Don't do this - drained battery

KCsTJ

KCsTJ

TJ student
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Jan 9, 2018
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Farmersville, TX, United States
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I like to hang my shop light from a factory hole under the hood when I'm working on my 97 TJ.
The light is connected to a short extension cord plugged into the 110v wall outlet.
Well, couple nights ago I forgot to unplug the light (No on/off switch) from the wall outlet.
Next morning the battery was dead as a mackerel.
I guess the ground circuit from the 110v outlet drained the negative side of the battery ?
Just a guess. Put the charger on and after an hour she cranked up.
 
KCsTJ said:
... I guess the ground circuit from the 110v outlet drained the negative side of the battery ?
Just a guess. Put the charger on and after an hour she cranked up.
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Nope that wouldn't/couldn't drain the battery. You've likely got a battery that is going bad, I'd have a good battery retailer perform a "load test" on it. And an hour isn't enough for a battery charger to completely recharge a dead battery. Overnight is best.
 
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alittleoff said:
The pic doesn't show it, but did you unplug the factory under hood light?
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That's exactly what I was thinking ...maybe it was the under bonnet light that is the guilty one. I remember my kids leaving the interior light on and the battery would be flat as a pancake by morning.
 
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Kiwi TJ said:
That's exactly what I was thinking ...maybe it was the under bonnet light that is the guilty one. I remember my kids leaving the interior light on and the battery would be flat as a pancake by morning.
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It is important to either unplug that light or close the bonnet if you want to leave it plugged in but aren't working on it

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To add to Jerry's response, not only should you let it charge overnight it should be a 2 amp trickle. Most new battery chargers do that automatically, but wouldn't you know it, I have a battery charger that still works but does not automatically trickle, so that is why I warn. If it is digital it should tell you how it is charging. If you blast it for an hour you get a surface charge that will fail a load test, but if you let it trickle overnight it will get fully charged, and will give you a more accurate load test the next day.

Just to back up what he said unless there is a freak of physics that I am not aware of your 110 light did not drain your battery. Maybe one of your doors wasn't shut all of the way? A dome light can take out a battery overnight?

Lastly if you have money to burn, have you seen my How-to on dual batteries? Just sayin!!
 
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ac_ said:
To add to Jerry's response, not only should you let it charge overnight it should be a 2 amp trickle. Most new battery chargers do that automatically, but wouldn't you know it, I have a battery charger that still works but does not automatically trickle, so that is why I warn. If it is digital it should tell you how it is charging. If you blast it for an hour you get a surface charge that will fail a load test, but if you let it trickle overnight it will get fully charged, and will give you a more accurate load test the next day.

Just to back up what he said unless there is a freak of physics that I am not aware of your 110 light did not drain your battery. Maybe one of your doors wasn't shut all of the way? A dome light can take out a battery overnight?

Lastly if you have money to burn, have you seen my How-to on dual batteries? Just sayin!!
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Yes I like your dual battery setup ac_. This battery came with my Jeep so i have no idea how old it is. Think I'll err on the safe side and replace it, thanks for the responses :)
 
KCsTJ said:
Yes I like your dual battery setup ac_. This battery came with my Jeep so i have no idea how old it is. Think I'll err on the safe side and replace it, thanks for the responses :)
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To be on the safe side, have it "load tested" by a good battery shop before paying for a new battery. A load test, when properly performed, will tell you the true health of the battery and whether it is in need of replacement or not.
 
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Jerry Bransford said:
To be on the safe side, have it "load tested" by a good battery shop before paying for a new battery. A load test, when properly performed, will tell you the true health of the battery and whether it is in need of replacement or not.
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will do Jerry, thanks I'll get it load tested.
btw I do remember a digital 'bad' display on the charger, briefly, so u may have nailed it Jerry (again) :)
[ I wonder if he gets tired of being right so often ] ;-)
 
xxdabroxx said:
Don't bump your electric locker switch while cleaning the dash and not notice it either. That will kill your battery too. Don't ask how I know...




And no, I still haven't run it through a switched relay.
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Same with your York compressor clutch switch. Don't ask how I know. Someday I need to move the switch to a keyed circuit.
 
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