Alternators keep dying and killing batteries

The faulty alternator in my 2011 Jeep Wrangler wore out the last battery I had. I replaced both and that worked up until recently. The vehicle has about 172,000 miles on it at this point and I obviously need it to be reliable. The battery has been running low on power again so I think I have the same problem. Is there an alternator on the market that will stand up to my use?
Experienced mechanics share their insights in answering this question :
Your alternator may be working fine and you just need to replace the dying battery. Most alternators tend to last a lot longer than most batteries.

The factory alternator on your Jeep is more than capable of handling your needs and there is no alternator claiming to last for extra long mileages. An alternator will last longer if the battery and cables are kept in good shape and the electrical load is not exceedingly high on a regular basis.

I suggest having a certified mechanic, such as one from YourMechanic, check out both the battery to properly diagnose the issue. If required they can also replace the alternator for you.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

If your Jeep keeps dying, it is likely due to a failing alternator. The alternator is what charges the battery and provides power to the electrical system when the engine is running. If it fails, the battery will eventually run out of power and the Jeep will die.
What Causes a Car Battery to Keep Dying? Some of the most common reasons for a car battery to die repeatedly include loose or corroded battery connections, persistent electrical drains, charging problems, constantly demanding more power than the alternator can provide, and even extreme weather.
Contrary to its purpose, an alternator can drain a battery. It`s rare, but it`s possible. A draw on the battery only occurs if there`s a problem with either a component in the alternator itself or connections to it.
Electrical devices or lights left running, a defective charging system or alternator, and extreme weather are some common reasons but maybe it`s just time to get a new battery.”
If you know your battery`s good and there`s no obvious reason it`s dying, the alternator and charging system could be at fault. When alternators fail and need replacement, the battery won`t stay charged for long.
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.
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.

Using a test switch and digital ammeter is the simplest, most accurate way to measure parasitic drain directly. A test switch goes between the negative battery terminal and negative battery cable.
That can be your car headlights, dome light, light in the glove box, or trunk light. Even vanity mirror lights can drain a battery if left on overnight.
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 most common causes of excessive parasitic drain include faulty relay switches, malfunctioning alternators, damaged wiring or connections, and electronic devices left connected or powered on when the vehicle is off.
Parasitic Drain

A small amount of parasitic drain is normal and expected, since things like your clock and audio system need some power to avoid being reset every time you turn off the car. However, excessive parasitic drain can be a problem, leaving your battery empty by morning.

Typically, a vehicle will start and then quit because of an issue with the fuel or electrical system. It is important to monitor fuel levels as well as warning lights which can signal to the driver that a vehicle may quit unexpectedly.
How long does a car battery last in my Jeep? The average car, truck or SUV battery should last six years.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I got a new battery new alternator put in but my battery just gets drained I keep having to buy new batterys
ANSWER : This may be a sign of a failing voltage regulator or potentially a bad grounding problem causing a draw on the system. The voltage regulator is a unit that regulates the charging of the battery by the alternator. Often times this will 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 either case, I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.

Battery Keeps Dying
ANSWER : There are three possibilities, to start with: 1) there is a voltage drop in the wiring between the alternator and the battery; 2) the "parasitic" power draw occurs while the car is running, not so much while it is off, thus overwhelming the alternator and consequently the battery is not being fully re-charged; 3) there is a parasitic power draw when the car is off but to pick it up requires data logging. With regard to these possibilities, if you desire that the required diagnostic steps be performed by a certified mechanic, please simply request an electrical circuit/charging system diagnostic. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

my battery kept draining until i bought a new alternator and battery. i have tightened the belt on the alternator but it still die
ANSWER : Hi there. The best way to diagnose why a battery would constantly drain is to review it’s job and how it is recharged. The battery is responsible for powering all electrical systems until the vehicle is started. At this point, the alternator takes over and also continually charges the battery while the vehicle is in use. A battery will drain when one of two things occurs. First, a battery will drain if it is constantly in use; supplying power to an electrical component even if the key is not in the ignition. Second, the battery will eventually die if the battery is not being charged frequently. However, since this is happening every two days, my initial thought would be that some electrical component on your 86 Olds is continuing to draw power from the battery. This is known as a parasitic drain. The best way to determine the source of this battery issue is to have one of our professional mobile mechanics come to your location and complete a battery will not hold a charge inspection.

Car battery light on… New battery and alternator but keeps dying
ANSWER : Hello. If your charge indicator is on, this indicates a problem in the system. The charge indicator will have a resistor that is about 390 ohms when tested and if it is bad then may cause light to come on. You are having a possible charge problem with alternator. A junk yard alternator may be bad and you would not know it until it is installed. You should have the complete charging system diagnosed by a qualified mechanic that will be able to go over the entire circuit.

is the ecm the problem if battery light is on and the alternator isn’t bad
ANSWER : This is likely a sign of a failing voltage regulator. This is a unit that regulates the charging of the battery by the alternator. In your case, it sounds like the voltage output from the alternator may be much too high resulting in overcharging the battery and burning up wires in the process. I would recommend having an expert from YourMechanic come to your location to diagnose and properly test your vehicle’s charging system.

Battery keeps dying for no apparent reason
ANSWER : Hello. If the battery and alternator are fine then I would test the ignition switch. It will commonly stay on and cause this. If it is fine, then an amperage draw test needs to be done on the vehicle. If all of the electronics are stock, then the issue may be a sticking relay. I have had the main fuse box fail internally and cause this a few times on this vehicle and the amperage draw test will identify this as the issue. If you need to have this looked at, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose your battery.

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.

Battery keeps dying and is corroded. Is it the alternator or the battery?
ANSWER : The corrosion may have an impact on how well the battery connection transfers the charge from the alternator. It is also possible that you may have a faulty alternator or a weak battery that is not able to take a charge. As you may know, the alternator is responsible for charging the battery while the engine runs by generating amperage and recharging the battery while the engine turns the alternator. The voltage regulator is a unit that regulates the charging of the battery by the alternator and maintaining a certain amperage while the engine runs. When the alternator is not working properly, this may result in the battery quickly losing charge and the car losing all power as you have described. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your charging system.