Best Way to Measure Battery Leakage | FerrariChat

Best Way to Measure Battery Leakage

Discussion in '360/430' started by mountainman3520, Nov 25, 2014.

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  1. mountainman3520

    mountainman3520 Karting

    Nov 11, 2013
    202
    Silicon Valley, Cali
    Full Name:
    Dan Gilley
    #1 mountainman3520, Nov 25, 2014
    I had a dead battery a few months ago after neglecting to attach my trickle charger for a week. Since that time its been worrying me whenever I leave my car anywhere that it could fail to start. So I'd like to confidently resolve the question so I don't worry about it.

    I believe the cause could be one of four:
    (1) Current battery (Odyssey PC1220) could be worn out. I bought the car 10 months ago and have no idea how old the battery is or how it was treated by the prior owner.

    (2) I was using a CTEK 4.3 trickle charger on normal mode and realized a few days ago that I should have been using the cold/AGM mode. I changed it to AGM mode now, but I'd been using it on the wrong mode for 6 months when I had the dead battery.

    (3) Something could be wrong with the charging system (alternator?) causing it to be almost dead when I parked after a long drive and forgot to attach the trickle charger.

    (4) Something could be wrong causing a higher than usual leakage current, discharging the battery in one week when it was left off the trickle charger.

    Did I forget anything?

    I'd like to address and eliminate each of these possible explanations.

    To resolve item (1), I ordered a new Odyssey 34R-PC1500T and will install when it arrives.

    To resolve item (2), I have switched the CTEK 4.3 to cold/AGM mode and will be careful to leave it there.

    I don't know what to do to resolve item (3) or if it is a credible cause. Comments?

    For item (4), I'd like to take some readings and monitor battery drain to compare against expected healthy values. Could someone please recommend the best place to measure, method for doing so, and expected values in different modes of operation? I have a multimeter that can measure current, but I don't have wrap-around clamp current probes. I could get some if that is the optimal approach.

    Thanks!
     
  2. Kevin Rev'n

    Kevin Rev'n Two Time F1 World Champ
    Owner Silver Subscribed

    Nov 29, 2009
    23,081
    Honolulu
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    Kevin
    #2 Kevin Rev'n, Nov 25, 2014
  3. Jeff Pintler

    Jeff Pintler Formula Junior

    Jul 20, 2005
    537
    Richland
    Full Name:
    Jeff Pintler
    #3 Jeff Pintler, Nov 26, 2014
    The lighter socket voltmeter is handy to check voltage with engine off vs. running to verify the alternator is charging the battery correctly. I have had my 348 alternator fail and the dash warning lamp not light so an extra voltmeter is a good thing to have. To measure current you need to connect the digital volt meter in series with the negative battery cable. Usually there is a separate connection on the digital volt meter to measure current. You also want to use a better meter than a $10 Harbor Freight special. On the newer cars, there are many computers that go to sleep for an hour after the car is turned off so current continues to drop from 2.3 amps to 800ma to eventually 30-40 ma at about 45 minutes. Also, every door and trunk and engine lid need to be closed and latched. Also remember batteries have lots of stored energy and can arc weld metal pieces if you are not careful. Just be careful. There are clamp on current probes but all of them are in-accurate at 30ma levels and tend to drift which is very confusing.

    So in a nutshell: Run the meter leads out a lowered window. Use the 10 or 20 amp setting and meter input and watch the reading taper to less than 100ma after about 30 minutes, if the reading never drops below that, then you can start troubleshooting your problem. Eventually, repeat the test and use the 2amp setting and watch the reading taper down to 30-40ma.

    A single light bulb will draw 1.2 amps-800 ma so it does not take long to drain a battery.
    Plus I don't like to leave a charger connected all the time, they fail some times. FWIW. Use the search function and find lots of info on this process.

    Jeff Pintler
    89 348tb, 86tr, 99 360 3-pedal, 05 S-160 Bobcat
     

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