itsbrokenagain Posted January 31, 2011 Report Posted January 31, 2011 Hi Everyone,I'm new to the forum, but have been 'dipping in' over the past few months and have found it to be very informative. Anyhow, I have a problem with the battery being drained if left connected for any lengthy period of time eg, overnight.The battery itself is fine. ie, it receives and holds a charge ok. Has anyone come across this problem and is it likely be linked to the wires in the driver door gaiter as i have an intermittent(mind of it's own) window. I did a quick search on the forum but couldn't find this specific problem,so excuse me if I missed an explanation/description of the solution to this. Thanks in advance Quote
Mirez Posted January 31, 2011 Report Posted January 31, 2011 The problem you have it that there are hundreds of wiring systems on a modern car that could be the cause. You need to identify which circuit is draining the current to start with, do you have a volt meter? I can guide you through the basics of current checking if you have a basic knowledge of electrical stuff. Dont leave it long, car batteries arn't designed to be run flat and it won't take that many of them to ruin your battery. Quote
edatelder Posted January 31, 2011 Report Posted January 31, 2011 Is everything turned off at night? Try one night to disconnect the battery (hope you know the radio code)and reconnect it in the morning, set the clock too. If all is well it's a wiring fault, if it fails to start it's a battery fault. Quote
itsbrokenagain Posted January 31, 2011 Author Report Posted January 31, 2011 The problem you have it that there are hundreds of wiring systems on a modern car that could be the cause. You need to identify which circuit is draining the current to start with, do you have a volt meter? I can guide you through the basics of current checking if you have a basic knowledge of electrical stuff. Dont leave it long, car batteries arn't designed to be run flat and it won't take that many of them to ruin your battery. Thanks for quick responses.....Mirez,edatelder Yes i do have access to a tester and a little basic understanding.At the moment I am disconnecting the battery every time I leave the car!Mirez,A walk through guide to try and isolate the problem circuit would be great. Quote
Mirez Posted January 31, 2011 Report Posted January 31, 2011 (edited) Ok well the first thing you need to do it get an idea of what current is being drawn, since you are disconnecting the battery already then its easy to do :) We are going to measure current here not voltage so you'll need to change the probes so the black is in the COM socket of the tester and the red is in the 10ADC socket (name changes but most testers will have 10A Max on that socket). Put the meter in the "current" mode, again it normally says 10A. 10Amp isn't that much so keep the doors closed and dont use any electrical circuit while you do this. You now need to connect the meter in series with the battery so put the black probe on the batteries + terminal and the red probe on the disconnected clamp - you basically want to complete the circuit using the volt meter and because of this you may get a little spark as you connect it.. The reading you get here will be the current draw, let it settle for a few minutes so you get a non fluctuating reading and then write this value down. Typically in an "off" state you would expect a current draw of less then 200ma and that's an upper limit - I suspect its gonna be higher then that given its flattening the battery overnight. You now need to find where that draw is going. If you have a Mk2 then you'll have the mini fuse box infront of the battery - undo the bolt for the first 100A fuse and connect the meter in series again here - reconnect the main battery clamp and check what you have here, from memory the 1st is the alternator and the second is the main feed to the cabin. Go through them all and hopefully you'll find one that matches the draw - what you don't want here is for the current to be splitting as it indicates you have more then one problem. I would suspect that you'll find the draw is being passed into the cabin as thats got the most number of individual circuits connected to it. If you've followed to this point then you've worked out which section of car is drawing the current. We can now narrow down further. You'll need to open the door now so disconnect again and turn off all the interior lights - you want the door open but the car to be "as off" so ideally remove the lamps you can't turn off such as footwell and tailgate ones. If you can't do that you'll need to calculate the additional current draw and subtract that from our figure. Now reconnect the meter in series (between the battery and clamp) and get someone to monitor the reading - you now need to disconnect and reconnect each fuse in turn whilst watching for significant change - when the reading significantly lowers you'll know which circuit is drawing the current. Remember as you reinsert the fuse that circuit will go live again and may draw some current so you'll have to wait for the reading to settle down again. Post back the result and we can help diagnose where the most likely cause will be. Finally remember to put the probes back into the Vma socket else you'll get a nasty suprise when you next try and read a voltage :) Edited January 31, 2011 by Mirez Quote
itsbrokenagain Posted February 1, 2011 Author Report Posted February 1, 2011 Thanks for guide/info.I will give it a go in the next day or so and post results. Cheers Quote
dbc Posted February 1, 2011 Report Posted February 1, 2011 This post is extremely useful for any one trying to fault find electrical issue. Should be stuck in the useful section. Good job mirez Quote
itsbrokenagain Posted February 2, 2011 Author Report Posted February 2, 2011 Hi all. Once again,thanks for excellent walk through guide! Unfortunately,I didn't have current testing ability on my Fluke 110 multimeter, so I have ordered a cheapy off '-bay watch' due to arrive at the end of the week. Anyway,while cleaning out the car,I heard a sound,wires shorting, coming from the offside passenger door(the rubber boot for the wiring). On inspection i found several of the wires (brown,red,green)were broken and touching ones they weren't meant to. (also, the driver's window has opened and is determined to stay that way! B*LL*CKS) You know what's coming..... Another question ......! How likely is it that the short in the door(s)is causing the battery drain. (or is this to good to be the case.) Cheers Quote
Mirez Posted February 2, 2011 Report Posted February 2, 2011 Highly likely, there is 12V there most of the time even with the ignition off - I would suspect the central locking circuits been shorting to the electric window motor which will draw a good couple of amps (and flatten a battery overnight) but could also have drastically reduced the life of the motor and hence why you now have window trouble :( (although that could also be down to the wiring shorting out) Quote
itsbrokenagain Posted February 3, 2011 Author Report Posted February 3, 2011 It gets even better..........! I checked the other door gaiters, and guess what.....?...yup....(every one's a winner) they ALL have broken wires. I 'disconnected' all the passenger doors and 'jiggled' around with the drivers one and up went the open window...also found a pound coin in the footwell......double result! Gonna get stuck in to the repairs using the faqs section on the w/end. (and buy myself a pack of winegums to celebrate) Will post outcome soon as. Thanks Quote
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