momo Posted April 25, 2013 Report Share Posted April 25, 2013 (edited) Morning folks! My car has developed an odd battery light problem.. Usually when cold (so 1st thing in the morning on the way into work) occasionally the red battery light pops up. Only ever comes on for a split second or a second at the most then goes out. Initially thought it was related to the engine revs as I kept noticing it when for example changing gear or slowing for a junction etc.. However this morning kept a closer eye on it, it also came on as I was accelerating so as the revs increased. So i'm ruling out ignition related problems. Car runs absolutely bang on otherwise! My Alternator failed and was replaced in Mid-2010 so I hope it's not that! Battery though (I assume) is original to the car.. I've not changed it since I bought the car in 2008 and I don't think it was changed before then.. Anyway my question is this: 1) Anyone had anything similar? 2) How can I test the battery/alternator with a multimeter? And what voltages should I be looking for? 3) If a replacement battery is needed, where's the best/cheapest place (for a quality battery mind) to get one? I'd rather not have to get an Alternator again so want to test it properly 1st as last time the cheapest I could find was about £250!! But if it IS then I want to be 100% sure! Thanks in advance folks! Edited June 23, 2013 by momo Link to comment Share on other sites More sharing options...
mit Posted April 25, 2013 Report Share Posted April 25, 2013 Probably your battery on its way out Link to comment Share on other sites More sharing options...
momo Posted April 25, 2013 Author Report Share Posted April 25, 2013 Yeah pretty sure it is Mit, just need to know how to test it properly before I buy one. As it stands, will probably buy one from BMW to make sure its the right one.. Link to comment Share on other sites More sharing options...
mit Posted April 25, 2013 Report Share Posted April 25, 2013 There's a decent online battery shop... very reasonable pricing: http://www.battery2u.co.uk/3-SERIES-E46-325i-3281I-330I-M3-CABRIOLET-Petrol-99-/ Bosch battery is about £120 from BMW I think. These ones are cheaper than Halfords own brand! momo 1 Link to comment Share on other sites More sharing options...
TriggerFish Posted April 25, 2013 Report Share Posted April 25, 2013 There's a test for the battery in the hidden OBC menus. http://www.sal-e.net/node/147 Test 9. Not sure if it shows want you need or not though. momo 1 Link to comment Share on other sites More sharing options...
momo Posted April 25, 2013 Author Report Share Posted April 25, 2013 Hmmm.. It says my car should have the same battery as a 323??? That makes no sense? Diesel batteries are normally bigger and seen as though it's a 3.0ltr is should be WAY bigger than a 323.. Will double-check on mine but from other websites say I need something around the 100Ah mark.. Not the ~70Ah mark.. Link to comment Share on other sites More sharing options...
simonlpearce Posted April 25, 2013 Report Share Posted April 25, 2013 Is the battery secured and all connections nice and tight? Link to comment Share on other sites More sharing options...
momo Posted April 25, 2013 Author Report Share Posted April 25, 2013 There's a test for the battery in the hidden OBC menus. http://www.sal-e.net/node/147 Test 9. Not sure if it shows want you need or not though. Thanks mate! I want to test mine properly with a multimeter though.. I want to rule out sensor issues etc too so would rather do it from the battery itself. Si - pretty sure it is! Last time I touched it was when I fit my steering wheel in 2011 so couldv'e worked loose I suppose? TriggerFish 1 Link to comment Share on other sites More sharing options...
R2D2 Posted April 25, 2013 Report Share Posted April 25, 2013 You wont be able to fully test your battery with just a multimeter as youll need to load test it to check its retaining a 12V rail when current is being drawn from it. You can test your alternator with just a multimeter though. Your battery terminals should read 13.5-14V with the engine ticking over if the alternators ok. If you do the above as well as get your battery load tested at a garage and all is fine, then It might also be worth checking the wiring on the alternator. On one of my previous cars the 12V terminal on the alternator was very loose. Link to comment Share on other sites More sharing options...
momo Posted April 25, 2013 Author Report Share Posted April 25, 2013 Might have to get it tested from a garage to be completely sure as you say R2D2.. Link to comment Share on other sites More sharing options...
mit Posted April 25, 2013 Report Share Posted April 25, 2013 (edited) Hmmm.. It says my car should have the same battery as a 323??? That makes no sense? Diesel batteries are normally bigger and seen as though it's a 3.0ltr is should be WAY bigger than a 323.. Will double-check on mine but from other websites say I need something around the 100Ah mark.. Not the ~70Ah mark.. I would say your logic makes no sense here. Why should a 330 need a higher battery capacity than a 323? It takes almost the same energy to crank both engines and fire the same number of cylinders from cold... the electrical requirements shouldn't be very different... Edited April 25, 2013 by mit Link to comment Share on other sites More sharing options...
momo Posted April 25, 2013 Author Report Share Posted April 25, 2013 Other way around.. 330 should be bigger than 323. It's because the engine is begger/heavier so requires more ooomph to crank it? At least thats my logic.. Link to comment Share on other sites More sharing options...
R2D2 Posted April 25, 2013 Report Share Posted April 25, 2013 Other way around.. 330 should be bigger than 323. It's because the engine is begger/heavier so requires more ooomph to crank it? At least thats my logic.. The engine is bigger cylinder bore-wise, but im not sure that makes it physically any bigger/heavier as theyre both 6 pot engines iirc? Link to comment Share on other sites More sharing options...
B0B Posted April 25, 2013 Report Share Posted April 25, 2013 The engine is bigger cylinder bore-wise, but im not sure that makes it physically any bigger/heavier as theyre both 6 pot engines iirc? No the bore is the same, the 330's have a longer stroke though Link to comment Share on other sites More sharing options...
momo Posted April 25, 2013 Author Report Share Posted April 25, 2013 I know the dry weight of a 330i is less than the 330d.. If the only difference is the engine then surely this has to be down to the weight of the engine? 330i - http://www.parkers.co.uk/cars/reviews/facts-and-figures/bmw/3-series/saloon-1998/21798/ - 1505Kg 330d - http://www.parkers.co.uk/cars/reviews/facts-and-figures/bmw/3-series/saloon-1998/24649/ - 1615Kg If so, then surely it needs a bigger battery? I know the diesel needs a bigger alternator.. Mine needed a 150A alternator.. Link to comment Share on other sites More sharing options...
B0B Posted April 25, 2013 Report Share Posted April 25, 2013 Surely it would be down to compression ratios which would need the heavier duty battery? Link to comment Share on other sites More sharing options...
momo Posted April 25, 2013 Author Report Share Posted April 25, 2013 More than likely - i'm happy to say i've got NO idea! I'm just guessing but atm it makes a little sense in my mind so i'll stick with it! Plug bigger is always better! Link to comment Share on other sites More sharing options...
momo Posted April 25, 2013 Author Report Share Posted April 25, 2013 Just been for lunch and noticed something - the battery light didn't come on at all! I reckon with the car sat overnight, the alarm etc.. draining the battery it causes the light to come on when it's not fully charged in the morning. BUT once i've driven it during the day it doesn't come on again as the alternator charges the battery.. Think it makes sense? I think it does.. I'll get it tested properly to confirm.. Link to comment Share on other sites More sharing options...
mit Posted April 25, 2013 Report Share Posted April 25, 2013 Other way around.. 330 should be bigger than 323. It's because the engine is begger/heavier so requires more ooomph to crank it? At least thats my logic.. Sorry that was a typo... why should a 330 need a higher capacity than a 323 etc etc (as per what I typed).. Link to comment Share on other sites More sharing options...
mit Posted April 25, 2013 Report Share Posted April 25, 2013 I know the dry weight of a 330i is less than the 330d.. If the only difference is the engine then surely this has to be down to the weight of the engine? 330i - http://www.parkers.co.uk/cars/reviews/facts-and-figures/bmw/3-series/saloon-1998/21798/ - 1505Kg 330d - http://www.parkers.co.uk/cars/reviews/facts-and-figures/bmw/3-series/saloon-1998/24649/ - 1615Kg If so, then surely it needs a bigger battery? I know the diesel needs a bigger alternator.. Mine needed a 150A alternator.. No because the cylinder block is the bit that's heavier, not the pistons and crankshaft. Iron vs aluminium I expect, for the higher compression. And the turbo and intercooler probably weighs something. R2D2 and momo 2 Link to comment Share on other sites More sharing options...
R2D2 Posted April 25, 2013 Report Share Posted April 25, 2013 No because the cylinder block is the bit that's heavier, not the pistons and crankshaft. Iron vs aluminium I expect, for the higher compression. And the turbo and intercooler probably weighs something. Ah yes, ive got a feeling youre right there. Have a biscuit. Link to comment Share on other sites More sharing options...
mit Posted April 25, 2013 Report Share Posted April 25, 2013 Ah yes, ive got a feeling youre right there. Have a biscuit. Thanks! What kind of biscuit? Link to comment Share on other sites More sharing options...
momo Posted April 25, 2013 Author Report Share Posted April 25, 2013 This one? mit 1 Link to comment Share on other sites More sharing options...
momo Posted June 23, 2013 Author Report Share Posted June 23, 2013 Ok guys, still not replaced the battery yet (CBA being the main reason.. lol) BUT.. I think the time has come now.. Was driving to work after lunch on Friday, had the music a little louder than usual and instead of the light just popping on for a split second, it stayed on for more like 4-5 seconds at a time.. lol. I think it's about to stop working all together. lol. So alas, the time has come! Anyone know where the best place to get a battery is? For ~£120 I don't really mind going to BMW tbh.. It lasted almost 10years so I think that's pretty good value for money considering I may well keep this car for a long time yet! BUT - at the same time I don't want to get ripped off.. TIA Link to comment Share on other sites More sharing options...
momo Posted June 23, 2013 Author Report Share Posted June 23, 2013 Anyone? Link to comment Share on other sites More sharing options...
