19-05-2013, 07:51 PM
(19-05-2013, 07:31 PM)andywhy Wrote: Put your multimeter inline with the battery and check the "parasitic" current. Disconnect both terminals (neg first for safety). Put the positive terminal to positive of the meter, then the negative of the meter to the positive cable going to the car. Put the negative on the battery as normal. Put it into 10A mode (remember to move the probe to the other socket) and see how much drain you get. Don't try to start the car or turn lights/ignition etc on, or you'll probably damage your meter. Just make sure doors are locked, etc, just as you would when you walk away from it after driving.
Anything around 0.10A or under is normal. You might want to let the car settle for 5 minutes after you make the connection as the ECU might draw a few amps for a while.
Anything over 1.00A would likely cause you to have low battery symptoms after 12 hours or so, especially if you have a weak battery anyway.
And make sure you put your probe back in the volts socket, or you'll get a nasty sparking and smoking surprise next time you try to measure a battery for voltage
Brilliant 'Andywhy' - will do that persactly. Have been trying to figure out how to do that very thing with my new meter from BnQ! Now I can .... and without setting fire to it!