robfaraway Posted December 26, 2006 Share Posted December 26, 2006 Rob fromTerrace here, using my Mum's computer, 800 miles from home (and tools!). No problems on the drive down, and no problems on Christmas Eve, driving around doing the last minute shopping. But come Christmas Day, the battery on the Loyale (93, SPFI, 5 spd) was as flat as a pancake. I got a jump start, and drove it around for about 10 minutes, and it seems to be OK. I borrowed my nephew's little analog VOM to do some basic charging checks. There is about 20 mA of current draw with everything turned off. This seems quite a reasonable number, enough to keep the memory in the radio, clock and engine management system fired up. Alternator output at fast idle is 14-15 VDC, as expected. The strange thing is there is also 30 VAC present! Do I have a diode gone? Perhaps it shorted initially and drained the battery, and now has burned out completely, so there is all that AC showing up? Any ideas would be welcome. Anyone near Coquitlam with an alternator I could borrow to test, and maybe buy? Rob. Quote Link to comment Share on other sites More sharing options...
naru Posted December 26, 2006 Share Posted December 26, 2006 You hit the nail on the head.New alt.time. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted December 26, 2006 Share Posted December 26, 2006 Any chance you left the parking lights on? The switch on top of the column.... You shouldn't be seeing the AC voltage, but sometimes with an older alt you will get a little AC current riding on top of the DC. If it's not enough to make the indicator lamps on the dash glow (brake fluid, etc) then it's probably not enough to stop you from using the alt till you can source a replacement. Your mileage may vary though GD Quote Link to comment Share on other sites More sharing options...
Loyale 2.7 Turbo Posted December 26, 2006 Share Posted December 26, 2006 Welcome! Bad Alternators can give enough Volts to the System, but without the Strenght needed (I Mean Amperes) so, your car can be Safely Driven by Day, but Battery Gone low when you Drive it by Night, due to Higher Current Consumption from the Lights... I Suggest to Check Alt. for Amperes instead of Volts, and Swap with another good one if you can; maybe from a Junk yard... Bad Alts can be Repaired too... Good Luck! Quote Link to comment Share on other sites More sharing options...
DaveT Posted December 27, 2006 Share Posted December 27, 2006 Alternator output at fast idle is 14-15 VDC, as expected. The strange thing is there is also 30 VAC present! Do I have a diode gone? Sounds like it. Time to replace the rectifier assembly. I have yet to buy an alternator. I have replaced the rectifiers, regulators, brushes, cleaned slip rings with fine sandpaper, replaced bearings. Quote Link to comment Share on other sites More sharing options...
robfaraway Posted December 27, 2006 Author Share Posted December 27, 2006 I would check the amperage output, except I have no tools available here. My good ammeter is 800 miles away, and my nephew's VOM can only handle 250mA tops. Not going to cut it here. So, the dealer should have a new rectifier assembly? Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted December 27, 2006 Share Posted December 27, 2006 Ya know, if that thing is running well enough that you think you can make it back to your tools, go shopping for one of those solar battery trickle chargers. Neat to have anyway, and might just solve your problem long enough. Dealer doesn't carry the rectifier's - they just replace entire alt's. You will have to source the rectifier through another source. But if you don't have tools to dissasemble the alternator with..... a replacement alt (hopefully with a lifetime warrantee) would probably be the best bet. Go with a parts chain you have near your home, and you'll probably be good to go. Get a small cheap set of tools to keep in the car with you too if you go that route. Best to have at least a few tools just in case - especially with older cars (of any brand). GD Quote Link to comment Share on other sites More sharing options...
Cougar Posted December 28, 2006 Share Posted December 28, 2006 I would suggest you replace the alternator with a good remanufactured unit. This way you will have all new parts in it and longer service life. I have had good service from Bosch units. One other thing to note about your AC voltage check. Some analog meters will show the DC component along with the AC voltage when measuring AC voltage. In order to block the DC voltage you need to put a capacitor in series with your test leads. Digital meters block any DC voltage in the AC voltage function so you don't see it in the reading. Quote Link to comment Share on other sites More sharing options...
robfaraway Posted December 30, 2006 Author Share Posted December 30, 2006 I got a rebuilt alternator from Burnaby Auto Parts. A great little shop, dirt cheap prices, good service. Cost was C$130. Next nearest was $180, and then over $200. He doesn't have much stock, but can get stuff in in a couple of hours. Beats heck out of Canadian Tire, who told me they could get me an alternator sometime after New Year's Day, for a whole $20 less. Works fine, and the funny noise has also gone away. I thought it might be the alternator, now I know it was. 3 phase motors make strange sounds when they lose a phase. I guess it makes sense that an alternator would too, if it loses half a phase (one diode blown). Thanks for all replies. Quote Link to comment Share on other sites More sharing options...
Cougar Posted December 30, 2006 Share Posted December 30, 2006 Thanks for the update. Glad you got it working alright for a decent price. Quote Link to comment Share on other sites More sharing options...
robm Posted January 2, 2007 Share Posted January 2, 2007 Back home again. I checked the AC output of the new alternator with a decent Fluke DMM. Essentially zero VAC at the battery terminals. So even if the little analog meter I used to measure the output of the old alternator was seeing DC as well, there was a good 15 VAC on the output. A good way to test for bad diodes. Quote Link to comment Share on other sites More sharing options...
daeron Posted January 3, 2007 Share Posted January 3, 2007 Sounds like it. Time to replace the rectifier assembly. I have yet to buy an alternator. I have replaced the rectifiers, regulators, brushes, cleaned slip rings with fine sandpaper, replaced bearings. Youre the BOMB!! why replace what you can rebuild? I am ecstatic to have finally found a good auto electrical place right down the street from my house. the ONLY guy left in town who still sells all that crap, is less than 2 miles from my house. a bike ride away Quote Link to comment Share on other sites More sharing options...
jimbo79 Posted August 20, 2007 Share Posted August 20, 2007 Any chance you left the parking lights on? The switch on top of the column.... You shouldn't be seeing the AC voltage, but sometimes with an older alt you will get a little AC current riding on top of the DC. If it's not enough to make the indicator lamps on the dash glow (brake fluid, etc) then it's probably not enough to stop you from using the alt till you can source a replacement. Your mileage may vary though GD I have a charging problem. The Alt light is on. Voltage is low. however,headlights burn bright. The stop lamp and brake fluid lights are dimly lit. Battery drains over night. any suggestions? Quote Link to comment Share on other sites More sharing options...
Gloyale Posted August 20, 2007 Share Posted August 20, 2007 I have a charging problem. The Alt light is on. Voltage is low. however,headlights burn bright. The stop lamp and brake fluid lights are dimly lit. Battery drains over night. any suggestions? Sounds like you need a new alternator. The Charge,Brake and Stop lamp lights coming on dim is a sure sign that you are not charging. Check to make sure the large wire that attaches to the post on the alternator is not corroded and that it has a good connector on it. But, if that is all OK then you have a bad alternator. Have you're battery charged and tested before you install a new Alt. You're old Alt has been overtaxing the Batt, and may have put it on it's last legs. Unless Batt charges and tests near 100%, I would suggest replacing it as well when you do the Alt. Quote Link to comment Share on other sites More sharing options...
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