diameter, resistance and number of wires in a bundle and if the bundle is enclosed or open. Not by what purpose the wire is being used.
2 awg wire is rated at 115 amps at 167c degrees. 2/0 or OO is rated at 175 amps at the same temperature. The 167 degrees F is the maximum temperature that wire can handle at that amperage more amperage and the wire must be used where it can run cooler.
I have this book mentioned below and it says the table mentioned is not to standards allowed by the NFPA. No one not electronic engineer or electrical engineers follow that book nor is it recommended for use as a study guide for electronic or electrical engineer tests. That alone should point out how off that table is compared to what is used to build wiring harnesses house and power lines.
Handbook of Electronic Tables and Formulas for American Wire Gauge. As you might guess, the rated ampacities are just a rule of thumb.
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