Ok. My car alternator and battery tested good yet it has to be jumped off and after driving 1/4 of a mile it cuts off and dies
What else will make my car drain the battery. Or is there some kind of delay from the alternator that isn't charging my battery? But even jumped off all the lights are dim and it doesn't run long. Then after cutting itself off it acts like the battery is dead. Keeep in mind I already had both tested. and there good.
My car has an automatic transmission.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
You need to have the battery and charging system checked again. You have a bad connection to battery or battery is bad and not charging. I recommend cleaning battery terminals by removing and cleaning then and reinstall then test entire system again.
How to Identify and Fix Common car Problems ?
Our sources include academic articles, blog posts, and personal essays from experienced mechanics :
Keep in mind, just because the Alternator tests fine, does not mean the system is fine. The charging system is composed of wiring that not only supplies the battery and system with DC power, it also “senses” the voltage that`s out in the system in order to properly set the voltage leaving the alternator.
Charging problems can be caused by electrical faults in the alternator or voltage regulator, poor wiring connections at the battery or alternator, or a slipping or broken drive belt. Since most late-model import alternators are internally regulated, a failure of the regulator means the alternator must also be replaced.
If your alternator is failing, its voltage may drop below capacity, causing the battery warning light to appear on your dash. Similarly, the battery light will also appear if the alternator is exceeding its voltage limit, depending on how much stress it is under.
A simple test to check the working of the alternator is by running your car; and then unplugging the positive connection of the battery. If the car stops, then you most likely have a problem with the alternator.
Symptoms of a burnt out diode:
The engine will begin to run rough, lack power and eventually stall and not start again. The battery warning light will turn on, warning you that there is a problem with your alternator charging system. The headlights will become dim due to reduced battery voltage.
Alternator Low Voltage Between 10-20% of rated output
This indicates lack of excitation, which could be: The Automatic Voltage Regulator (AVR) fuse (if fitted) has blown. The Automatic Voltage Regulator (AVR) has failed. A break in the excitation circuit between the AVR and the exciter stator.
One of the most common problems you`re likely to experience with an alternator is a failure in the bearings. There are needle bearings in the alternator that allow the rotor to freely spin inside the housing, and those bearings can break down over time as a result of exposure to heat and dirt.
Basically, the light indicates a battery charging problem. If the light comes on and stays on while driving, this means that your alternator is running solely on energy stored in the battery. If you continue driving, your battery will eventually drain and your vehicle will stop working.
Probably, the most common symptom associated with a bad regulator is flickering, dimming, or pulsing lights. To be more specific, you may notice that the vehicle`s: Headlights fluctuate between bright and dim, without you doing anything. High beam isn`t working as expected.
The alternator is driven off the engine by a belt, which allows the alternator to convert mechanical energy into electrical energy through magnetic induction. Most of the time, there`s a high-amperage fuse or fusible link between the alternator`s battery terminal and the battery.
Leaky or shorted alternator diodes can cause rapid changes in the output voltage of the charging system. In addition, bad diodes can also allow current to leak from the battery back through the alternator to ground.
Yes, you can check your alternator by disconnecting the battery. However, it`s important to note that this isn`t the most accurate way to test the alternator. If you want to get a more accurate reading, you should take your car to a mechanic and have them test the alternator for you.
A good alternator should maintain battery voltage between 13.9 and 14.8 volts (14.2 is optimum). Even worst-case, with all accessories turned on, there should be at least 13 volts at the battery.
The voltage regulator controls the amount of power distributed from the alternator to the battery in order to control the charging process. Regulators are designed with different functions and work depending on their specification.
Parasitic drain
A parasitic drain refers to when your car`s battery continues to drain even after the car`s parked, and the amount of drainage is much higher than normal. Usually, it`s a faulty accessory in the car causing the drain – for example, a sensor or interior light doesn`t switch off automatically.
The ignition relay is essentially an electrical device that works as a switch for the power to the ignition system. Its job is to make sure electricity flows from the battery to the different components that need power. A bad relay will drain your battery and make it difficult to start the ignition.
Your car`s alternator may fail for various reasons: Age and use-related wear is often the reason behind a dying alternator. Engine oil or power steering fluid leaking onto the car alternator can lead to its failure. Prolonged idling while using multiple electrical accessories can prematurely wear the alternator.
If your alternator voltage regulator is working correctly, your battery`s voltage output should cap around 14.5V. If the reading is above 14.5V, you likely have a faulty voltage regulator. If the reading is below 13.8V, your battery is weak and will probably need a replacement.
There are many reasons your car`s battery might be dead, and one of them happens to be a broken voltage regulator. This is because when this part burns out, the battery will no longer charge, meaning it will eventually die.
With your car still in park, slowly press on the gas until your car reaches 1,500-2,000 RPMs. Read the output on the multimeter. The regulator should cap the output of your battery at around 14.5. If the voltage reads over 14.5, it probably means that you have a faulty regulator.
In fact, when the temperature is below 32 degrees, car batteries lose 35% of their strength, and at zero degrees they lose 60%. If you`re not prepared, you may find yourself stranded on the side of the road with a dead battery and an expensive tow in your future.
If the car cranks when you turn the key, but the engine won`t start, it could be because fuel isn`t getting to the engine. One potential reason for this could be dirty fuel injectors. Over time, the fuel injector nozzles can become clogged with rust, corrosion or debris.
#1 – Dead Battery
A battery that is drained or can`t hold a proper charge is one of the most widespread problems across all automobiles.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
Ok. My car alternator and battery tested good yet it has to be jumped off and after driving 1/4 of a mile it cuts off and dies
ANSWER : You need to have the battery and charging system checked again. You have a bad connection to battery or battery is bad and not charging. I recommend cleaning battery terminals by removing and cleaning then and reinstall then test entire system again.
Car died while driving so I replaced the alternator and battery and car won’t attempt to turn over. What else could it be?
ANSWER : The initial failure was likely caused by a sudden fuel system (e.g., failed fuel pump) or electrical (including ignition) faiure. Prior to performing diagnostics be sure you have a fully charged battery that passes a load test. Then, confirm that the engine immobilizer system (security system) is not activated thus preventing the car from starting. If the starter motor is not functioning, check for power to the starter motor when the key is held in the "start" position. If there a large voltage drop at the starter motor or no power at all, you may have a faulty ignition switch but you do have to check out the entire starter circuit, which includes grounds, wiring (some of which is very heavy cabling), fuses, relays, the ignition switch and terminations. On the other hand, if the starter motor is getting power but the starter doesn’t work, then the starter is condemned and replaced. If you desire that a certified mechanic resolve this, please simply request a no start diagnostic and the responding certified mechanic will get the problem diagnosed and repaired for you. Please let us know if you have further concerns or questions as we are always here to help you.
My car will not start Intermittently. I purchased a new battery 2 weeks ago and yesterday the car wouldn’t start. Got a jump and
ANSWER : The issue you are having is probably due to an intermittent fault in the starter motor itself or a deficiency in the starter electrical circuit, for example a large voltage drop due to a poor ground or a high resistance connection. These issues can be readily diagnosed and resolved on a mobile basis if you request a hard starting diagnostic. If you request that diagnostic, the responding certified mechanic will get this resolved for you promptly. Based on Toyota’s Factory Service Manual, the battery should not be disconnected if the vehicle engine is running. The battery acts as a large resistive voltage sink and consequently taking the battery out of the circuit, while the alternator is still running, can create a voltage spike on the car’s electrical system which is not good for voltage sensitive components such as the engine computer. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
Just put a new carburetor, battery, starter relay, alternator, car stalls out while driving and battery dies when restarted
ANSWER : The battery should be load tested. Simply charging the battery or measuring voltage is not adequate. Measure charging output, too. You want to confirm that the ignition system, including for instance the ignition coil and ignition switch, are not intermittently cutting out. Coils can fail as temperature rises (resistance increases with temperature) so if you run the car for a while and all of a sudden it quits, measure the resistance of the coil windings to see if that provides a clue. Apart from that, the ENTIRE primary side ignition circuit has to be checked, using voltage drop testing (and testing of the hall effect sensor in the distributor), to rule the primary side in or out. If you want the required diagnostic steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a stalling diagnostic and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
Replaced alternator on car 2 times each time shows it’s charging 14v let car run for a little bit then test drive and car voltage
ANSWER : There are reports that the replacement alternators will not communicate with the engine computer and will not charge correctly. I recommend using only the manufacturer approved replacement part. It can be new or remanufactured but approved for use in the vehicle. Some lower cost alternators on the aftermarket will have charging problems since they will not communicate with the ECM on the vehicle and will stop charging.
Car battery dying quickly especially after longer driving
ANSWER : It sounds like the alternator is not charging the battery, when are you driving long distances. Running all the accessories and then shutting it off can cause the battery to be too weak to restart the car. If the alternator is intermittently not charging, then you may have other wiring issues or just an intermittent problem within the alternator. Have the charging system checked by a mechanic after driving it and not shutting it off, to see if the battery is being charged. You may also have a body control module issue with extended storage mode. The dealer can check this mode with the special scanner and checking the extended storage fuse is not installed.
Battery dying and both alternator and battery passed for good when inspected
ANSWER : If the battery passes a load test and charging system output has been measured and is within specifications, the only reason a battery will discharge is if the car sits for a long period of time (batteries will self-discharge even if not used) or if there are parasitic (excess) loads on any of the car’s electrical circuits. If there is excess current flow that is slowly draining the battery, a Mechanic would use an ammeter to test all of the various circuits until the faulty circuit is found. Then that circuit is traced to find the fault and repair it. If you want these steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an electrical diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
Battery good, alternator good, brand new alternator cable, still not charging.
ANSWER : Hi There,
The first diagnosis of the bad voltage regulator is likely the cause of your charging system not properly charging the battery. When the voltage regulator is not working properly, this may result in the alternator allowing too much power to be delivered to the battery resulting in damaging wires and prematurely sometimes destroying the battery. In other cases it may result in the alternator not supplying enough power to the battery, resulting in undercharging the battery or not charging it at all. In some cases when a battery is too weak or damaged, it may no longer hold a charge for any length of time, in which case the alternator may be doing its job, but the battery is just simply too weak to hold a charge. In either case, I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.
The first diagnosis of the bad voltage regulator is likely the cause of your charging system not properly charging the battery. When the voltage regulator is not working properly, this may result in the alternator allowing too much power to be delivered to the battery resulting in damaging wires and prematurely sometimes destroying the battery. In other cases it may result in the alternator not supplying enough power to the battery, resulting in undercharging the battery or not charging it at all. In some cases when a battery is too weak or damaged, it may no longer hold a charge for any length of time, in which case the alternator may be doing its job, but the battery is just simply too weak to hold a charge. In either case, I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.
