battery drain
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old and in the way
Joined: Jul 1997
Posts: 5,923
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From: Lovely Hueytown Alabama
battery drain
Need an electronics guru… I’m not smart enough to use my tools !!
I have a parasitic drain on my truck battery, over three-four days the battery is dead. I recharged it and am watching the voltage on a meter., In 24 hours it’s dropped from 12.21 to 11.89 volts… so… 4/10s of a volt…
I tried disconnecting all the power sources individually and the only one I see with a draw when the power is not on is the radio/usb charging ports. They are on the same power source in the console. I'm sure the radio needs it to
maintain the settings and the two usb ports have a led light in them...
Using a fluke 87 meter in series with the power and set on the mA scale I get a reading of 127.1 (or so) so that is 127 milliamps, right ?? That doesn’t seem like enough to draw down a 810 CCA car battery in three-four days, does it ??
What else could be causing this ?? I haven't gone thru every circuit on the fuse panel yet, it's a little hard to get to... don't they make a 'hickey-thing' that you use to replace the fuse and measure current draw... kinda looks like a fuse with wires attached ?? what's it called ??
john
I have a parasitic drain on my truck battery, over three-four days the battery is dead. I recharged it and am watching the voltage on a meter., In 24 hours it’s dropped from 12.21 to 11.89 volts… so… 4/10s of a volt…
I tried disconnecting all the power sources individually and the only one I see with a draw when the power is not on is the radio/usb charging ports. They are on the same power source in the console. I'm sure the radio needs it to
maintain the settings and the two usb ports have a led light in them...
Using a fluke 87 meter in series with the power and set on the mA scale I get a reading of 127.1 (or so) so that is 127 milliamps, right ?? That doesn’t seem like enough to draw down a 810 CCA car battery in three-four days, does it ??
What else could be causing this ?? I haven't gone thru every circuit on the fuse panel yet, it's a little hard to get to... don't they make a 'hickey-thing' that you use to replace the fuse and measure current draw... kinda looks like a fuse with wires attached ?? what's it called ??
john
Elder User
Joined: Apr 2016
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Does your truck have an alternator on it? If so, they will drain the battery if there are bad diode(s) in the rectifier inside the alternator. Try disconnecting the alternator to see if the drain stops. An alternator will still charge with bad diode(s) when the engine is running, but usually not to it's full potential. I use a test light in series with either the battery positive or negative terminal and the cable to check for drain. If it lights up, that is enough current flow to drain the battery.
Thread Starter
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old and in the way
Joined: Jul 1997
Posts: 5,923
Likes: 1,052
From: Lovely Hueytown Alabama
that's something I hadn 't considered. I have a one wire alternator.. if I pull the positive wire from the alternator terminal and use an ampmeter in series will it show the draw there ???
thanks
thanks
Elder User
Joined: Apr 2016
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I'm not familiar with one wire alternators. But, alternators, when in good condition do not draw current when the engine is not running. I'd think if something is wrong with the alternator the draw at the battery would stop after disconnecting the one wire from the alternator. If it does, maybe contact the alternator mfg. to get more info on the alternator.
Laughing Gas
Joined: May 2010
Posts: 1,125
Likes: 191
From: Wharton, PA
If you have a parasitic drain from either your radio or USB port I would disconnect then one at a time to see which is causing the draw. One of them most likely has an internal short to ground.
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