dodgethis Posted October 20, 2009 Report Share Posted October 20, 2009 Hey what the optimal voltage the battery is to be read when the car is running? I just got a multimeter and was going to check it out. Lately, the headlight have been pulsing slightly. I can drive in the day time and turn on the inside lights and can see the pulsation from the lights. I haven't seen the dummy volt light come on the dash yet. I figure I'll check the voltage on the battery, and is it also necessary to check the voltage on the alternator its putting out? I looked behind the alternator and see the positive cable, but where is the negative lead to it? Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted October 20, 2009 Report Share Posted October 20, 2009 should be about 13-14v when running. dont go by the dash. mine reads 11v on the dash but is 14v at the battery when running. there is no negative cable on the alt. just the harness and the positive Quote Link to comment Share on other sites More sharing options...
3pt1lumina Posted October 20, 2009 Report Share Posted October 20, 2009 Both of my Luminas did the same thing when the alternators were starting to go. Better to just replace it rather than get stuck somewhere...they are cheap enough. And I don't know where you will be buying your parts, but the difference between re-manufactured and new was like $20 so if it's that cheap wherever you get parts, get the new one and save yourself the hassle of a crappy rebuild. Quote Link to comment Share on other sites More sharing options...
dodgethis Posted October 20, 2009 Author Report Share Posted October 20, 2009 hey 3.1 lumina sent you a message, so guys you think gold durlast is alright at autozone? Anyone feel ac delco would be better? Quote Link to comment Share on other sites More sharing options...
3pt1lumina Posted October 20, 2009 Report Share Posted October 20, 2009 If you have an Advance Auto I'd go there, that's where I got mine... but if AZ is all you have they are okay too. I have a Duralast on my 90 and it's been on 5 yrs no problem. I replied to the PM as well. Quote Link to comment Share on other sites More sharing options...
dodgethis Posted October 20, 2009 Author Report Share Posted October 20, 2009 I just checked the battery, and the alternator with the multimeter. The battery read 12.71 volts without engine running the battery was 13.37 volts with the engine running. Quote Link to comment Share on other sites More sharing options...
AL Posted October 20, 2009 Report Share Posted October 20, 2009 That sounds fine to be honest... Rev it at 2k and check the voltage, or is that was you did Quote Link to comment Share on other sites More sharing options...
dodgethis Posted October 20, 2009 Author Report Share Posted October 20, 2009 yea im screwed. I just watched this alternator dying i'll try that al walker Quote Link to comment Share on other sites More sharing options...
tunerlover3 Posted October 20, 2009 Report Share Posted October 20, 2009 yea im screwed. I just watched this alternator dying i'll try that al walker Why are you screwed? A good mechanic can do a alternator on a 3.1 in 20 minutes. Quote Link to comment Share on other sites More sharing options...
MonteCarloDude Posted October 20, 2009 Report Share Posted October 20, 2009 yea im screwed. I just watched this alternator dying i'll try that al walker Why are you screwed? A good mechanic can do a alternator on a 3.1 in 20 minutes. Agreed, It is a very, Very easy job. Quote Link to comment Share on other sites More sharing options...
dodgethis Posted October 20, 2009 Author Report Share Posted October 20, 2009 Oh i know guys, I have read other threads about changing it out with a 3100, i am just in denial right now. The car has been great and I just like to believe it will stay that way...... Mental PHAIL! Quote Link to comment Share on other sites More sharing options...
tunerlover3 Posted October 20, 2009 Report Share Posted October 20, 2009 Sadly cars break. But then you get to fix them to make them run great. 3100 alternators are cake work. Quote Link to comment Share on other sites More sharing options...
Breakdown Posted October 20, 2009 Report Share Posted October 20, 2009 I'm going to disagree with everyone here! I had this very same thing happen and it was the battery that was on the way out. The alternator was being stressed by a battery that was never keeping a charge so instead of just powering the heater, dash lights, etc, it's trying to fill a battery that won't take a charge. I would test the battery first to see how it's doing, and eliminate it first. My interior lights did the flashing and my battery was reported as dead by all oil changers for 18 straight months, bad cell, but it finally was time to pull the plug and get a new battery. After doing so I drove the car another 30K miles and no problems, I then sold the car with a properly operating alternator. I don't think that there's any reason for alternators to die in these cars to be entirely honest which is why I'm reluctant to blame them in this instant. It's telling you something, but it might not be about itself. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted October 20, 2009 Report Share Posted October 20, 2009 ^ might have to agree with breakdown on this one.... do you have a second vehicle and a battery charger? Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted October 20, 2009 Report Share Posted October 20, 2009 all the battery does is hold a charge. if the alt is putting out 13 something volts then it is a piece of shit. Quote Link to comment Share on other sites More sharing options...
tunerlover3 Posted October 20, 2009 Report Share Posted October 20, 2009 I see alternators go out on 3x00 all the time....... Quote Link to comment Share on other sites More sharing options...
AL Posted October 20, 2009 Report Share Posted October 20, 2009 At idle, The alternator isnt moving quick enough to put out the 14V it should, but at 2k rpms, (which is where your car is alot) Its plenty fast and should have no problem putting out 14V... On my car, at idle, my battery says its only at 13.2V at idle but if I hit the throttle at all, It just to 14V easily, even with a load on it. Quote Link to comment Share on other sites More sharing options...
carkhz316 Posted October 20, 2009 Report Share Posted October 20, 2009 All my vehicles have been at least 13.8+ at idle Don't think I'm attacking anyone here, but I don't see where revving a vehicle to charge faster (in the instance of jump-starting). I've done load tests back in college during automotive class, and my puny little 3.1's 95 amp alty (rated) was able to put out nearly 100 amps at idle and still maintain 13.8 volts. (Just one vehicle example). The internal voltage regulator is always supposed to, and can, maintain that voltage pretty much no matter what, unless the alty is crappin out. Not to say there couldn't be an issue with battery or even cables. Quote Link to comment Share on other sites More sharing options...
dodgethis Posted October 20, 2009 Author Report Share Posted October 20, 2009 All my vehicles have been at least 13.8+ at idle dunno Don't think I'm attacking anyone here, but I don't see where revving a vehicle to charge faster (in the instance of jump-starting). I've done load tests back in college during automotive class, and my puny little 3.1's 95 amp alty (rated) was able to put out nearly 100 amps at idle and still maintain 13.8 volts. (Just one vehicle example). The internal voltage regulator is always supposed to, and can, maintain that voltage pretty much no matter what, unless the alty is crappin out. Not to say there couldn't be an issue with battery or even cables. Well its evident from on you tube and other that my alternator putting out 13.37 volts and the battery potential is 12.71 volts that I am below specs. I do like your thought Breakdown about the possibility of the battery "may" be going out. I think I will pull the battery out first since it will be the easiest and get it tested. If it passes then I going for the kill on the alternator. Quote Link to comment Share on other sites More sharing options...
Breakdown Posted October 21, 2009 Report Share Posted October 21, 2009 All my vehicles have been at least 13.8+ at idle dunno Don't think I'm attacking anyone here, but I don't see where revving a vehicle to charge faster (in the instance of jump-starting). I've done load tests back in college during automotive class, and my puny little 3.1's 95 amp alty (rated) was able to put out nearly 100 amps at idle and still maintain 13.8 volts. (Just one vehicle example). The internal voltage regulator is always supposed to, and can, maintain that voltage pretty much no matter what, unless the alty is crappin out. Not to say there couldn't be an issue with battery or even cables. Well its evident from on you tube and other that my alternator putting out 13.37 volts and the battery potential is 12.71 volts that I am below specs. I do like your thought Breakdown about the possibility of the battery "may" be going out. I think I will pull the battery out first since it will be the easiest and get it tested. If it passes then I going for the kill on the alternator. Aside from that, a dead or dying battery can take out an alternator (doesn't always obviously). A dying alternator cannot really hurt your battery. Quote Link to comment Share on other sites More sharing options...
carkhz316 Posted October 21, 2009 Report Share Posted October 21, 2009 ^(to add to Breakdowns post)........Unless one is lazy and just resorts to jump-starting the battery all the time, then it could sorta kill it (indirectly), due to the deep cycles. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted October 21, 2009 Report Share Posted October 21, 2009 putting out 100 amps at 13 volts will heat the alternator up hot enough to cook eggs. older alts suck for this because not only can they not disperse heat nearly as easy, but they are not really putting out RMS power. that is peak power at best. a good alt will charge at 14.9 to a dead battery. mine has hit 15.3 but its built and rated 165 amp RMS. Quote Link to comment Share on other sites More sharing options...
dodgethis Posted October 24, 2009 Author Report Share Posted October 24, 2009 Thought I give an update. So I took the battery out and took it to orieyls. They had the battery checked and it came out good. I put the battery back in the car (What a bitch) and the pulsating is gone. I took the car back over for them to check the alternator (didn't pull it off the engine) and it checked good. The cool part is they found another problem I will need to look into. The guy found arcing on one of the front spark wires ( I will do a tune up coming real soon). I figure as time goes on the pulsating will come back, which will make the bad alternator rear its ugly face. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.