Engine Battery Keeps Dying

[Gideon33w]

Holy crap, pull the positive battery wire and run a multimeter between the batt and cable with everything off.
If there's amps being drawn then it's parasitic loss. If not, then it's something else. Likely alt/batt cabling.
We can't figure it out or solve it through the Socratic method. Let's see what the test shows please.

 

[HumbleBeginnings]

Have you had a chance for any voltmeter tests yet?

Note that you will expect to find some current no matter what, but if everything is okay it should be somewhere in the range of ~25-100mA. This is from keeping your radio clock, presets; can also be for the car's computer memory, etc (hence why disconnecting the battery clears trouble codes).

I couldn't remember how much current to expect in a normal condition, so I had to look it up.

 

[Gideon33w]

Should be obvious if there's any real amps being pulled. It will be enough to spark most likely.

 

[JustACarSoFar]

Should be obvious if there's any real amps being pulled. It will be enough to spark most likely.

Hey guys, this is exactly what I'm dealing with in the car battery! Frkn hell of a pain in the ass mystery, even after having it in the shop
once already.
They tested' like you said.. and could not find a draw that would kill a battery overnight. wel... something still does...and
it would NOT happen while at the shop!  
As a side deal.. they had to replace the sensor thing.. it was going whacko as I brought it there and they said it completely died
when the car arrived,.. could not have been driven at all, as was.
So.. thinking THAT was the start issue also.. thought we had if figured out.
After a couple days of acting OK... it happened again.  Only.. unlike the former times, where it was completely dead.. this last time
there was enough juice to let door lights come on and gauge needles to fly around crazy.. and it "clicked" with no turn over.
a few hours later, was completely dead like before soo..

I'm sure it's not alternator as it did charge up after a long drive. besides, sure the mechanic tested that.  He feels so bad this
did not happen while under his 48 hour watch!  I'm so depressed, can't afford to take it back to shop this month.

question.  If I get it jumped once again, and charged up.....  can I at least disconnect the battery each night.. so it will run again
the next day?  and do you have to pull the whole battery out??

 

[HumbleBeginnings]

To save the battery's charge, all you have to disconnect the negative battery cable. To make life easier, you can install a quick disconnect. If your problem is parasitic drain, that will keep you running until you find the source of the problem.

 

[Motrukdriver]

My Jeep does this and I researched how to fix it. Just like Gideon says, one circuit at a time till you find the problem. I'm gonna address my drain issue when I get back to the US but for now I just take the negative terminal off the battery at night. Gotta get that Cherokee ready to pull.

 

[JustACarSoFar]

Should be obvious if there's any real amps being pulled. It will be enough to spark most likely.

Guess wut!  I got jumped, drove 3.5 hours to charge her up.. came home.. disconnected a smaller, back post/plug on pos side..
(cuz triple A guy said that was easiest to get to) and voila!  it SPARKED on meh!  I was askeeerd.. and now tomorrow,
have to do the SPARK test on ALL the fuses.. there's so many!

nothing like.. man... not really looking forward to SPARKSville.. but gotta do er!   wish me lux!

 

[Gideon33w]

You could use a cheap multimeter or a 12v light instead of relying on sparks.

 

[jonyjoe303]

disconnect the negative so you don't get sparks, if the plus terminal touches anything you will get sparks everywhere. even disconnecting the plus is dangerous if the wrench touches something you get sparks. The negative cable is connected to all the metal parts in the car and its "live" while its connected to battery. If you need to keep disconnecting the positive terminal, at least you need to cover it in plastic so it don't touch any metal.

Another thing that will keep you battery from charging up is loose terminals or a bad connection anywhere on the terminal cables. It will feel like you have a parasitic draw, but its actually the cables just not passing enough current to fully charge the battery, one sign of this is slow cranking after being park overnight. I had slow cranking for years and replaced several batteries to find out I had a loose terminal (sidepost) that didnt bolt all the way down. Car will run perfect when running but just not charging you battery fully, if you can't find nothing else wrong replace the terminals (side or top posts) or checked that the terminal cables are tight everywhere, even a little looseness will cause you problems. Check both plus and negative cables.

battery terminal cable

 

[user 2252]

Please be careful with "sparks". Batteries give off a gas, a explosive gas.

 

[Gideon33w]

Please be careful with "sparks". Batteries give off a gas, a explosive gas.

A tiny amount of hydrogen when charging. Unless you're in an enclosed space with an actively charging battery it's not actually a concern.
Keep in mind, most batteries are in engine bays with exhaust manifold temps exceeding hydrogen's auto-ignition temp and yet no issues.

 

[UptownSport]

They'll blow up with a big spark if it just got a big charge.

Taking the 5th ...