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I'm having constant issues with my 2001 7.3 with the batteries being dead every morning and afternoon. I have replaced both batteries in late December and installed a new alternator but there seems to be a draw on them that within a 6-8 hour period the truck will not be able to crank. If anyone has any trouble shooting ideas or has had problems similar to this what did you do? How can I try to find the draw myself without taking it to a shop. This is my daily driver and I need it everyday. Thanks in advance.

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To kill 2 batteries in that short a time, you have a heck of a draw (actually easier to find than a small one though ;))

First thing I would do is to disconnect the GPR (the highest draw you could have). Next, the "Big Three" are Alt, Radio, & Cluster (not sure if any of them could kill 2 good batteries that quickly but, try disconnecting them, one at a time in that order). You just have to wait each time, like overnight, to eliminate them as the cause.

But let's talk about your situation and the specifics...

It sits for 8hrs, you get in and what happens? Totally dead? No dash lights? Cranks a little on the starter? Just "clicks" but doesn't turn on the starter?

We're assuming two things from your post and that is that both the batteries & the Alternator are good. Lets get some specifics there too. Take a meter, a cig ltr adapter (like from a Radar detector or something) and monitor the Voltage in the in-cab "Outlet".

What's the Voltage during the whole process? (after you drive home, 1st thing in the morning, as you crank, while it's running, when you shut it off at work)
 

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To kill 2 batteries in that short a time, you have a heck of a draw (actually easier to find than a small one though ;))

First thing I would do is to disconnect the GPR (the highest draw you could have). Next, the "Big Three" are Alt, Radio, & Cluster (not sure if any of them could kill 2 good batteries that quickly but, try disconnecting them, one at a time in that order). You just have to wait each time, like overnight, to eliminate them as the cause.

But let's talk about your situation and the specifics...

It sits for 8hrs, you get in and what happens? Totally dead? No dash lights? Cranks a little on the starter? Just "clicks" but doesn't turn on the starter?

We're assuming two things from your post and that is that both the batteries & the Alternator are good. Lets get some specifics there too. Take a meter, a cig ltr adapter (like from a Radar detector or something) and monitor the Voltage in the in-cab "Outlet".

What's the Voltage during the whole process? (after you drive home, 1st thing in the morning, as you crank, while it's running, when you shut it off at work)
Yes the batteries and alternator are new. The aftermarket radio has taken a dump but has power (the screen stopped functioning) but I pulled the inline fuse so it has zero power. I have not tried the gpr because even in cold weather when its charged it has zero issues firing up. I have a edge cts programmer that has also taken a dump (screen also) and I have not pulled the fuses to it yet.

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And as of for the batteries being dead most days it will want to roll over and crank but there will be a lack of juice to do it. If I hook up another power source it will crank right up.

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I would start popping the ground cables off each time it is parked, until you have the time to devote to finding the problem

Letting the batteries run down will do permanent damage to them -- causing even the batteries to run each other down because of the inequality of condition and the parallel connection
 

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I know you said the batteries were just replaced but I would take them and get tested anyways. Doesn't cost anything.
 

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I'd do what NoRalPH said, get a voltage reading from somewhere, I would hook right up the batteries and first thing I would unplug is that alternator (whether it is new or not). It would have to be a pretty hot draw so I wouldn't think that would be hard to find.
 

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And as of for the batteries being dead most days it will want to roll over and crank but there will be a lack of juice to do it. If I hook up another power source it will crank right up.

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Are you testing the batteries when "dead" with a load tester? Sounds more like a starter/relay problem IMO
 
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