How to test for electrical drain?

M3_Dylan · 08-03-2014, 07:52 PM

What the hell am I doing wrong here? I have been fighting with this mysterious battery drain that kills a 100% charged battery over night

So I went out and bought a multimeter and un-hooked the negative battery terminal and hooked one lead to the negative battery terminal and the other to the chassis wire. It then reads 12.6V I pulled all the fuses and that reading does not change. Please help

Ingeniator · 08-03-2014, 07:57 PM

You need to measure the amperage not the voltage. Make sure the car is asleep.

M3_Dylan · 08-03-2014, 08:32 PM

Quote:

Originally Posted by Ingeniator

You need to measure the amperage not the voltage. Make sure the car is asleep.

When I set it to the 10 AMP setting it reads 0.00 which cant be right

there must be some trick im not getting here

Ingeniator · 08-03-2014, 08:50 PM

Well you want no amp draw but if you have a parasitic drain that kills a battery overnight it should be picked up at 10amps. What happens when the car wakes up/4ways on you get a draw then?

4doorbmwpower · 08-03-2014, 09:49 PM

subscribed.. i have had a draw also. im so scared to even let my car sit without the BMW smart charger because it has caused the ignition interlock twice now and that is a PITA.

Hierlevelz · 08-04-2014, 11:31 AM

You have to set the meter to measure amperage and pull the fuses one by one. And note any drop in amps. If the amperage drops when you pull a particular fuse then the circuit associated with that fuse is the culprit.

08-03-2014, 07:52 PM	#1
M3_Dylan Lieutenant 32 Rep 520 Posts Drives: 2008 BMW M3 Join Date: Sep 2011 Location: Orlando iTrader: (5)	How to test for electrical drain? What the hell am I doing wrong here? I have been fighting with this mysterious battery drain that kills a 100% charged battery over night So I went out and bought a multimeter and un-hooked the negative battery terminal and hooked one lead to the negative battery terminal and the other to the chassis wire. It then reads 12.6V I pulled all the fuses and that reading does not change. Please help __________________ KW V3's / AA Stage 2 Supercharger / Catless Mid-pipes / AA Mufflers / Apex Arc-8's / PFC 09's
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08-03-2014, 07:57 PM	#2
Ingeniator Major 34 Rep 1,093 Posts Drives: 07 335XI(90) 09 135I(82) Join Date: Nov 2013 Location: Fort Mac, Alberta iTrader: (1)	You need to measure the amperage not the voltage. Make sure the car is asleep. __________________ 07 335XI (A008006) 6AT ~94K miles JB4 G5 ISO VSRF DP's 09 135I M (VK80379) 6MT. Race Project car. 1) Install Cobb/piggyback? and Motiv 600 Kit[HTA3076R w/ tial .82] 2) JRZ or Moton suspension. 3) Build high flow intake manifold with multi-port fuel and relocate OFH 4) Build full cage 5) Complete staged twin setup with HTA4205R [w/Tial 1.16] 6) Complete dry sump system
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08-03-2014, 08:50 PM	#4
Ingeniator Major 34 Rep 1,093 Posts Drives: 07 335XI(90) 09 135I(82) Join Date: Nov 2013 Location: Fort Mac, Alberta iTrader: (1)	Well you want no amp draw but if you have a parasitic drain that kills a battery overnight it should be picked up at 10amps. What happens when the car wakes up/4ways on you get a draw then? __________________ 07 335XI (A008006) 6AT ~94K miles JB4 G5 ISO VSRF DP's 09 135I M (VK80379) 6MT. Race Project car. 1) Install Cobb/piggyback? and Motiv 600 Kit[HTA3076R w/ tial .82] 2) JRZ or Moton suspension. 3) Build high flow intake manifold with multi-port fuel and relocate OFH 4) Build full cage 5) Complete staged twin setup with HTA4205R [w/Tial 1.16] 6) Complete dry sump system
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08-03-2014, 09:49 PM	#5
4doorbmwpower Captain 63 Rep 954 Posts Drives: Montego Blue E90 335i Join Date: Nov 2010 Location: North Carolina iTrader: (3)	subscribed.. i have had a draw also. im so scared to even let my car sit without the BMW smart charger because it has caused the ignition interlock twice now and that is a PITA. __________________ cp-e GTX3071R TT kit, cp-e quad exhaust, cp-e fuelbar, Stage 3 LPFP+lines, AEM EFI, Custom Meth kit, Apex EC7 18s w/R888 295s, Stoptech, M3 front, m-sport rear, cp-e difuser, Custom Headlights, CFS Radiator, Custom OC, 1000hp Lvl10 trans, DSS Axles, MFactory LSD, DEFIV lockdown kit, M3 refresh kit, KWv2's, cp-e project "4doorbmwpower"
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08-04-2014, 11:31 AM	#6
Hierlevelz Captain 76 Rep 917 Posts Drives: 11 AW E9X M Join Date: Dec 2011 Location: ENYC iTrader: (10)	You have to set the meter to measure amperage and pull the fuses one by one. And note any drop in amps. If the amperage drops when you pull a particular fuse then the circuit associated with that fuse is the culprit.
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