What Can Drain the Battery?

[gooch66]

Beside the obvious stuff like lights, what else can drain a battery while the Bronco is not running? I have a terminal block on my fender well for lights and that is the only 'extra' piece of the electrical system. Suggestions?
Thanks!

 

[bronconut73]

A short.

Put an ohm meter on the battery then pull one fuse at a time.
That's not fool proof but it might help to narrow it down,..,

 

[Specracer]

The alternator its self can, I cant remember the exact component (capacitor etc) that when gets older can steal juice back. Another common item is an aftermarket radio, drawing to keep its memory.

Exactly the reasons I'm diligent to just pull the neutral cable any time they are going to sit for more than a couple days.

 

[Broncomt]

Also, have the battery tested. Even newer batteries can be bad. You may have a weak/bad cell.

 

[bronco loco]

When I bought my bronco I also had a drain, turns out the prior owner installed an edelbrock carburetor choke to a 12v unswitched source.
I could not figure out why the battery charge did not hold charge more than a day and why when i finally started it did not run well at all until it warmed up. The choke was constantly on even when truck was off. After connecting choke to a switched power source, the truck ran much better and battery drain ceased. Check any aftermarket items for voltage source.

 

[half cab]

I have seen stereos hooked up wonky to the harness that woukd cause a drain problem.

 

[blubuckaroo]

Disconnect either the + or - battery lead, and connect either a test lamp or a mutlimeter (set to amps) between the battery post and lead.
If there is a load it will light the test lamp or show on the meter.
Next start disconnecting things by pulling fuses and pulling plugs until the load goes away.
This is how I found my leak. Mine turned out to be the electronic voltage regulator I put in over 30 years before.

 

[Digger556]

The rectifier (diodes) in the alternator have been know to cause a drain when they fail. Their failure can also result in reduced output at high loads or AC leaking into the DC circuit.

 

[SHX669]

I also had an electronic voltage regulator draining my battery.

 

[gooch66]

Thanks for all of the suggestions. Once I get home from work, I am going to start with the fuse box and work my way outside.

 

[rjrobin2002]

I have seen stereos hooked up wonky to the harness that woukd cause a drain problem.

I work at the same hospital as Gooch and looked at his Bronco after work, but am in no way a electrical diagnostic wizard.
We pulled all the fuses one at a time and the drain never went away, even disconnected the alternator and it never went away. I was just touching the positime cable to the positive post and watching a big spark after each fuse was removed to see if a drain was present.

I then started glancing at his stereo power supply, it's constant power supply is soldered to the really large black with yellow strip under the dash. I cut its power supply and the arc reduced 90% and he is gonna see if it drains tonight and I am gonna run him a new power wire off the key switch. What's yalls thoughts?

 

[bronconut73]

I have never tapped into the factory harness for any of my accessories. And I have a lot of accessories for an eb.
Everyone one of them runs on a dedicated harness back to a distribution/fuse block.

35 years.
No electrical issues.

My old man insisted back in the early 80's that I install the marine distribution/fuse block we didn't use on our boat. Also at Dad's urging reworked every ground on the eb.
Still have that distribution/fuse block. Still run dedicated harness's ....

My Dad and my grandfather just didn't think the eb's oem harness was robust enough to add an aftermarket stereo, c.b., scanner, c.b. amp, stereo amp, off road lights, etc...

So my advice, from my good experience's, is run a completely separate harness for everything you add including that stereo.

 

[Rustytruck]

Most old school stock Bronco problem was the brake light switch down on the brake peddle. It gets old dirty and stops self centering leaving the rear brake lights on. Easy to check especially at night. Just look out back. Another common area is the dimmer switch on the floor board. Its in a really bad spot. Gets wet, builds up dirt and wires can get worn. Pull it up make sure everything is in working order.
Other than that the problems are usually owner induced with ill concieved wiring add on's.

 

[Steve83]

Even a trail of electrolyte across the top of the battery can drain it. Rinse it off, charge it, and see if it still drains when NOT connected to the Bronco or anything else.

If there's an amplifier in the Bronco, then that's a likely suspect. Put that and every other detail of the truck into your signature, like Rusty & a few others have. The more info we can see with each of your posts, the easier it is for us to answer you accurately.

Posting pics of what you find & do will also help us help you. It's free & easy - read the first few posts in this thread:
http://www.supermotors.net/forums/thid-5972-how-do-i-post-pictures-sounds-and-or-videos

 

[DINOONE]

If your EFI I find out my computer was drawing.5 volts draining my battery


Sent from my iPhone using Tapatalk Pro

 

[DirtDonk]

And unless someone has mentioned it already, don't overlook the battery itself. They can go bad and drain themselves overnight too.
Sounds like you've got it narrowed down pretty good to the stereo (even if your method is inexact!) so that's a likely culprit.
But as you can tell from all the good replies already, there are quite a few things that can do it!

Good luck.
Nice to have a fellow EB'er willing to help in the parking lot too! Thanks Robin.

Paul

 

[gooch66]

I have a new dimmer foot switch. I even disconnected the radio and left it off for over a week. While I was on vacation for a week, it sat in the garage. When I came home, it started right up. I have checked under the dash for bad connections, the engine compartment and underneath the vehicle. I have noticed a pattern that it happens with wet weather. My first thought is that water is getting in on the driver side and affecting the gauge cluster wiring and the harness under the dash. My floor pan is always damp on the driver side when it rains. This issue is so frustrating.

 

[rjrobin2002]

He has a new battery that did not fix the problem.

 

[rjrobin2002]

Have yall ever seen an ignition switch have an intermittent short? What ever it is, it randomly can drain the new Optima battery in as fast as 2 hrs.

 

[Rustytruck]

I've had ignition switch stick on when you turn off the key. This has happened when the switch hasn't been used for long periods. Several times in long term ownership. The ford switch has wiping contacts so cycling the switch usually several times cleans the contacts and everything operated normally again. You might want to check the headlight switch too since that circuit is live with the ignition off. But that switch is usually pretty reliable if your still running the Ford switch.