Home > Technical (L322) > L322 battery drain |
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Haylands Member Since: 04 Mar 2014 Location: East Yorkshire Posts: 8195 |
You have to disconnect the + terminal of the battery, put your meter in line with the + post to read amps drawn, then remove fuses one at a time until you find the one that has the drain. Make sure the meter can handle the amps and whatever you do don't start the car or even put the ignition on, it will fry the meter...!!
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14th May 2020 9:36am |
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AJGalaxy2012 Member Since: 11 Jun 2018 Location: Gainsborough Posts: 1464 |
Much easier and safer to use a clamp meter that goes around the battery lead, lots of items take a while to go back to sleep when the power is restored, a clamp meter being non invasive stops the wake up and false readings. BMW i3 Electric Car
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14th May 2020 9:38am |
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ricky25 Member Since: 18 Dec 2018 Location: Leicester Posts: 17 |
Thanks for your suggestions. I was hoping to do this without disturbing the battery and losing a lot of settings as a consequence. I'm sure that before I did this from inside the car by the fusebox but can't remember how or what I'm looking for in multimeter readings !! |
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14th May 2020 10:17am |
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AJGalaxy2012 Member Since: 11 Jun 2018 Location: Gainsborough Posts: 1464 |
With the car parked up for a while, bonnet open etc, put a clampmeter around either battery lead, look at the discharge current. If it's excessive, start to pull fuses one at a time until the drain disappears, you've then found the culprit.
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14th May 2020 10:58am |
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Haylands Member Since: 04 Mar 2014 Location: East Yorkshire Posts: 8195 |
He said with a multi meter not a clamp meter, agree one of those is more ideal...
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14th May 2020 11:06am |
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AJGalaxy2012 Member Since: 11 Jun 2018 Location: Gainsborough Posts: 1464 |
The problem with a multi meter approach is that as stated the modules will wake up and be taking current for quite a while, another major problem is the power on surge is highly likely to be sufficient to blow the fuse in the meter, most multi meters max current is circa 20 amps. The Focus I looked at a couple of days ago it's power up surge was in excess of 100A recorded on the clamp meter.
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14th May 2020 11:29am |
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Haylands Member Since: 04 Mar 2014 Location: East Yorkshire Posts: 8195 |
I presumed that if he was clever enough to use a multi meter he could handle a dangerous 12v lead...... Pete
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14th May 2020 11:34am |
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AJGalaxy2012 Member Since: 11 Jun 2018 Location: Gainsborough Posts: 1464 |
Accidental touching the bodywork with the spanner on the positive terminal is the issue. Much safer to disconnect negative. BMW i3 Electric Car
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14th May 2020 11:51am |
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Haylands Member Since: 04 Mar 2014 Location: East Yorkshire Posts: 8195 |
It can't be that hard even a total idiot like me has done it hundreds if not thousands of times in the last 45 years of working on cars. I have never touched the body with a spanner that was touching a positive post and back in the day the negative one on really old cars.
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14th May 2020 12:36pm |
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stan Site Moderator Member Since: 13 Jul 2010 Location: a moderate moderated moderator moderating moderately in moderation Posts: 35287 |
its nice to see a few sparks now and again.. ... - .- -.
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14th May 2020 1:00pm |
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Joe90 Member Since: 29 Apr 2010 Location: Hampshire Posts: 6408 |
https://www.fullfatrr.com/forum/topic47332.html?highlight=drain .
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14th May 2020 1:19pm |
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AJGalaxy2012 Member Since: 11 Jun 2018 Location: Gainsborough Posts: 1464 |
No health and safety lecture, sorry you see it that way. Just because youve done it thousands of times is irrelevant really, the fact is you get it wrong once and theres a potential situation developing with no need. Whats the problem with disconnecting the negative? surely you would agree its a safer way with no penalty in terms of time or difficulty? I have no problem with anyone doing it as they please, I merely offered a suggestion to the OP that negative was a safer way. Sorry to seemingly have caused offence. AJG BMW i3 Electric Car 2012 Full Fat RR 4.4 TDV8 (now gone) 2006 VW Touareg 3.0 TDi V6 |
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14th May 2020 3:11pm |
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nicedayforit Member Since: 11 Jun 2011 Location: Beside the Solway Posts: 3973 |
No need to disconnect battery, use one of these below.
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14th May 2020 4:58pm |
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Brian Considine Member Since: 15 Apr 2019 Location: Garlinge Posts: 428 |
It may only be 12v but there is a hell of a lot of current to hand - current that can be very dangerous indeed. Many people under estimate (& come a cropper) the possible dangers & risks associated with low voltage high power electrical systems. 2003 Range Rover Vogue TD6 |
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15th May 2020 7:52am |
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