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    #1

    Battery issues

    I have constant issues with the battery being drained. The P/O stated that the battery is new, and he believed that there was a parasitic drain causing the issue, so he had a shut-off valve installed just to keep the battery alive in the interim.

    I thought I had diagnosed the parasitic drain successfully (got it down to < 0.10 amps, iirc), but even after using the shut-off switch, the battery is still draining.

    Any ideas on how I can diagnose this? I don't want to go spend $100+ on a new battery only for that one to keep dying on me when the issue is something else.
    Tags: None
    #2
    Normal parasitic draw would be 30-60ma. Place a DMM between the negative battery terminal and the ground cable and see what the current is. If more than normal pull one fuse at a time to find the offending circuit. Then trouble shoot that circuit.

    The other possibility is an alternator fault. At idle system voltage should be ~13.6v, rising to ~14v at 2500rpm. Loading the system by turning on the headlights and the HVAC blower to max should not significantly affect system voltage.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

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      #3
      .1A is 100mA, which is double my acceptable standard. When you hooked your meter up, how much time did you give for everything to shut down? Depending on the vehicle it can take up to 30 mins to drop below 50mA.

      If it's below 50mA, then yes, you could have an alternator issue.

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        #4
        Interesting, thanks guys!

        There was at least an hour or two before I tested it at times, because I was doing other things.

        It was much higher initially, up to 0.7A, until I pulled each fuse one-by-one. I isolated it down to Fuse 21 and Fuse 27, I think.

        The one issue I was able to identify was driver's side heated door lock. I disconnected that and it hit < 0.1A. Glad to know that it needs to be 0.5A, so I'll keep trouble shooting it.

        I'll check for the alternator.

        Comment

          #5
          Battery issues

          Okay, did some more testing. Let the car idle for 10mins.

          Car off, battery is 11.25V
          Car on at idle, battery is at 13.35V
          Car on at idle, loaded system with air to max (AC is blown) and headlights on, battery is at 13.10V

          Testing for parasitic draw again, Fuse 21 is causing a 0.7A draw. With trunk light connected, it's around 0.37A. With Fuse 21 and trunk light disconnected, it reads 0A.

          Thoughts?

          EDIT: The longer I let the car idle, the more the voltage drops on the battery. It's down to 13.25V, and when I just started the car it was at 13.45V. Final readout before I turned the car off was 13.16V.

          EDIT2: After letting the car sit for 30 minutes, I checked the battery again and it is now at 11.85V
          Last edited by damir; 09-02-2013, 11:54 AM.

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            #6
            Btw man - 50mA = .05A. .5A is 500mA, which is ten times my standard limit. Also, I'm questioning the effectiveness of your meter... never seen a car that drops down to 0A. Either that, or you've got the range set wrong.

            Also, if your voltage is dropping while the car is running, you've got one of two problems:

            A. Crap alternator

            B. Bad connection to the alternator or battery. Check your cables.

            Comment

              #7
              I'll take a pic of my setup later. Thanks for all the help.

              FYI, at last shut-off, my battery was at 11.99V. This morning I checked it again and it was at 11.8V -- with the negative terminal disconnected, so there was no draw on it.

              Comment

                #8
                Hmmm.... well, that's weird. Could just be that your battery cooled off after running (batteries that are charging are warmer) or that when you checked the battery initially the ambient air temp was higher.

                One thing noone asked though... does this battery look new, like the PO stated? I ask because some people have a very vague definition of what 'new' is. I've fixed 'new' lawnmowers for people before who consider them new because they've only been used a few times, but disregard the fact that they bought it and the gas 5 years ago. Just saying. Also, what brand of battery is it? Walmart-ish?

                Comment

                  #9
                  Originally posted by jalopi View Post
                  Hmmm.... well, that's weird. Could just be that your battery cooled off after running (batteries that are charging are warmer) or that when you checked the battery initially the ambient air temp was higher.

                  One thing noone asked though... does this battery look new, like the PO stated? I ask because some people have a very vague definition of what 'new' is. I've fixed 'new' lawnmowers for people before who consider them new because they've only been used a few times, but disregard the fact that they bought it and the gas 5 years ago. Just saying. Also, what brand of battery is it? Walmart-ish?
                  Battery has a manufacture date of somewhere in 2011 iirc. So it could have been sitting a year or two. It's an Exige "classic" (the ones they sell at Baxter, a local autoparts store).

                  I had them check the battery, the diagnostics came back as "Good charge", but it only had 450CCA versus the 650CCA it was rated for.

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