Voltage issue, in drive under load, or regular road speed 13 -13.5 volts, at a stoplight/stopped and still in drive but on brakes, 9-9.5 volts. In neutral, 13-13.5 volts, as soon as car goes in gear drops back to 9-9.5 volts, until speed is picked up, then at 13-13.5 volts, Battery slowly getting weaker. Car in park, no load 13-13.5 volts, lights on 9 volts or weaker Like the battery isnt being recharged, by the alternator. Tested alternator on car, good. Took off car and to alternator rebuild shop, completely checked out all good. Checked/tested battery on car, weak and in need of charge, but good. Checked/tested battery off car still the same, weak in need of charge but good. Charged battery over night, checked off car, good. back in car same issues. Replaced battery to starter cable with new, replaced battery with another, same issues. No exterior voltage regulator, alternator has internal regulator , all checks out good. Everything off and unplug,(car stereo, electric fans) only basic electronics and still the same, What else could there be? Considering running a direct 12g line from back of alternator to battery pos. and then testing , will this even work ?
internal or external regulator? whats the idle speed below 800 or so yor gonna have that if its a one wire thats how they work. change it to a three wire. jim
Which internaly regulated alternator do you have? 10/12 SI or CS? The 10/12 SI has a dide trio that can cause your problem if shorted or open.Also with charged battery,no accesorys on @ fast idle you should be over 14V.
How old is your battery? The condition you are seeing is usually caused by a faulty battery. The alternator charges it as best it can but at low engine speed or under load it can not keep up with the charging and load. The battery can take a bit of a charge and show ok if you are testing it with only a volt meter. If the battery was load tested and still showed good the problem could be the alternator.
Did a full over night battery charge,dropped off at advance,next day picked up,tested before leaveing store and check showed, all good,same issue after installing. Even exchanged it with another good battery and same issue. "Honestly", think it's the alternator, all signs point to a bad regulator. Guy at alternator repair shop,claim he fully checked it,inside and out,bench and load test, and all checked out, but what i think he's not seeing is that, it's when it's not under load that the voltage drops.
in park, bring the rpms up to the point where its showing good voltage and hold the RPMs there, and turn on every accy you can - voltage should sag but not by much. ... the thing I dont get is you showing 9v ... even with the alt. not excited you should show batt. voltage minus a bit - id say not under 12v or thereabouts
"Update", Had new regulator installed in alternator and still the same issue. so moveing on to the next possible item, thinking "wires" but not sure ? Any suggestions ?
Take the whole car to the alternator repair shop. He should be able to check it out in a few minutes for you.
Yea, tried that. 2 different shops, neither could find a reasonable problem. Voltage at the battery each time, "in park" reads good. Lights on, electric fans, stereo, still all good. Put in drive and voltage drops ! Really doubt it, but could it be the trans or engine and some ground strap, that i am un knowing of ? Any other suggestions or test i can do?
Has this been an issue for as long as you've had this alt? I'm thinking you may have the wrong pully on the front causing it to not spin fast enough at low RPM.
No, just started a few weeks ago. Alternator been on car over 2 years now, working very well. After work going to completely disconnect all extra lines from voltage use,(fans, stereo,unplug headlights, etc) and check it. Ran car Saturday after getting alternator back and on first start all was normal, all gauges were good, volts reading like 14-14.5, as soon as i shift in drive, volts drop to 10 ! In drive,"but at no speed" 9.5-10 volts , neutral or in park 14-14.5 volts. disconnect battery while the car is running and it continues running as normal..
Didn't catch that you had cooling fans.What amperage is the alt? Those fans draw a lot,could be your alt cant keep up if it's 55amp or under.
Nope, had the alternator boosted to like 110 when i first got it, for extra coverage with the fans and stereo. Have already ones, disconnected all and still the same issue. Fans not set to come on till 190-195, issue occurs before temp even gets to that point.. Question: what is the general use of the dual plug wires on the alternator. I mean is that the vehicle volts supplier or the single post on back of alternator ? Car does it with plug in or out, doen't matter, still does it
One prong is to exite the regulator via the warning light/ignition switch the other is voltage sense. Upgraded SI units dont charge well at low RPM.Especially if they use rewound stator & rotor instead of new. The airgap between the two is crucial to turn on speed & output.
Still an issue, beginning to wonder if a Transmission (200 4r) ground issue ? Voltage only drops in drive, "Park and neutral all good". One wire lockup switch, for power. Any thoughts or suggestions ?
It only does it in drive cause the idle speed decreases. Lower your idle to what it is in gear and see what happens
so your saying it's more of a timeing issue, "Timeing is to low" ? "So when in drive, but not moveing the rpm of the car is dropping to low, which will cause the voltage to also drop" ?
Nope. I'm saying that when you put anything in gear the idle drops because of the trans load and the rpms are to low for the alternator to work correct. That's what everyone is trying to say
Ok, but how do i fix that ? (Not trying to be difficuilt just confused on the direction i should go to fix the problem)
