LoudBimmer Posted October 2, 2013 Author Report Share Posted October 2, 2013 well, when a window motor starts (any electric motor for that matter) you'll get a surge as the motor starts. Not to mention that I'm sure that the BMW didn't go overkill on the normal internal wiring... Can you measure at the alt and verify? Already checked it few times. I don't want to risk amplifier to see If I will have voltage drop if I put one in. just because you're at 2k rpm you're alternator isn't always supplying 260a like you said....only when needed I thought? That's what I'm trying to clarify. Link to comment Share on other sites More sharing options...
Wicks Posted October 2, 2013 Report Share Posted October 2, 2013 You're seeing voltage drop all at the cig lighter, alternator and the back battery? Voltage drop at the cig lighter is probable as its wiring and that going to the window is most likely minimal. A normal user isn't going to notice or care about a lost volt when they use their windows. I wouldn't expect to see any voltage drop though at the alt or the battery, especially at 2k rpm. Everything I've researched on my car says that there is no PCM on the alternator, its always on. I wasn't able to test it much though as I went straight to a HO Mechman with an external Vreg. This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
LoudBimmer Posted October 2, 2013 Author Report Share Posted October 2, 2013 with the 260A alternator and D3100 battery, I really don't expect a single volt drop. I'm really running out of options right now. I was thinking about going with Mechman, but there is no guarantee that it will work. At this point I don't even know what to check. Link to comment Share on other sites More sharing options...
dangaranga Posted October 2, 2013 Report Share Posted October 2, 2013 You could go to a parts store and have them put their tester on it, with the H.O alt theoretically the voltage shouldn't drop a ton but it's just a thought, or find a buddy that has one of those 100 amp hand held battery testers to put a load on the alt and watch the voltage Brandon 2000 Furd Ranger supercab 4x4 System: welding wire throughout the truck USalts 390amp Hairpin Juicebox in stock location 8 Banks of maxwell supercaps 2 American Bass Vfl 1100.1 wired to .35 each 2 Fi Audio Sp4 18's ( the DD sc 9918's smoked) Pioneer radio with Soundstream PA mids Powered by a nice sized soundstream 2 channel It's pronounced (dain-ja rain-ja) 2001 2 door focus 1 DD9918 SC Link to comment Share on other sites More sharing options...
David Bailey Posted October 2, 2013 Report Share Posted October 2, 2013 When you have everything on (a/c, radio,light) and use the window, does it just drop to 13.4, or has it dropped lower? Maybe that is as low as the ECM will let it drop, and in that case, you should be good. Even if you add an amp, it might not go lower since you have the electrical beefed up. I wouldn't worry unless it dropped into the 12s. Did you get that scar tissue when you got your vagina installed? KNOWLEDGE DESTROYS FEAR Measure twice, cut once JVC touchscreen HU Mmats E600.4 Realm L56c Audiophile 6.5 comps up front JBL P963 rear deck PB RTA 112 trunk CE Auto Big 3 Mechman 240alt D'Amore VM-1 Link to comment Share on other sites More sharing options...
Wicks Posted October 2, 2013 Report Share Posted October 2, 2013 So you are seeing voltage drop at both the alternator and the back battery by just using the window?? If so you have faulty equipment or a bad / corroded connection that is causing system-wide voltage drop. With an HO alt and a big battery, power windows should not affect your overall voltage. Now if you're checking voltage at one of the window motors then it could have some drop there due to smaller factory wiring. This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
LoudBimmer Posted October 3, 2013 Author Report Share Posted October 3, 2013 It would make sense to see a quick voltage drop due to the stock electrical being small ( 16gauge wire). I will re-check voltage at alternator and in the back where battery is with 0gauge wire run. One other thing, so does alternator put out 260A@2k rpms? Constant 260A to the battery or only when it requires the 260A?? Link to comment Share on other sites More sharing options...
Quiet Posted October 3, 2013 Report Share Posted October 3, 2013 The draw has to be there for the output to be supplied. With everything off, there's infinite resistance and nothing to pull current. At 2k RPM, the current should be available but just needs something to draw it. 2007 Pacifica Rebuild. Less quiet. Still not loud. Link to comment Share on other sites More sharing options...
LoudBimmer Posted October 3, 2013 Author Report Share Posted October 3, 2013 So when the current is drawn at 2k rpm, the alternator becomes more resistant( harder to spin) and that's when belt slip happens? Link to comment Share on other sites More sharing options...
SnowDrifter Posted October 3, 2013 Report Share Posted October 3, 2013 Positive probe to your alt charging post, negative probe to alt casing. Then measure your voltage drop with a multi meter. Throw an amp in there, put a non-stock load on it and see how the alt reacts. Who makes your alt? ~~~~~~~~SAY NO TO PHOTOBUCKET~~~~~~~~ Snow's DD-1 tracks here: https://www.stevemeadedesigns.com/board/topic/167433-snows-dd-1-tracks/ My take on OFC vs CCA: https://www.stevemeadedesigns.com/board/topic/110381-things-that-piss-you-off-in-the-car-audio-world/?do=findComment&comment=2461444 Link to comment Share on other sites More sharing options...
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