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Battery cables are good. I have the LN grounded via the case ground on the back of the alternator which runs to the ground post on the drivers side battery. I also have a secondary ground which runs from one of the alternator mounting bolts and runs down to the engine ground on the drivers side.
If I understand you correctly, you have a ground cable going from the alternator mounting bolt, thus electrically connecting that part of the engine to the to the grounding point at the base of the block? Consequently connecting to the DS battery negative cable and connecting to the DS battery? What have you got grounding the frame of the truck to both the alternator case and the batteries?
@FordTruckNoob had some strange readings and observations with his LN alternator as well.
I will let him provide the details in an effort to keep them accurate.
Oops, Sous and I were typing at the same time. My response above was started before Sous posted.
My issues were due to old battery cables. I replaced my battery cables with CE Auto Electric cables and also added their charging system upgrade. That upgrade adds a monster ground cable going from the alternator’s case to the truck’s frame and also to the DS battery negative terminal. I also lubricated the contacts of the plug on the back of the alternator with conductive (not dielectric, conductive) grease. My problems went away after that. I had seen up to 15.1 volts before cable replacement.
If I understand you correctly, you have a ground cable going from the alternator mounting bolt, thus electrically connecting that part of the engine to the to the grounding point at the base of the block? Consequently connecting to the DS battery negative cable and connecting to the DS battery? What have you got grounding the frame of the truck to both the alternator case and the batteries?
I have two grounds coming off the alternator. One of the grounds comes off the back of the alternator and runs to the driver side battery ground terminal. The other ground is tied into one of the alternators mounting bolts and runs down to the factory engine ground on the driver side. I have NO grounds coming off the alternator and going to the frame. The ONLY frame mounted grounding point I have is the one that ties the passenger side of the engine block to the passenger side frame.
I have two grounds coming off the alternator. One of the grounds comes off the back of the alternator and runs to the driver side battery ground terminal. The other ground is tied into one of the alternators mounting bolts and runs down to the factory engine ground on the driver side. I have NO grounds coming off the alternator and going to the frame. The ONLY frame mounted grounding point I have is the one that ties the passenger side of the engine block to the passenger side frame.
All battery cables are new.
Try adding/relocating the heaviest ground cable you can wrestle from the back of the alternator’s case to the frame, then continuing on to the DS battery negative terminal.
Try adding/relocating the heaviest ground cable you can wrestle from the back of the alternator’s case to the frame, then continuing on to the DS battery negative terminal.
When you say "continuing on to the DS battery negative terminal" what exactly do you mean?
Logically speaking, I cannot see a reason why it would help. There are many metal-to-metal points of contact throughout the vehicle between all the major assemblies that should provide more than enough paths for electricity to flow. I followed that logic with all my attempts to resolve electrical issues with the truck with limited success. It was only when I installed that upgrade from CE Auto Electric where they added the monster ground cable that my problems went away completely. I wish I could explain why. I don’t think I have the patience or instrumentation to investigate. I suspect Hobbits are involved.
Originally Posted by F0rdc0wb0y
When you say "continuing on to the DS battery negative terminal" what exactly do you mean?
Like this:
One of those cables goes to the alternator’s case. The other goes to the DS battery -ve terminal.
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