Alternator low voltage at idle. This seems to be a little on the low side.
Alternator low voltage at idle. Fit just fine. Mar 30, 2018 · Engine at operating temp with lights, fans on, radio, etc on I am getting 11 volts at idle My setup: J2 Fabrication 240 amp alternator Big 3 "0" gauge wiring upgrade Raptor e-fans (63 amps) Two aux fans on my condenser (9. 6 at 1800rpm. 5 and 12. Oct 1, 2015 · The originally installed alternator on the Ford 6. 4v. pulley would help with low rpm voltage/amperage at a risk of too much alternator rpm when doing WOT blasts(if the pulley diameter reduction was too much), but only having 13. 3-12. Oct 29, 2013 · I just got a mx5 (Miata) NA (1990) and I noticed that the voltage at idle is quite low, 12 – 12,5. With the lights/heater off voltage is about 13-13. The car is a Mitsubishi Lancer 1. Dec 30, 2021 · Start the engine, turn headlights on and observe the voltage on the meter. I think either alternator, or voltage regulator. It's usually fine when I first start it, but gets worse after the truck gets warm. 5 volts. There are problems if it drops below this range. 6 when you increase rpm to 1500, then alternator is doing it's job but just barely because at idle it can't handle the load. What I have done:-New 60 amp alternator Aug 5, 2011 · alternator not charging my battery new battery, new alternator (2 actually), checked wiring,checked fuses, checked volts only 12v going through the whole system. 8. I personally rebuilt the unit with a brand new diode set, brushes, voltage regulator, and the "Iceberg alternator" housing (with extra fins for heat dissipation). A small difference, like 12. The bulletin covered 1990 through ’97 passenger cars and trucks. Usually the brushes are worn down. I have no mechanical experience, but looking up on the internet I found that a voltage around 14 V should be expected. ) Aug 23, 2019 · This low idle issue started when I replaced front cat converter (one with the manifold) last year. And voltage is fine with a/c and rpms anywhere above idle. 2 volts) to effectively charge a 12 volt car battery. Do ya'll think the alternator is starting to call it quits under higher load? Jul 14, 2009 · Alternators rarely have full voltage at idle. 25" alternator pulley 750 idle rpm 6. 3 (just got my first one this year in April). 4 at idle whether or not accessories are on. You could have a "chicken and egg" thing going, the alt is fading out at low speeds which causes the low-idle surge. How Do I Fix Low Voltage At Idle? To fix low voltage at idle, check alternator belt tension, battery terminals, and alternator output. Now I purchased a used but guaranteed working order through EBay. Feb 8, 2013 · Oluseun, with the engine running the gauge should measure the output of your alternator. (Which seems low to me. Today I took out the alternator and checked the bushings etc, everything looks ok, except for the small bearing, it’s not 100%. The best way to make an alternator charge at low RPM is by installing a smaller pulley on the alternator to enable it to spin faster and increase the charging efficiency at low RPM. The Allison loves 12v all the time. Nov 13, 2017 · The load shed operation is a means of reducing electrical loads during a low voltage or low battery state‐of‐charge condition. 5L, with a petrol engine, and I think it has a 85 A alternator. 5 and 14. Most economy vehicle ECU minimize fuel consumption and thus alternator output at idle providing just what's needed to keep the vehicle running while stopped with minimal charging if any. 3V for me, and will reduce as it gets closer to being charged. Jun 29, 2016 · Sounds like a weak alternator, using a smaller alt. On older vehicles, the battery light would turn on the alternator light when the alternator output or battery voltage dropped below a preset value. Most voltage gauges are not calibrated, they simply indicate a correct range of voltage for your battery while the engine is running. The voltage should not dip below 12. The cables look "pristine" I had already cleaned with baking soda. Voltage drops on the positive side of the charging circuit can cause undercharging. If the voltage does not change when the engine is started, if it does not get above 13 volts, or if it charges above 15 volts then the alternator may be faulty. 4-14 volts while running. Nov 14, 2023 · “Low voltage at idle” indicates that there is insufficient electricity production during these sluggish periods from the alternator. following are the behavior of the idle rpm, voltage fluctuation during this test. Numbers haven't changed. Some a little more, some a little less. Nov 21, 2017 · The other critical tool to effectively diagnose an alternator is a scan tool. The alternator is a little more tricky. If you have one of those that shows the voltage without the engine running, then check your gauge for a bad resistor on the dash panel. 8 volts, may indicate a wiring issue between the alternator and battery. Previous topic - Next topic. May 26, 2021 · Although alternator manufacturers, rebuilders, and suppliers typically refer to the rated output in promotional materials, both the ISO and the SAE require a format of “IL / IRA VTV,” where IL is the low, or idle, amperage output, IR is the rated amperage output, and VT is the test voltage. Check the voltage at the output of the alternator when the engine is idling, it should around 14 V in most cars, maybe a bit lower (13. Symptoms of Alternator Voltage Fluctuations at Idle. The voltage fluctuates from 12. It seemed to do a little better than my original but still low. If alternator voltage fluctuates at idle, don't worry. 5 volts at idle in neutral. Jun 11, 2010 · Fully warm @ idle my voltage will drop down to 11. Jul 26, 2010 · Used the OBC voltage redout to watch my voltage and found that while driving, above about 800 rpm or so, voltage fluxuated between 13. We realized mastery doesn't require elite degrees or industry secrets—just knowledge presented coherently. Jan 29, 2014 · Hello everyone, I am wondering what the lowest voltage an alternator should produce under full load at idle is. I figured if it was the alternator my battery would eventually die, but the truck starts no problem for a couple months now. 8v, alternator output is 13. Alternator is new and battery is a new optima red top. Aug 17, 2007 · C5 Tech - Low voltage output from alternator - Installed a new race proven alternator and not getting the proper voltage. I'll do that next. We have shared the root causes, implications and fixing ways of alternator fluctuating voltage issue. 8 and 14. 6 amps) Taurus smog pump (15 amps) Two Walbro 465 pumps (28 amps) 2. The symptoms of alternator voltage fluctuations at idle are usually quite noticeable. 5v of each other. 5 at idle and 11. If the voltage is low, the alternator may be on its last legs. Install a Smaller Pulley. Sep 21, 2024 · I largely cured dim headlights and low voltage at idle with the AC on (with stock alternator) with adding an idle solenoid on the carb and retuning my distributor to run 17/18 degrees initial advance + manifold vacuum on the vacuum advance. 5-14. Mar 15, 2005 · Get one and look at the alternator's output voltage when the engine is idling warm with no added loads (defroster, vent fan, headlights, etc. Once everything warms up, at idle I see my voltage drop below battery voltage. given that the alternator is in good condition and not reaching the end of its life span, the alternator should charge 14 volts when idle. When I turn on HVAC blower to high and a Spal trans cooler fan it drops around 13. 7 volts @ 1200 engine rpm points toward the alternator itself (or a wiring issue)as being the problem. Measure the voltage across the battery and the big bat alternator terminal to alternator case. All things being equal i. I've seen it drop as low as 10V, and unplugging the terminal from the field winding gives me batter voltage as expected, the alternator is becoming an inductive load at idle when hot. Many vehicles have a voltage gauge – indicated usually by a graphic of a battery. The idle boost operation is a means of improving generator performance during a low voltage or lowbattery state-of-charge condition. First two alternators were giving low voltage as per Autozone battery and alternator check. com If the reading stays at 12. 5 is good. Now I’m 14. A good alternator should put out between **13. 7 at 2000-2500 rpm. You are most likely to see problems in the alternator when it's cold and idling, but unfortunately that applies to the wiring as well. Connector to alternator, alternator itself, fuse links between alternator and battery, or the connection is not attached. 6 VDC, which I think is way too low (that's basically the battery voltage). Oct 17, 2022 · What Should my Alternator be Charging at Idle? What an alternator will charge at idle varies and can be influenced by factors such as; condition, age, etc. Usually if the battery is not target (80%) it will be full charging, even when idling--that is something like 13. ) The voltage should be something like 14. All of these can affect the alternator’s ability to properly charge the battery and can cause it to fluctuate in voltage at idle. The fact that you see voltage dropping BELOW the battery voltage makes me think that it's not the alternator. 6 volts or lower, your alternator is not charging the battery, and there is likely a problem with the charging system. Low voltage also comes from poor electrical connections, a loose drive belt, low engine idle speed, or poor ground. 9-14. I have not checked wire from battery to alternator . You can probe it at the battery terminals. You need to force current into the battery with a voltage that is greater than that of the battery. Voltage was 13. The alternator’s pulley is connected to the engine via a belt. 5 to 14. I had the car towed home and did start it to move it in the driveway. 5 ish) if the battery is fully charged or if the alternator pulley doesn't allow full output at idle. There are two things that you are looking for. Jun 11, 2023 · Low idle voltage can be caused by a failing alternator, loose belts, or corroded battery terminals. It should produce between 13. 0, which still sounds low, but I'm still fairly new to the 7. Hard to say. The stalling is most likely a symptom of low battery voltage from poor alternator charging. Idle speed is 800 rpm in park/neutral, 600 rpm in gear. Mar 28, 2017 · Check for voltage drops at the positive and negative battery cable connections, the alternator BAT+ power connection and the engine ground strap(s). 6) or it won't charge. Wait 10 minutes and check the battery voltage. 0L with a single alternator appears to have a low voltage reading in the 11-12 range after startup. The more spark plugs that are affected due to the poor performance of the alternator, the more severe the rough idling issue will be. Jun 8, 2021 · If the voltage gauge shows 9-10 volts the alternator is your primary suspect. Our Story. However, when you measure amperage from the unit, it is generally in the 80-90 range at idle. Yet because the alternator is the heart of the charging system, many people jump to the mistaken conclusion that the alternator must be bad if any of these conditions exist – and end up replacing the alternator unnecessarily. Jun 28, 2016 · Most modern vehicles control the alternators field coil and idle RPM to optimize the alternator's output. The "L" terminal is used to excite the rotor windings when the alternator is not turning but after the alternator starts turning the alternator will provide its own excitation and it also adjusts the amount of excitation to keep the alternator at the proper voltage. Turn headlights on to put a load. 4 to 12. Jul 16, 2011 · I have been intermittently getting low voltage (less than 12 volts) with the A/C on while idling. This seems to be a little on the low side. Sep 26, 2023 · General Motors issued a Technical Service Bulletin (#43-64-07A) dated January 1997, to address low voltage readings or dim lights at idle. " Now when the engine is running, I get about 13 V of voltage: last time I checked, the tension was constant at 13,07 V (with no electric loads on), both at idle and at higher rpms. These symptoms can indicate a failing alternator, and addressing the issue promptly can prevent more serious damage to your vehicle’s electrical system. With the car off, turn your headlights on for 1/2 minute. 5 when it should be 14+ volts. Dec 30, 2018 · The red battery light goes off for three reasons, but it means there is an electrical problem. Feb 25, 2023 · When the alternator produces 13 volts or fewer volts instead of 14 volts which it’s supposed to produce, your engine begins to misfire. I had some one start the car and slowly bring up to 2000 rpm. Another cause could be a bad alternator diode, which can interfere with the signals being sent to the ECU. May 9, 2018 · The reading was 12. 60" balancer pulley Mar 28, 2021 · It could be the brushes, bad voltage regulator or a leaky diode pack. The battery light on modern vehicles, however, is controlled by data and trouble codes. Also stereo starts crapping out. Dec 20, 2022 · A bad alternator can cause a rough idle by not producing enough voltage. Alternator and Rough Idle Jul 10, 2024 · Here’s what to do to make your alternator charge at low RPM: 1. I know the battery temperature sensor controls voltage output, but this is Alaska, and in spite of climate change, it still exhibits these symptoms at 35 degrees on a cold start. System Voltage to Low, System Voltage to High or a fault was detected in the alternator field control (the PCM control of the alternator). 0 Members and 1 Guest are viewing this topic. I checked the voltage at the battery coming off idle today. 5 volts, which is ideal. Normally, the needle pointing straight up means the alternator is charging the battery correctly. I replaced the alternator with a NEW Mopar unit. Aug 8, 2016 · Charging problems can have many different causes, with the alternator being only one of many possibilities. 2-13. Jul 14, 2019 · If you don't have resistance on the "L" terminal then I recommend that you add some. With the AC off, it is measuring 12. 5. If the alternator is working properly the voltage will be higher than normal battery voltage (12. The dropping of voltage below 9. With the car idling @ 1000 RPMs and every electrical device turned on: high beams; front fog lights; rear fog light; brake lights; reverse Weird electrical problems – Low voltage from a weak alternator can cause erratic or malfunctioning electronic systems, such as the radio, power windows, or dashboard gauges. Sep 22, 2019 · My alternator (CS130) stops charging at low RPMs, particularly when the engine is warmed up and on a hot day. This is the third alternator I have replaced in last 8 months. Oct 6, 2023 · I also think it's odd that it would be battery voltage at a stop and then full charging when moving. . But your car is so modified that you may be fighting different issues. 6; if it does, it indicates the battery is being discharged and the alternator needs replacing. A low voltage output can lead to issues with fuel delivery or spark plugs not firing correctly, which can cause stuttering and idle issues. Voltage is 10. 3 to 15. Sitting at a light, at idle, in drive, with headlights and radio on, (no ac) voltage would fluxuate around 12. Poor ground connections are an often-overlooked cause of low charging output and alternator failure. Before starting the test I have noticed that on the screen the DME commanding live volatge for 15. Jun 17, 2020 · The continuing voltage drop while running speaks to no alternator output. When fully warm at idle with new used alternator my voltage will Jul 20, 2017 · At idle Torque pro shows voltage bouncing between 13. 4V. 4 or 13. So why the low voltage? Alternators are about wattage, which is the product of voltage and amperage. 4ish at idle. Idle is about 650rpm. The charging voltage should be between 13. Tested it at O’Reilly, tester says voltage regulator is bad. e. 2 volts is problematic to the FICM, it usually stresses them to the point of circuit destruction. The low voltage may be indicative of issues with your alternator. At idle a Blue Sea voltage meter shows 13. Started by TripleJ, October 03, 2014, 02:35 PM. This is a function of temperature too but the Go to the drop-down menu bar at the lower left corner of the Waveform Library window and select Alternator voltage or Alternator current. Now my trans was acting funny when my alternator was taking a shit. Keep in mind you are seeing the battery voltage and not the alternator output voltage so it is normal to see some lag. 5 at idle in gear and 14-14. Battery shows 12. Oct 6, 2012 · At idle with the AC on, my alternator output voltage is only measuring between 12. Start the car, check you idle voltage, and also when revved up to 2000 RPM or so. As soon as I turn off a/c, car voltage jumps back to around 13. 4 at idle. I would think it should always be able to produce at least battery voltage (12. So running the glow plugs + recharging from start up + accy loads = more than alternator can keep up with for a few min. Jan 15, 2024 · The common issue is low voltage at idle where the voltmeter reads 11. Also the voltage at the battery and the voltage at the alternator should be within 0. 5 or so at 2k. Aug 7, 2015 · Defective alternator diodes can be detected by using alternator test equipment that measures the amount of alternating voltage (commonly known as “ripple”) in the charging circuit. 1 and 13. If the voltage gauge shows 18-19 volts, the primary suspect is loose, dirty, corroded or damaged battery/alternator connections or cables. Jun 2, 2004 · I would run the engine at idle and measure the voltage at the battery. Jun 10, 2016 · I had a single 105amp and I put the 145amp on it. 2-14. Aroung 12. I grounded the dark green as i have read to do and the alternator never turned on. Some accessories will power off if voltage is too low. Alternator amp output test. 0 and occasionally 13. Voltage is right where it needs to be. Nov 24, 2011 · Alternator output Thanks for the suggestions. It should be 14. A car alternator needs to be putting out at least 13-14 volts (ideally between 13. What could be ? I still have factory alternator and voltage regulator single pulley . Jan 20, 2011 · The manual says the glow plugs can stay on for up to 2 min after start up. 8-13. At idle with an adequately charged battery and no load the alternator shows low voltage and misdiagnosed frequently that the alternator is not functioning properly. I was getting the same voltage fluctuates from 12. Idle boost consists of three steps: idle boost 1, idle boost 2, and idle boost 3 Dec 27, 2017 · INPA ALTERNATOR VOLTAGE TEST AND SYSTEM BEHAVIOUR: using INPA Activate - generator , I was able take control of the alternator output voltage from DME. 6v- 12. Feb 10, 2015 · I was testing my car's alternator with a multimeter and I wonder if the voltage under full load is normal. 9v to 14. If voltage goes above 12. Oct 3, 2014 · Low voltage at idle, alternator at 14+ volts. If the voltage is higher by more than 4 volts, the regulator may need repairs or replacing. Nov 12, 2018 · the car starts on its own and the battery is holding voltage. I have power coming through the white cable going to the back of the alternator and not the green. Our journey designing innovative devices had immersed us in convoluted electronics. Last, but not least, measure the voltage drop between the alternator and battery by connecting a digital voltmeter in parallel between the alternator (B+ Apr 7, 2016 · The voltage gauge fluctuates between 12 and 14 or so. Apr 8, 2012 · On a cold start, and at or above 1500 RPM it appears to work fine. So I instinctively thought alternator. While a higher output alternator is often the cure, it’s best to first check the charging system circuit to ensure that the connection between the alternator and the battery is not creating unwanted resistance. If you put a good digital or analog meter on the battery posts you can see how much the voltage swings while the idle speed is surging. 4. Thats a huge current drain. 9v roughly. 9v almost killing my car and go up to 12. 6 volts or so) even under a full load (all the stock electrical accessories on) with the engine idling to Aug 9, 2021 · "What is normal alternator output voltage? The voltage should read a minimum of 13 volts. I bought a new alternator from Oreillies and installed. Nov 25, 2020 · When the condition is present, unplugging the alternator wiring harness makes the noise stop instantly and returns as soon as I reconnect. Further guidance When the engine is running, an alternator generates electrical energy to supply the vehicle’s on-board electrical systems and replace the battery charge consumed during cranking. Oct 7, 2016 · Under these conditions, voltage is between 11-12 volts. Jun 26, 2017 · My 71 road runner at idle with loads on voltage low blinkers run slow wipers slow and headlights dim but when revving or accelerating voltage goes up and everything runs much faster. See full list on cartreatments. Other possibilities include a failing voltage regulator, or perhaps an alternator pulley that is too small. I got a new ac delco not a reman. Also should mention the battery is in the trunk. 1v . 5 or 12 volts instead of closer to 13. Mar 11, 2016 · I've tested with a hand-held voltage gauge at the alternator and confirmed that the alternator simply isn't kicking out voltage at idle. If the alternator is putting out too much voltage (15+ volts), it is likely your battery acid will boil over out of the battery. A good alternator should put out between 13. lgr rfxgdn bbkotbkk cfos tgydlic dqpa abgeo njoh irk nrj