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Testing Your Battery for Parasitic Load

Testing for Parasitic Load

Testing a system for current drain

To check if something is draining your battery while your bike is turned off you need to test for current, not volts. To do so, do the following:

Switch your Digital Multimeter to DC AMPs. Amps is usually indicated by an "A" on the Multimeter Switch. AC is usually shown as a "~" symbol and DC shown as a "-" symbol. You usually have to move the Multimeter positive lead to a separate socket on the Multimeter. Sometimes there are 2 sockets, a high range and a low range. Always test on the highest setting first. For example: high setting on your multimeter may be 10 Amp. Test on the 10 Amp setting first, then if the current drawn is less than your Multimeter Low setting, move to that setting and keep testing. In my example my Multimeter low setting is 0.3 Amps. Also indicated as 300mA (mA x 1000 = A).

Digital Volt Meter # YDMM05WARNING! Once the multimeter is on Amps do not connect it directly across the battery and do not hit the starter button while testing for current Amps. This will cause the internal fuse in the multimeter to blow! A multimeter set on current is a very low resistance, almost a short circuit and will draw as much current as your battery will supply till something melts. Always plug the Multimeter leads back to volts when you have finished testing to avoid blowing the fuse next time you use your multimeter.

Voltage ReadingTo test for battery drain: Switch everything off on the bike. Disconnect just one battery lead. For example disconnect the Positive Battery Lead. Set your Multimeter to Amps as described above. Connect the Positive Multimeter Lead to the Battery Positive terminal. Make sure the Positive Lead you removed from the battery does not touch anything grounded, like the Bike frame etc…. Connect the Negative Lead from the Multimeter to the Positive Lead you removed from the Battery. You should now see current drain measured in Amps. Move to the lower Amp setting on your multimeter if the current is lower than the setting on the Multimeter Low setting. Start to unplug the wires or fuses around your bike and see if the current reading goes to zero. This will point you in the direction of the current thief. You can convert to Power measured in Watts by multiplying it by the Battery Voltage. Power = Volts x Amps 4.2Watts or (12Volts x 0.35Amps).

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6 people commented, JACK, Tech, Another Reader, Jeremy Fear, and 2 others
This article is rated 2.5 out of 5
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  • Just A Reader
    is more safe to disconnect negative lead, is touch chassis, nothing happen…

    Reply  •  August 16, 2012 at 6:39 am
    • Jeremy Fear
      When disconnecting, or connecting a battery to a negative frame grounded application, it is always safer to connect/disconnect the possitive lead first.

      Reply  •  August 16, 2012 at 9:45 am
      • Another Reader
        You sir are wrong. It is an old “wives tale” to remove the HOT side first. Very simply, you remove the lead that will remove the most exposure to a short circuit. In this case, the entire chassis is equal to the negative lead, therefore that is the one to remove. As stated above by Mario, you would not want you wrench to hit a piece of the frame while disconnecting the HOT side…. Whereas, if you accidentally short while disconnecting the NEGATIVE side, NOTHING HAPPENS.

        Reply  •  Rated article 4  •  December 16, 2012 at 7:20 am
        • BatteryStuff Tech
          You are correct. Let me re-phrase my suggestion:

          When you connect a battery to a negative grounded system, then the safest terminal to connect first is the positive terminal. When you disconnect, you want to disonnect the negative first. The whole point is to remove the possibility, or lower the likely hood, of a short. When first connecting, that means that the positive goes first, and when disconnecting, that means the negative goes first.

          Reply  •  December 17, 2012 at 3:11 pm
          • JACK
            Neg. first off and last on.

            Reply  •  July 7, 2013 at 2:52 pm
  • Mario Rom

    Reply  •  Rated article 1  •  June 13, 2012 at 6:57 am