Hey, new here and im about at the selling point. I have a 2001 f150 supercrew 4.6, my issue is with the battery. Ive changed the alternator 3 or 4 times and im constantly charging and changing batteries. Ive replaced fuses in the interior and in the engine compartment! Basically when i run the headlights or the radio at night or if i drive for an extended period and apply the brakes to stop it drains the battery. Ive also changed the alternator and battery wiring harness and the relays i thought would be problematic. Any suggestions or thoughts on what it could be that drains the battery.
ive taken it to a mechanic multiple time and was told the alt and battery are putting out but at a low rate

 

You may have corrosion in the cables.

 

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The battery cables or the the alternator?? The truck itself has probably had 3-4 owners before me and had some REAL "jerry-rigged" wiring. I did see a ground wire from the engine block kinda behind the alternator that leads to the firewall and one of the ground wires to the negative terminal are both kinda fubar'd

 

 

I'd check both. If you have any "jerry-rigged" wiring, then it's hard to say where the problems may lie, since no one knows what may have been done.

 

Get yourself an EVTM for your truck so you can check all of this
Go look at another truck like yours at the junkyard
Make your wiring match that
Use some of the wiring off the junkyard truck, if you need to, or if you can find some good wiring
Start with your negative cable
The negative cable needs to be good, possibly new and go directly to the engine block with a splice to the frame and another to the radiator support
By splice, I mean a smashed wire tab with a hole in it for a bolt to the frame
Then a takeout to the radiator support
That one with your finger on it needs to be there too
That is an additional engine to frame ground
Your Positive needs to go first directly to starter relay and then to the alternator
If the rest of the truck works, the fuse links are good IMO
I'd start there
Good luck

 

First thing I would've done is get rid of this mess. If it's not a problem now, it will be before long.

 

Thank yall for the feedback! Ill definitely get going with solutions and advice. Luckily we have another 01 in the drive but its got the 4.2 but theres still alot of plug-n-play options

 

Without something that looks like this that can measure DC amps when clamped on.... You're probably going to go crazy trying to find what's happening. A clamp on DC ammeter is almost indispensable for troubleshooting drain and charging issues.

Clamp on watch the current drain and start pulling fuses till it stops.
You can also clamp on and see how much current is being supplied to the battery for charging..... I think it's somebody pointed out a bad battery connection can keep it from charging cuz it's high resistance making it think the battery is fully charged when it's not.

Otherwise you usually check the voltage on the battery terminals when the car is running and it should be like 13.5-14.5 if the alternator is charging the battery

...... This is a cheap one but there are lots of options the key is that it can measure DC current not just AC. Mine can measure up to a thousand amps, is handy for checking charging from alternators, starting current, it'll do motor in rush (peak hold), etc too. Extremely versatile multimeter. Mine ranks as one of the best $120 I ever spent imo.