samneric Posted October 17, 2010 Share Posted October 17, 2010 (edited) While out last night. Turned the key - nothing. Not even a light on the dash. Battery die in like 3 hours while I was away???? I've never seen such strange circumstances - usually battery loses power over a period of journeys. Noticed the volt meter was hovering up slightly above the halfway line a few days ago but didn't get near red. Bad alt??? This is like the 3rd alt that I've put in there - the last just 2 months ago - this is getting expensive in alternators :-\ Steve Edited October 18, 2010 by samneric Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted October 17, 2010 Share Posted October 17, 2010 A few possibilities: 1. There is a voltage drop on the VR sensor line between the back of the alt and the main junction or between the main output lug on the alt and the main junction - this will cause the alt to pump the voltage up higher to compensate for what it thinks is heavy circuit draw..... 2. You are putting the belt on too tight and borking the bearings. It need only be tight enough not to slip - if it's old and hard that means it will have to be *too tight* for the longevity of the bearings so it's best to replace the belt and have nice soft rubber and keep it as loose as it will allow. 3. You are working the alt too hard - you have too many circuits drawing too many amps. In which case you need a larger alt and added wireing to compensate. 4. You are buying cheap reman alts and they are simply junk. GD Quote Link to comment Share on other sites More sharing options...
samneric Posted October 17, 2010 Author Share Posted October 17, 2010 A few possibilities: 1. There is a voltage drop on the VR sensor line between the back of the alt and the main junction or between the main output lug on the alt and the main junction - this will cause the alt to pump the voltage up higher to compensate for what it thinks is heavy circuit draw..... 2. You are putting the belt on too tight and borking the bearings. It need only be tight enough not to slip - if it's old and hard that means it will have to be *too tight* for the longevity of the bearings so it's best to replace the belt and have nice soft rubber and keep it as loose as it will allow. 3. You are working the alt too hard - you have too many circuits drawing too many amps. In which case you need a larger alt and added wireing to compensate. 4. You are buying cheap reman alts and they are simply junk. GD 4) - I usually buy the most expensive ones I can find at napa - prob not this one 3) I thought my amp was doing this so I disconnected it last time the alt went. Maybe something else in the circuit is bad and shorting causing load???? 2) I may be borking the bearings. I always thought I had to get it as tight as I could 1) VR Sensor line - is that in the alt? How to test for this??? Steve Quote Link to comment Share on other sites More sharing options...
edrach Posted October 17, 2010 Share Posted October 17, 2010 You may have a blown fusible link. Check for that first. After you recharge the battery, first determine whether you have an actual draw on the battery. Unhook the negative cable from the battery and use a multimeter to determine how much current draw you have with the ignition off; anything more than 1/4 amp is suspect. If your battery died in three hours, it would have to be more than a ten amp draw and should be pretty easy to find. If you find no excessive current draw, then start investigating the alternator or battery since one or the other is probably very bad. Quote Link to comment Share on other sites More sharing options...
phantomD Posted October 17, 2010 Share Posted October 17, 2010 Has the same battery suffered all of your bad alternators? Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted October 17, 2010 Share Posted October 17, 2010 (edited) Yes you should definitely check out your battery and the current draw while the car is off as Ed noted - a bad battery can make the alt work very hard (the battery is the only device in the system that WILL pull every amp the alternator can make for extended periods), and a draw while the ignition is off will drain the battery and make the alt work hard at every startup to replenish what has been lost. I like the Bosch reman's. I've had good luck with them myself both on EA's and EJ's and even with the Maxima alts. I actually have not had one fail yet and I have three - two of which are used from the junk yard To test the VR sensor line and the output line, you simple run a DC voltage test (engine running) with your meter between the output lug and sense terminal on the alt and the main junction (positive side of the fusible links). You should see very little voltage drop across that run - 0.25 VDC or less. It's somewhat misleading how they have it wired from the factory - the sense line is only about 12" long and is crimped back into the the output line just downstream of the alt..... so if you have a big drop on one and not the other then the problem is at or near the alternator. If you have a problem on both then the problem is likely over near the fusible link box. EA81's are especially prone to this type of failure as the battery is way over on the other side of the engine bay with that wireing running down along the lower radiator core support near the ground and road salt, etc. With the EA82 and up they moved it to the other side so the run from the alt to the main junction is very short and you don't see this type of failure. Since you have a stereo, etc - you might want to install an actual "amperage gauge" - for those that know how to read them these are much more helpful than a voltage gauge. Ideally you should have both, but there's a reason cars used to have "charge gauges" (amp gauge) - the reason is two-fold - first because older stuff had generators and they wouldn't charge much (if at all) at idle. And second - the man of the house used to understand how to read one and what it meant GD Edited October 17, 2010 by GeneralDisorder Quote Link to comment Share on other sites More sharing options...
samneric Posted October 18, 2010 Author Share Posted October 18, 2010 You may have a blown fusible link. Check for that first. After you recharge the battery, first determine whether you have an actual draw on the battery. Unhook the negative cable from the battery and use a multimeter to determine how much current draw you have with the ignition off; anything more than 1/4 amp is suspect. If your battery died in three hours, it would have to be more than a ten amp draw and should be pretty easy to find. If you find no excessive current draw, then start investigating the alternator or battery since one or the other is probably very bad. Aha! forgot about those links ..... Just had it towed home..... The first AAA guy did a batt test ans said that was OK.... we checked and replaced a blown Batt fuse (15a) but still dead.... fusable link - rings a bell - must have gone... But what caused it..... will read and try all options presented in the thread when I have daylight and tools handy - thanks all... Steve Quote Link to comment Share on other sites More sharing options...
samneric Posted October 18, 2010 Author Share Posted October 18, 2010 Do you know what it was after all that???? The damn cable from the battery to the fusible link box came unplugged Must have been all those times I took the battery out to have it recharged when the alt died last time. Wiggled lose over time. The volt gauge is hovering around or slightly half way so I guess this is just higher until the battery is recharged from the start... I will keep my eye on it. Still, at least I don't have to spring for a new alt this time Steve Quote Link to comment Share on other sites More sharing options...
NoahDL88 Posted October 18, 2010 Share Posted October 18, 2010 Good deal, I always try to check the easy and cheap stuff first, fuses, connections and switches. Its pretty amazing how many cars won't start simply because of a corroded terminal or a bad connection. Quote Link to comment Share on other sites More sharing options...
edrach Posted October 18, 2010 Share Posted October 18, 2010 I think that cable is tied to the battery and the alternator output. I imagine if the cable shorted to ground while the engine was running it would toast your alternator real easily. Glad to hear it was simple. I'm a firm believer in the KISS theory: Keep It Simple Stupid! Quote Link to comment Share on other sites More sharing options...
samneric Posted October 18, 2010 Author Share Posted October 18, 2010 I think that cable is tied to the battery and the alternator output. I imagine if the cable shorted to ground while the engine was running it would toast your alternator real easily. Glad to hear it was simple. I'm a firm believer in the KISS theory: Keep It Simple Stupid! Good thing that cable has a plastic plug on it then Yeah, my PE teacher from high school taught is all the Principle of KISS Steve Quote Link to comment Share on other sites More sharing options...
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