Another Charging System Question for the Electrical Gurus

[provoflyfisher]

Hello,

I need some serious electrical help. I have searched prior posts and tried most things, but still need some advice.

The good - 1971 all stock bronco with new voltage regulator, battery, alternator, battery cables, starter, solenoid, ignition switch and clean grounds from battery to engine block, block to frame, and block to fender. Bronco was running fine then it sat for a few weeks while I got around to repacking the front wheel bearing. Started right up after sitting for this time and ran for 4 or 5 days perfectly.


The bad - Tried to start it up in the morning and a slow turn over, sounding like a dying/dead battery (no clicking just would not fire up after 2-3 seconds). Put the battery on the charger overnight and the same result. Put in another battery and voltage regulator and same thing. Checked voltage on batteries 12.5V, checked VR at FSAI with key off 12.5V (at A) no volts at F,S, or I. Key on still 12.5V at A, and 12.5 at S with 11V at F, 0V at I.
With key off or on battery cables are cool to the touch, but after I try to start it, I noticed both positive and negative cables heat up, as does the alternator case?

The ugly - I have had electrical issues off and on for 3 years, I thought it was fixed with the grounding network to various locations. Seems to work for a couple of months then back to square one.

I have checked for drains on the system with a light between the battery post and cable and there does not appear to be a drain. Noticed some rusting/corrosion on the VR at A terminal, small break on the inner fender may be letting in water when driving? I cleaned up the contacts and sealed this off to prevent future water coming in contact with the VR and harness.

I have not tried to jump the bronco from another car, but could try?

Any help will be greatly appreciated.

Thanks,
Burt

 

[Viperwolf1]

The voltages on the regulator are good. Cables heat up when passing a lot of current through a resistance. It may mean you have high resistance there or it may mean you were cranking it too long. 12.6V is not a full charge on a battery. I'd have the alternator checked.

 

[Steve83]

Where exactly did the cables & alt get hot? Over the entire length of the cables, or near a connection? You mentioned clean grounds in all but 1 critical location: alt to block.



What's the voltage at the starter terminal during cranking? Keep the black probe on a clean spot on the battery (-) post; NOT the clamp around the post.

 

[provoflyfisher]

Thanks for the information Steve and Viper.

The battery cables start warming up along the the first 12 inches from the battery and this is after a 3 second turn over and no longer. It seemed far too warm for such a short crank. It does not warm up if key is turned on, only after cranking. I also noticed the alternator (back of the case away from pulley) was warm after a 3 second crank?

I have not checked voltage at the starter terminal (can I ground on frame or block, my probe will not get me back to neg post?), I will do that next and also check that my ground from alternator to block is good and place a little electric grease at the interface. If that does not work I will have the parts store test the new battery and alternator.

Thanks for your help.
Burt

 

[provoflyfisher]

Checked volts at starter terminal and only 7V when turning the engine over. Same 7V at starter side of solenoid. Positive cable was too hot to touch on metal at both ends? Tried to jump start, but no different then without jump, slow turn over then nothing. I assume this would take the alternator out of the equation? Possibly starter solenoid or starter?

Thanks for your help.
Burt

 

[Steve83]

The main positive cable (the hot one) is the problem. Remove it & inspect its ends carefully. Clean the battery posts, AND the starter relay stud. Refer to these pics & captions:

.

 

[Viperwolf1]

Could be a shorted starter too. Short decreases resistance at the starter. Decreased resistance increases current. Increased current heats the cable/solenoid.

 

[provoflyfisher]

Fixed - bad starter

Thanks for all the advice Steve and Viper.

After inspecting all connections and replacing the negative cable and starter relay/solenoid with an old spare, I took the 3 month old starter in to be tested. It engaged fine but would not spin? Put a new one in and fired right up without any issues.

I am off and running until the next problem arises!!!

Burt