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Okay i replaced 1 battery on drivers side about 3 days ago worked fine for a few days then i woke up yesterday morning now both bateries are saying dead the reason the battery died and i had to replace it was because i left my interier lights on overnight i dont think its my alltinator because the batteries charge up after i jumped them yesterday morning but now this morning they are dead again please help?
 

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If you have 2 dead batteries and replace one the other dead one will just kill that one! Replace both... and check your alt to make sure.its charging properly
 

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Discussion Starter #4
how do i check the altinator
 

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Not real sure?... I checked the power on both batteries with a meter with the truck off.... and again with it running if the alt is working you should have about 13-14 volts while running I believe
 

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Like everybody else said. A bad battery will drain a good battery. You should be able to stop in at an Autozone and have them check your alternator/ batteries.
 

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take the negitave cable off of one of the batterys clip that alligator connector of a test light on the cable then touch the test light to the neg post...this will tell you if you have a draw (if you have a fluke meter that is better because it will tell you actually tell you how much draw) but the brighter the light the more draw. then take the little jumper wire off of the alt and see if the light goes out
 

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Always replace both batteries at the same time.
You can go by any major chain parts store and they should have a machine to check the alternator on the truck. Same with batteries.

Never..ever...ever try the old "Just pull the battery cable off the batteries while it's running, if it dies you got a bad alternator" this shi- works on older vehicles that don't rely heavily on computer/electronic to run various systems. This method will fry your ECM if you are not lucky.

^That is just FYI
 

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Never..ever...ever try the old "Just pull the battery cable off the batteries while it's running, if it dies you got a bad alternator" this shi- works on older vehicles that don't rely heavily on computer/electronic to run various systems. This method will fry your ECM if you are not lucky.

^That is just FYI[/QUOTE]

guess i left that part out you do this test with the pickup off....
 

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take the negitave cable off of one of the batterys clip that alligator connector of a test light on the cable then touch the test light to the neg post...this will tell you if you have a draw (if you have a fluke meter that is better because it will tell you actually tell you how much draw) but the brighter the light the more draw. then take the little jumper wire off of the alt and see if the light goes out
This does not work on computer vehicles-- yes, it worked on old non-computer vehicles.


You cannot test for a drain using a test light between the cables -- Any time you pull the cables, the system has to reload the computers, and that can take several minutes.
The best way is to use a multi-meter AMP setting. [usually limited to 10 amps max] Remove one positive cable from the battery, and put the amp meter connection -one on the battery, and one on the cable. Use test leads for good connection. You will not have any reading, because the other battery is still connected. Now remove one cable from the other battery- positive or negative- don't matter. Now the meter should show any discharge in amps. Start by removing one fuse at a time.

Doing the test like this, you still keep the computers charged. :D
 

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This does not work on computer vehicles-- yes, it worked on old non-computer vehicles.


You cannot test for a drain using a test light between the cables -- Any time you pull the cables, the system has to reload the computers, and that can take several minutes.
The best way is to use a multi-meter AMP setting. [usually limited to 10 amps max] Remove one positive cable from the battery, and put the amp meter connection -one on the battery, and one on the cable. Use test leads for good connection. You will not have any reading, because the other battery is still connected. Now remove one cable from the other battery- positive or negative- don't matter. Now the meter should show any discharge in amps. Start by removing one fuse at a time.

Doing the test like this, you still keep the computers charged. :D
ok...just so im clear are you saying that an 03 powerstroke with the 7.3 is not a computerized vehicle??? because that was the newest vehicle i have done it to i guess?
 

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Use a volt meter should be putting 13.9 to 14 volts at idel the turn your AC and lites should still be over 13.5
 

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I am saying that you cannot check electrical drain on a Duramax with a test light!

Every time you disconnect the batteries-- and reconnect them-- the computers have to recharge. You cannot recharge them through a test light! Try it-- disconnect both batteries and then re-connect one. Has a spark doesn't it. How would the test light work-??

You will have to ask about the Powerstroke at their Forum. :D
 

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I am saying that you cannot check electrical drain on a Duramax with a test light!

Every time you disconnect the batteries-- and reconnect them-- the computers have to recharge. You cannot recharge them through a test light! Try it-- disconnect both batteries and then re-connect one. Has a spark doesn't it. How would the test light work-??

You will have to ask about the Powerstroke at their Forum. :D
well im not trying to start a pissing match here :poke[1]: but i guess i should have been more clear...when i have done this test i only unhook 1 battery to do it so there is still power everywhere. now if it cant be done with a test light fine!! thats all i had. when i got back home i used a volt meter (you need to to see how much its pulling) because its always going to draw a little because of the radio, clock, theft system etc... and i have had 3 PSD trucks and have been a memeber of "their" forum for a while now but thanks
 

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If you use a amp meter [many multi meters have them] and remove one cable, connect the ampmeter cables --one to each terminal [battery and cable] The computers will still be charged-- and it will not show much drain, because the other battery is still connected.

If you disconnect the second battery, all the draw will go through the amp meter and you will be able to see how much amps it is drawing. The computers, clock, and radio are are still charged, because the volts is going through the ampmeter.

With a test light-- I don't think it will charge the computers, and etc, because the lamp has a lot of resistance, which lowers voltage.
 
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