Fewer and fewer batteries allow the technician to view electrolyte levels or test individual cells. Thanks for contributing an answer to Motor Vehicle Maintenance & Repair Stack Exchange! A single lead-acid cell starts to charge at anything over 2.25 volts. Mike's coach has a battery isolator with a Duvac alternator that depends upon a sense wire from the battery bank for it to determine the charge voltage at the battery. Although load-testing an alternator provides a quick way to test for drive belt slippage, keep in mind that an alternator can easily be overheated when testing for maximum output during low-speed operation for an extended period. With the headlamps on and the HVAC blower turned to âHiâ position, ⦠Consequently, if the alternator doesn’t maintain rated charging voltage at lower engine speeds, the battery will discharge under heavy accessory loads. This is why in some service information for modern vehicles, an OBDII breakout box and a scan tool are necessary to solve some intermittent parasitic power drains. Can a censured congressperson be assigned to different committees if they have been removed from current committee assignments? I'm just trying to figure out the normal operating range of an alternator. However, there is no source for these values. It does sound like a failing battery can cause voltage to run above 15 (and fry alternators - but that's another story). in theorems. During this period, the serial data buses could be communicating and performing some digital housekeeping. This is why the ambient and underhood temperatures are critical data for the charging system. Touch the heavy (BATTERY or BAT) lead at the rear of the alternator with the positive probe. The ECM set a charging voltage of 12.5-14.5-volts. Ideal Voltage Output Ideally, the GM alternator should be putting out anywhere between 13.5 and 14.5 volts. How Ignition Coils And Plugs Find The Path Of Least Resistance, Ford Adaptive Cruise Control Alignment Process, Chrysler's Totally Integrated Power Module Simplifies Circuits, Know Your Engine When Determining Spark Plug Service Intervals. Codes for the alternator can be found in the engine control module and the modules that control the distribution of power to the vehicle. Alternator Voltage Tests. 6.2-9.1 volts, low voltage mark and below. How can I get my H.O. The other critical tool to effectively diagnose an alternator is a scan tool. Unlike changing the windshield wiper blades or changing a headlamp light bulb, this is one check-up that drivers are reluctant to do.They rather go visit a garage ⦠Should a select all toggle button get activated when all toggles get manually selected? This is why a scan tool is essential to diagnosing a charging system. The only way you would see sustained voltage above 15 is with a bad regulator. This might also cause you to overlook critical problems. This test can be completed using a basic multimeter (~$25). This prevents the belt from slipping and reduces vibration. Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. 1. "You should be just fine." The normal range for most alternators to run is ~14.1vdc. If you don’t see the recommended voltage when you check charging voltage at the battery with the engine idling, check the wiring connections at the alternator — not just visually or by wiggling the wires or connectors, but checking for excessive resistance by doing a voltage drop test. Post Reply. Your line of thinking is correct in that a good alternator should be charging in the 14.1-14.5vdc as long as there's no major load on it. Aug 3, 2011 at 3:35 PM #1 #1. Note: I intend to use the electrical system to power a 15V rated device. In most cases of undercharging, the alternator may have an incorrect diameter pulley installed, the drive belt may be slipping or the alternator itself might be under capacity for the vehicle application. A reduced output may be a sign that the alternator is failing, but the drive belt and wiring should be inspected before replacing the alternator. What Justification can I give as for why my vampires sleep specifically in coffins? The battery light on modern vehicles, however, is controlled by data and trouble codes. What is the diference betwen 電気製品 and 電化製品? But on some vehicles, it might be normal to have ev. However, if the alternator produces less than 11 volts, it will cause important systems, such as ABS, wipers, or climate control, to turn off. The last number is 13.5V, which is âVTâ or the voltage that the alternator was held at during the test. If the voltage is not within this range, a voltage regulator may be the problem. When your car is running the cars alternator is charging the battery, this is why you should see a higher voltage. 9.2V seems too low and 16.8V seems very high to be considered normal. The last one I checked was holding steady at 14.4. How do I ask people out in an online group? Because new batteries typically test as much as 25 percent higher than their rated capacities, a recently replaced battery with a bad cell can occasionally pass both a conductance and a load test. The alternator should be replaced if AC voltage of more than 50mV is detected (in some cars as much as 100mV is acceptable). Best of all, in this scenario, the system needs less tension and a narrower belt can be used. Making statements based on opinion; back them up with references or personal experience. After watching this video, you will be able to safety test alternator voltage output. Bear in mind that the actual voltage can go down as well as up so design for a range of about 17-32 if the electronics are critical. My second hand alternator had been going bad for a while struggling with voltage and eventually lighting up the dash warning lights. Car alternators have voltage regulators that usually prevent over-voltage charging and usually run around a 13.8 volt mark. The actual charging voltage designed into a voltage regulator is dependent upon factors such as how far the alternator is located from the battery and the ambient air temperature surrounding the battery as calculated by the PCM. A good charging system has the following characteristics: A fall in battery voltage should be accompanied by an increase in charging current and vice versa. P0A1A-87 - Generator Control Module - Missing message Pulled codes and these are the following. Since an alternatorâs output can vary both up and down from 13.5V in real-world situations, itâs actual output limits will vary from the idle and rated numbers. These new pulleys allow the alternator to “free-wheel” or “overrun” when the belt suddenly slows down. When voltage drops below 13.5 volts, the regulator will apply current to the field and the alternator will start charging. If the voltage dips below the optimal range, then the regulator kicks in to get the alternator to make more voltage. Battery voltage is like 12.6V with the car off.. Battery at 13.7 volts disconnected, 14.7 with engine idle or revving, while various small intermittent problems suggest voltage is low? It should be 13.5 volts to 14.2 volts. Alternator voltage must be above 10.0-volts and the communication must begin within 3-seconds or the ECM will set a trouble code. ll not be able to keep up with the load when idling, and the lack of cooling compounds the problem even further. This means that load on the engine is controlled to reduce parasitic loss at the crankshaft. For some, a constant 13.6 volts is an indication of a problem. However, these pulleys have a limited lifespan due to how they operate internally. A healthy alternator is typically in the low to mid 14s as Paulster2 stated. Who can use "LEGO Official Store" for an online LEGO store? When the system is run higher than that (in the range you are talking about ... 15vdc plus), it will boil (and ultimately ruin) the battery. The symptoms of a sulfated battery are that it charges very quickly and produces a very low amperage discharge rate. That 15 volts is too high for direct battery charging. Some systems might even stop charging if an extreme load is detected and set a code. Maybe such a standard does not exist? Depending on the load, the regulator may put out more than 15vdc, but this will be on a very short term basis. Shut the engine off and leave the meter set for the 12V range. In hindsight running the bad alternator for three weeks was a bad idea, one morning I smelt a burning smell. rev 2021.2.9.38523, Sorry, we no longer support Internet Explorer, The best answers are voted up and rise to the top, Motor Vehicle Maintenance & Repair Stack Exchange works best with JavaScript enabled, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company, Learn more about hiring developers or posting ads with us. Still, itâs perfectly normal for others to see the alternator not charge at all intermittently. When the system is run higher than that (in the range you are talking about ... 15vdc plus), it will boil (and ultimately ruin) the battery. I charged the battery once a week while I waited for the regulator to come. If this happens, charge the battery out of the car to confirm it is still good. Many so-called alternator problems turn out to be nothing more than a bad connection at the alternator or a bad wiring harness. If this is the case, it only means that the alternator is not charging, but does not reveal why. To charge the battery, the alternator voltage output has to exceed a minimum charging voltage. For others, itâs normal to see as high as 16 volts for long stretches. This minimum charging voltage is 13.8 volts dc across the battery terminals, or at the output of the alternator. You can be confident that a healthy system will be above 11v, and if you're concerned about over-voltage conditions from unhealthy vehicles, then put a regulator in your input circuit. How to check the alternator voltage output is one more simple check-up you can do on your own. Can I say that I am utilizing same terms & conditions and privacy policy of this (xyz) website? I appreciate what you are saying but ideally I'd like a specification that I could reference, e.g. This wide discrepancy in voltages is due to the fact most alternators are controlled by the ECM or PCM to improve fuel economy. Many late-model vehicles use a decoupler pulley on the alternator. Due to the problem, I have been monitoring the battery voltage. I would think 13.5-14.5 would be a more normal/healthy range.. no? Take time to look at the service information. As a rule, the key-off current drain on most late-model vehicles should be less than 50 milliamps (mA). Many Asian vehicles, for example, have higher charging voltages of around 15 volts. This should be approximately the same as the battery's voltage reading. The rule of thumb that states 12.6 volts equals a fully charged battery and 12.2 volts means it is 25 percent charged, is starting to change with some modern batteries and charging systems. about his research, and about courses that deal with his specialty/my career goal? For some alternators, it’s normal to see as low as 13 volts. I checked the voltage and both the battery and alternator seem to be working in spec. A dead or weak battery can throw off a ripple test, however, so you must make sure the battery is fully charged. The voltage, when the engine is running, should be in the range of 13.5-14.7 volts. ... #4 ⢠May 5, 2011. One test is not enough if you are diagnosing a charging system problem. Why won't the top three strings change pitch, How to avoid an hyperref bug (?) The alternator was replaced about 1.5 years ago with an OEM unit. Bear with me on this....cold engine, 32 degrees out, start engine and alternator pegs out at 15 volts or so. All too often, the alternator is condemned as the source of the problem if only battery voltage is present with the engine running. So the PCM will only produce enough voltage to ⦠If as Paulster2 says >15V is bad then we can limit the maximum voltage it to 15V and state that the alternator must be healthy. Although the car will run with no noticeable issues when the alternator output is between 11 and 13 volts, it will not charge a battery to full capacity. On older vehicles, the battery light would turn on the alternator light when the alternator output or battery voltage dropped below a preset value. ... low battery voltage, alternator try to charge low batt, or voltage regulator issue (inside alt). If youâre readings are significantly higher or lower than these then it would indicate a ⦠If there is, the voltage will be down some from this. A voltage regulator helps regulate the voltage that an alternator provides. The LIN interface provides a simplified method of reliably achieving the bidirectional communication required for maximum alternator performance in an intelligent charging system. How did old television screens with a light grey phosphor create the darker contrast parts of the display? A shorted diode in the alternator can still allow a charging voltage of up to 13.3 volts, and can be detected by the battery going dead within several hours. In what medium do Gravitational waves propagate? Electronic: VIDEO: How Modules Manage Alternator Power, Electronic: VIDEO: Checking Key Fob Signal And Operation, Diagnostics: VIDEO: No-Start No-Crank On Vehicles With Transponder Keys, Video: VIDEO: Blower Motor Electrical Circuit, Video: VIDEO: Engine Knock Sensor Problems, News: Beta Tools USA Establishes North American Presence, Products: Knipex Introduces Mini Bolt Cutter, Products: Save Thousands With K-Seal Ultimate, The Importance of Worn Center Bearing Replacement. How to diagnose if battery is faulty or alternator is faulty. If not, the replacement alternator can fail sooner than expected. The alternator should be tested with the engine idling and electrical accessories, such as the radio and headlights, turned off. Depending on the battery type, the maximum charging voltage should start high and ⦠Also, most modules on a vehicle will set a code if low system voltage is detected. site design / logo © 2021 Stack Exchange Inc; user contributions licensed under cc by-sa. Tester August 9, 2017, 1:33am #2 Your Crown Vic charging system voltage is regulated by the Powertrain Control Module. @Lathejockey81 The device is specified to work from about 9V to 15V, however I could re-rate it to work higher at a lower current. Not knowing what controls what, and how it is supposed to function, can cause a misdiagnosis. Alternator ⦠How can a battery indicator be on when the alternator is providing adequate voltage? ne test is not enough if you are diagnosing a charging system problem. Interest: what is the most strategic time to make a purchase: just before or just after the statement comes out? The battery provides the initial voltage and amperage to crank over the engine, afterwards the alternator takes over in generating the power needed to run the electrical systems in the vehicle. Using a quality engine ground for the negative probe, again read available voltage at the alternator. If the replacement alternator does not come with a new pulley, be sure to install the correct pulley with it. Alternator Testing: What Is The Correct Voltage? At idle under minimal load, a Toyota or Lexusâs voltage at the battery should hover at ⦠The voltage varies from 12.3 volts to plus 15 volts. If there is a dead or weak cell, normal charging voltage can’t be achieved on a battery with a bad cell. At the other extreme, a battery that is sulfated due to being undercharged or not seeing constant use will maintain normal charging voltages.
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