# POWER DRAIN



## ericwillard (Feb 27, 2005)

I have a 96 maxima that is draining the battery overnight. It is drawing 65 amps when shut off. The power antenna went a while back, which may be the problem. Any easy way to disconnect the power antenna? Where is the fuse?


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## shoe_shiner (Feb 4, 2005)

*antenna wtf?*

ive never heard of the antenne draining that much power. umm i dont think there is a fuse for it either but if there is one it would mostlikely be in the interior fuse box. is ur check engine light on for this? also hows ur alternator doin? maybe its not charging the battery. to disconnect the antenna go in the trunk and disconnect the connection. i personally dont think its the antenna tho.


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## Matt93SE (Sep 17, 2003)

65 amps?!?!

you got something majorly wrong in there... whatever it is, it will be HOT... 65A * 12V = 780W.. and since there's nothing moving, the only place it can go is heat.. 

780W is a hairdryer on med... just to give you an idea of how much heat you're talking about.

so if you're drawing 65A, something is goign to catch fire soon, or be very easy to find.


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## ericwillard (Feb 27, 2005)

65mA, sorry. Normal draw when the key is off is ~25mA.


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## Matt93SE (Sep 17, 2003)

ahh, that's better.. 
65mA is still nothing to worry about.. that's 1/2 watt. that could be something as simple as a door pin switch that's not closed or something, or your clock is acting funky.

the tiny light bulbs in your map lights are 5W, and should be able to stay on for days without running the battery down.


as for the power antenna, just pull the liner off the trunk wall and disconnect the wires going to it. easy enough.


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## ericwillard (Feb 27, 2005)

Matt93SE said:


> ahh, that's better..
> 65mA is still nothing to worry about.. that's 1/2 watt. that could be something as simple as a door pin switch that's not closed or something, or your clock is acting funky.
> 
> the tiny light bulbs in your map lights are 5W, and should be able to stay on for days without running the battery down.
> ...


The power antenna has been removed and the draw is still the same. I have never used a voltometer, and would just like to double-check that I'm reading it right.

Is this the way it should be set up? The photo came out a little washed out so I painted in the needle and markings on the dial.


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## Matt93SE (Sep 17, 2003)

Ummm, you're reading DC volts on a 15V (max) scale.

By disconnecting the ground on the battery, that gives everything else on the car a charge of +12V, so when you measure against battery ground, the other end is like touching the + post of the battery since it's still connected. make sense?

I wouldn't try to do a current measurement with that meter. the max it will show is 150mA (it's the setting just to the right of OFF). any more than that and you will damage the meter- usually just blows a fuse, but you still don't want to use that as a safety against blowing up the meter.

reason I'm saying that is that if your battery is dying overnight, then the battery itself is on its way out, or you're having way more than 150mA drawn from it. 

a standard car battery is holds around 65Amp-hours..  so if you're pulling 1A of current off it, it will last 65 hours on one charge. thus to kill the battery overnight (10 hours), you'll be drawing close to 6.5A. that's over 40x the 150mA capacity of that meter.. make sense?


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## Imobejoas (Jul 4, 2003)

I'm guessing dead battery can't hold the charge no mo

And I didn't quite understand what Matt was saying there. I would figure you would read current off the positive terminal, though it shouldn't really make a difference since what goes out must come back.


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## Matt93SE (Sep 17, 2003)

The setting he's got on the meter is to read voltage, not current.


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## brianw (Feb 25, 2004)

That's the proper method for measuring current, but that little meter would die (and possibly do other unpleasant things with it) if you tried to measure current that way. If you must measure current, a clamp-on ammeter is a safer way.


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## Matt93SE (Sep 17, 2003)

clamp-on ammeters don't work accurately for DC, only AC.


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## Imobejoas (Jul 4, 2003)

Matt93SE said:


> clamp-on ammeters don't work accurately for DC, only AC.



No, that's incorrect. Clamp-on ammeters should be able to measure both AC and DC, but are not as accurate due to physical constraints.


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