• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

Battery drain

wal1210

Contributor
Newbie
Joined
Aug 11, 2017
Messages
34
So, I've got something thats draining my battery. When I initially hook my battery up, there's always a spark to my negative cable, and if i leave the battery in for more than 24 hours, my battery is drained to the point that it doesn't have enough juice to start the bronco. I know that a faulty alternator is a common source of battery drain, so is there any way I can check this? Is there anything else I should check before I commit to a new alternator? My engine bay is pretty much stock and I've basically replaced the whole starting system (solenoid, starter, wires, battery, ignition switch). Thanks in advance.
 

bronconut73

Bronco Guru
Joined
Aug 7, 2012
Messages
9,916
X3.

It was all coroded behind it. Make sure you do not plug the new one in unless it is mounted to the firewall. It needs a clean spot to mount as it gets its ground there. Mine also had a terrible ground quality. New regulator and raw metal for the regulator to mount against and all was well.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
The easiest way to check is to, with a fully charged battery, disconnect the regulator overnight to see if it still drains.
If it does, then do the same thing, but disconnect the main charge wire from the alternator instead.
You can access it from the back obviously, which is a bit of a pain. Or on most years of EB you can disconnect the 3-wire(?) plug that the alternator's Black w/yellow wire is part of.

If it still drains overnight, even with those items disconnected, then it's looking more likely the battery itself is compromised.

A little bit of spark is almost universally expected the first time you touch the cables to the terminals on the battery. But a nice healthy snapping spark is definitely indicating some extra draw through the system.

Paul
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
Sorry, meant it's the easiest if you have the time.
A better way to check would be to look for the drain yourself while you're disconnecting the two things. With a test light or meter you can see the drain through the battery cable.
The problem I see with this is that an alternator might be pulling more than the 10a that a normal test light can handle.
AT least I seem to remember them being fairly weak and when testing for current flow through a disconnected battery cable they can burn out the lamp if it's not fused, or rated for higher currents.

Good luck.

Paul
 

sprdv1

Contributor
REBEL
Joined
Mar 8, 2007
Messages
81,734
The easiest way to check is to, with a fully charged battery, disconnect the regulator overnight to see if it still drains.
If it does, then do the same thing, but disconnect the main charge wire from the alternator instead.
You can access it from the back obviously, which is a bit of a pain. Or on most years of EB you can disconnect the 3-wire(?) plug that the alternator's Black w/yellow wire is part of.

If it still drains overnight, even with those items disconnected, then it's looking more likely the battery itself is compromised.

A little bit of spark is almost universally expected the first time you touch the cables to the terminals on the battery. But a nice healthy snapping spark is definitely indicating some extra draw through the system.

This.....^^^
 
OP
OP
W

wal1210

Contributor
Newbie
Joined
Aug 11, 2017
Messages
34
Hmm, ok I'll give those a try. I will say, I pulled the voltage regulator to check it out and the terminals were pretty corroded. Thanks for the timely replies, y'all rock.
 

Attachments

  • IMG_20180722_200240.jpg
    IMG_20180722_200240.jpg
    69 KB · Views: 31
Top