Hey there guys, I desperately need some help. This is kind of a long story so please bare with me.
Ok so about two weeks ago I get in to start my truck and there is a click and then nothing. And I mean nothing as in no electrical power to ANY of the components that usually will show life when the key is turned on. But I also noticed the was no dome light either. Basically the anti theft light and the power aux ports are the signs of life in the truck. I jump start the truck with another vehicle and I go to get my one year old battery checked. Battery good. So we think it's maybe the voltage regulator/alternator. So I replace it. Song with battery post connections. Problem appears to be solved because the truck fires right up with all electrical issues seemingly resolved. 3 or 4 days later it happens again. Some one days check the ground connections. So I go through all connections I can find them start I just start checking everything from battery to starter, battery to power distribution block, to ignition. All of it. Everything appears to be ok but I notice my ignition may be a little sloppy. So I start wiggling a few of the connections just to see if there is any change. Nothing. Now keep in mind I can still jump start the truck with another vehicle but it will not be push started in any way because it has zero electrical signal to anything ( even things that normally would when hey is turned on). So I jump the truck again and since I am still making my way home from Las Vegas I decided to just keep the truck running all day even through fuel fill ups and everything.
Several hours and several hundred miles later I have my girlfriend drive the last 100 miles or so before i am dead tired and the only issue we seen to be having is that when the air vent switch is turned on the whole vehicle would react as if we were tied to a tree or something and the rope pulled tight. I mean we'd be doing 40 and when we turned that switch on we'd instantly be knocked back to 30 or 35. It y so it seemed. She pulled off to the side of the road to stretch her legs and when she started to pull away again I noticed she was in some soft deep dirt that if not careful could cause a stall out. Well guess what... She stalled it out and when she did, everything and I mean everything shut down electrically. Including the anti theft and aux power this time. So when key is turned on the is nothing, no clicks no beeps, no cranking no lights no nothing. Battery shows 12.9 volts but still nothing. And now it will not accept a jump or push start in any way at all. I am so frustrated and confused by all this I literally want to just blow it up on the side of the road. But I love my truck and I NEED my truck for work on Tuesday and right now I'm screwed. Can someone please point me in the right direction. Thanks

 

The battery is only used to start the engine, and power the electrics of course when engine is off

Once started the Alternator powers everything, battery is off line
Alternators minimum voltage output is 13.5volts, battery highest voltage is 13.0volts
So when engine is running voltage flows TO the battery(keeping it charged up) nothing comes out of the battery

So key on engine off and no lights or starter motor means the battery is disconnected, period, no wondering or guessing, battery is disconnected from the vehicle
Nothing to do with alternator, its off if engine is not running

If you clamp jumper cables to the OUTSIDE of the battery cables on the battery, and you now have electrical power and can start the engine then the battery cables and their connections to the vehicle are OK
Issue is the INSIDE of the battery cables and their connection to the battery terminals, and can even be a bad battery, there are connections inside the battery to the outside terminals, and they have to be able to pass the same high amps as the outside battery cables

On a 2000 Ranger there should be a MEGA Fuse on the outside of the engine bay fuse box
One side of that fuse should have a Red wire from Battery Positive terminal, with key on engine off ALL electrical power from the battery to the whole vehicle passes thru that one red wire connection to the fuse box, needs to be clean and dry
And of course all the Negative battery terminal wires need clean connections to engine, body and frame

But all of the above connections would have to be GOOD.................if Jumper cables from another battery worked when hooked up to both the cables of current battery then battery is the part thats bad

Not sure how Battery is being tested, but if jumping works then replace battery

 

I appreciate your time on this bro. And I understand about the battery just being the starting point. And it was only at the beginning of all of this that it would accept a jump start. Presently I can't push start it out jump it or nothing.
I'm gonna go ahead and put my Motocraft battery in it from my f150 and see what happens.
I'll let you know from there.
Also, can a battery show 12.9 volt and still be so defective that it won't power up ANYTHING on the vehicle??

 

Jumping works because you are not using the battery at all
Bump start/push start can't work unless there is some battery voltage, Alternators don't "create" voltage, they need startup voltage to activate, and only then can they generate voltage

Yes, failed battery can show voltage on a volt meter because volt meter draws almost no voltage/amps, key on needs about 10-20amps, starter motor needs 60-75 amps
Test while some one has key on and turns it to START
And have volt meter on the outside of battery terminals not on the center