euroriffic 603 Report post Posted April 18, 2013 (edited) So I took the M3 for a drive this evening to look at a perky. I made a stop to get gas, went to the job for about 10mins. Left, then went for a blast on one of our great roads from portabello up over highcliff road then back home- about a 45min non stop drive. Just as I was pulling into my street the airbag light came on. Then as I was reversing up my drive I managed to stall it then went to restart but wouldn't as for some reason the battery was dead so had to roll start it. Once I got it into the garage the abs light was now on aswell so turned the car off and tried to restart but just got clicking of the starter. The car has only been going since last week and I had the battery on the charger untill it went back into it so was fully charged. And when I started the car the 3 times tonight there was no sign of it struggling to turn it over from a flat battery either so why has it all of a sudden just lost all power even though it should of being charged while it was running? Anyone else had this happen to them? Guess I'm getting a new battery this weekend Edited April 28, 2013 by euroriffic Quote Share this post Link to post Share on other sites
swordfish 30 Report post Posted April 18, 2013 Sounds exactly what I had when my alternator cracked up!!! I mean pretty much what happened to me! Check you alternator terminals and then do a voltmeter check. Before you buy a new battery. Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 19, 2013 I thought it might of been the alternator but the charging light should of come on and when I roll started it shouldn't of worked as the alt woundnt of being making any power. Will do some investigating tomorrow. Quote Share this post Link to post Share on other sites
Ahmedsinc 414 Report post Posted April 19, 2013 Bit of a long shot, but have you had a good look at your earthing points? Had a similar issue with a Toyota a few years back that turned out to be a bad earth from the - post Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 19, 2013 Ahhhh yes, had that before too. Will give it a good look over tomorrow before I go getting a new battery. Quote Share this post Link to post Share on other sites
Ahmedsinc 414 Report post Posted April 19, 2013 I'm no auto sparkie but it's worth a look Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 21, 2013 Got it sorted yesterday, was luckily just the battery had sh*t a cell causing all the issues so now has a new battery and is good as gold again. Quote Share this post Link to post Share on other sites
swordfish 30 Report post Posted April 21, 2013 Got it sorted yesterday, was luckily just the battery had sh*t a cell causing all the issues so now has a new battery and is good as gold again. What brand did you go for? and what model? i am looking at a new battery as well... Winter is coming and takes the last juices out of my old poor battery. Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 21, 2013 best I could find was a century maintainace free 520cca european spec one at suoercheep. Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 28, 2013 Ok, so its just happened again. Was driving along, radio went off, airbag and abs light came on, all interior lighting was dimmed but motor kept running. Almost seems like the accessories are running from the battery draining it but the motor is still powered by the alternator. Is there a relay or something that can cut the connection from the alternator to the battery to stop it charging? Quote Share this post Link to post Share on other sites
Ahmedsinc 414 Report post Posted April 28, 2013 Sorry dude, my usefulness ceases at earthing. Wonder if Jochen or Hotwire still check in, this sounds like a puzzle for those two Quote Share this post Link to post Share on other sites
kiwi535 538 Report post Posted April 28, 2013 is it the FUSIBLE LINK? Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 28, 2013 Fusible link you say... Quote Share this post Link to post Share on other sites
hotwire 352 Report post Posted April 28, 2013 My suggestion is to get it checked by a sparky - initially scan the circuits. Could be for one of several reasons & easier to diagnose the car than try to explain all the varialbles /checks Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 28, 2013 I'm a sparky by trade... just not an auto one, but have a pretty good knowledge of dc supplies and circuits. Will get the battery charged and do some more investigating. Will get a scan and live data on it if I can't find anything. Quote Share this post Link to post Share on other sites
hotwire 352 Report post Posted April 28, 2013 Ok, check plug connections on ign switch & input/output voltages. Main supplies/earths Get the ABS & Air Bag circuits scanned Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 28, 2013 Abs and airbag are just due low voltage, soon as a good battery is on it it goes away. Been lookng at afew diagrams and I'm thinking there's a dodgey connection somewhere thats dropping out the alternator to the battery, leaving the engine to run the essentials and the battery to do the accessories which inturn is draining it after half an hour of driving. Will be taking a good look tomorrow with a good battery and ith the car running. Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 29, 2013 So got the old girl fired up tonight, checked the battery while running, 14v. Turned on lights and heaters, checked again, 12.28v. Raised revs to 2000, 12.18v. Turned everything off, 12.28v So I've come to the conclusion the voltage regulator has gone on it as it will charge untill load is put on it, meaning alternator stator/armature are still working fine. Now I just need a new regulator... Quote Share this post Link to post Share on other sites
hotwire 352 Report post Posted April 29, 2013 Likely the regulator but not necessarily. Have you checked the fan belt not loose/slipping? - will cause that symtom. Could also be a phase out in the stator/rectifier circuit. Also make sure you have no voltage drop on the battery supply to the alt. Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 29, 2013 Belt was good and voltage was the same from the back of alternator and battery. Quote Share this post Link to post Share on other sites
Etwenty1 45 Report post Posted April 29, 2013 (edited) Belt was good and voltage was the same from the back of alternator and battery. I reckon its your alternator anyway - output should be around 14.5v unloaded IMHO. Have you checked the alt brushes on the reg? take it off an measure them, can't remember the spec but it'll be on the web somewhere. But the voltage drop when you rev it suggests the stator has a bad leg = new alt You also need to be checking the current as well which is outside what most diy DMM's can measure. A good auto sparky will be able to bench test and advise. Unless its you daily whip it out and take it in for testing so you are not "stuck" at the auto-sparky when he gives you the price to replace it.... maybe not the same place that sold you the new battery.......still have it? Edited April 29, 2013 by etwenty1 Quote Share this post Link to post Share on other sites
euroriffic 603 Report post Posted April 30, 2013 tried to fit two replacement alternators today, one a bosch 140a and a valeo 80a. both would of bolted up fine but the connectings and air intake were in different places so wouldnt of worked. also swapped the reg over from the 80a to my alt but made no difference. best to just buy a new one. be about the same to get it looked at and fixed proberbly. got the battery at supercheep but the missus car is needing a new battery so she can have the old one Quote Share this post Link to post Share on other sites
