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Can't keep a charge

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Old May 10, 2011 | 02:56 PM
  #1  
danewbern's Avatar
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Can't keep a charge

Guys-

I have been chasing a problem for a while and was hoping someone could help. I did a conversion to a vmount IC last year and relocated my battery to the bin behine the driver. At rotary performances reccomendation, I used a miata battery and connected the positive to the starter. For some darn reason, it can't keep a charge on the battery. After I put it on my charger, it powers full charge but there is not enough juice to do anything.

I even tried swapping to a new battery. Aftter a month, I am dead in the water again. Does anyone know of a good way to tell if there is a constant drain on power and how I can track it down?

Thanks,

Dan
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Old May 10, 2011 | 05:04 PM
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Put a DVOM in series with the battery (dvom negative lead to battery negative post, and dvom positive lead to battery positive post)

All doors "closed" (I recommend having them open and use a screw driver to lock them that way ur interior lights will not stay on)

Then put the DVOM in AMP setting to see what kind of amperage draw you have after 30 minutes sitting.

It should stay below 200mA. If you have something higher than that, start pulling fuses one by one and check the amperage draw. The one fuse that you removed and the amperage draw drops, you found the circuit for the draw.

Then start from there to figure out what's draining the battery dead.

-AzEKnightz
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Old May 10, 2011 | 07:27 PM
  #3  
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It should stay below 200mA.
Our '94 reads about 13 mA.
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Old May 11, 2011 | 11:04 AM
  #4  
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Originally Posted by AzEKnightz
Put a DVOM in series with the battery (dvom negative lead to battery negative post, and dvom positive lead to battery positive post)

All doors "closed" (I recommend having them open and use a screw driver to lock them that way ur interior lights will not stay on)

Then put the DVOM in AMP setting to see what kind of amperage draw you have after 30 minutes sitting.

It should stay below 200mA. If you have something higher than that, start pulling fuses one by one and check the amperage draw. The one fuse that you removed and the amperage draw drops, you found the circuit for the draw.

Then start from there to figure out what's draining the battery dead.

-AzEKnightz


/\this is wrong.


disconnect the battery neg
clamp the Multi meter lead to the neg battery terminal
clapm the pos lead to the neg battery cable (while not attached to the battery)
set the meter to amps

if you do it across the battery terminals it will blow the meter fuse
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Old May 11, 2011 | 01:48 PM
  #5  
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Originally Posted by mad_7tist
set the meter to amps

So what's a good reading threshold?
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Old May 11, 2011 | 02:10 PM
  #6  
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less than 100mA. less than 50mA ideally some aftermarket stuff will change that like an alarm etc
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Old May 11, 2011 | 03:04 PM
  #7  
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thanks for answering.
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Old May 11, 2011 | 03:44 PM
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Thumbs up

Originally Posted by mad_7tist
/\this is wrong.


disconnect the battery neg
clamp the Multi meter lead to the neg battery terminal
clapm the pos lead to the neg battery cable (while not attached to the battery)
set the meter to amps

if you do it across the battery terminals it will blow the meter fuse
LOL, thanks for catching it. I meant

"DVOM negative lead to negative post while DVOM positive lead to GROUND CABLE."

By the way, I also meant 20mA NOT 200mA. But as mad_7tist stated, 50mA should be ok if you have aftermarket alarm and sound systems installed.

My apologies, I was busy at work and had couple of mistakes.

-AzEKnightz

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Old May 14, 2011 | 01:12 PM
  #9  
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From: Plano, TX
Thanks Guys. I'll give it a try and report back
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