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Senior Charter Member
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939 Posts
Discussion Starter · #1 ·
Ok, I admit it, I'm Lazy but I thought you guys would save me alot of time.
Here's the scenario: Try to start car after 2 days and no go, charge batery up, starts right up and runs fine. when running voltage is over 12v
next day starts fine but if I let it sit 2 or 3 days it needs charging again.
Optima battery about 1 year old but its been like this since the beginning.
How do I find the thing that's draining down the battery? Is there a methodical approach? thanks, Karl
 

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Senior Member
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2,860 Posts
I have found 'Clamp Meters' to be invaluable. Just clamp around the wire/cable (starting at the battery), and check the amp load. Don't need to disconnect anything. I have the Fluke; but Sears sell a great unit for less than $100. Besure it measures DC amps ...many don't.

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&pid=03473756000&cat=Electrical+Shop&subcat=Multi-Meters,+Testers+%26+Accessories&vertical=TOOL&ihtoken=1

Great way to test Amps for starter...have someone crank; you measure. :D

 

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FFCobra Master Craftsman
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2,040 Posts
You should see between 13.5 - 14.5 volts at idle. If you see 12 something volts it is not charging.
To find a draw on your battery disconnect one battery cable (your choice) and hook up a test light. Hook the test light up so it replaces the batty cable connection. In other word attach one end of the test light to the battery and the other to the cable you just disconnected. Skip the next step if you have a carb and no radio. If you have a injected car or a radio this is the important part with the test light in place (and don't lose connection) touch the battery cable back to the terminal on the battery for 10 seconds. This will energize the memory for the computer and radio if you have one.
Is the test light on? If the light is on unplug your alternator and see if the light goes out (my guess). The next step is to pull fuses one at a time until the light goes out. If it is still on disconnect the wires at the starter relay one at a time until it goes out.
Jeff Hamilton
 

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Charter Member
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1,098 Posts
Go to the fuse panel. It's easiest to find, or intentionally blow a fuse. With the battery switch in active, but the ignition off, methodically remove one fuse at a time and insert the blown fuse in it's place. Using a current meter with 20A capability measure the current flow through that circuit. If you find a circuit with current draw you found it!

I found a bad door lock switch in my daughter's Jeep this way. Now the battery stays charged.

HTH,
Robert
 

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FFCobra Captain
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11,720 Posts
Did you use the donor harness? If so, then most of the things that were 'stock' should be OK.

I had a similar problem. What I found was that when I added a relay for the fan switch, I connected the wrong part of the relay to an always hot circuit in the fusebox. That caused a drain that would eat up the battery in the same amount of time.

Check your fusepanel for the circuits that are always hot and see what you have hooked up to them and make sure the relays are connected properly.
 

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Senior Charter Member
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939 Posts
Discussion Starter · #6 ·
Thanks guys this gives me someplace to start. Aloha, Karl
 
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