(Updated on November 11, 2020)
The alternator serves a very important purpose in your vehicle. It is responsible for generating the proper amount of electricity for powering the vehicle’s electrical components and battery.
The alternator is able to generate this power by converting the vehicle’s mechanical energy into electrical energy. If you have a bad alternator, then all your vehicle’s electrical components would need to depend on the battery for power.
Unfortunately, the battery is not powerful enough to provide the proper amount of electricity that these components need. The car may run for a couple of minutes before the power dies. That is why a functioning alternator is a must for any vehicle.
Common Causes of Alternator Failure
When people experience electrical issues with their vehicle, they’re quick to think it’s the battery’s fault. But if you have a newer battery and you’re still having these electrical problems, then it’s likely the alternator that is at fault.
Below are five common causes for an alternator to go bad.
1) Dead Alternator
This one’s pretty obvious. The typical lifespan of a new alternator should be between 5 and 8 years. If it has been that long and you have electrical issues, then your alternator may simply be worn out and needs to be replaced.
If you think it could be your battery that is at fault, the typical lifespan of a battery is between 2 and 5 years. Environments that are usually hot will drain the battery power quicker, so it may be 2 years for you in these cases. The temperature shouldn’t affect the alternator, though.
Related: Symptoms of a Bad Alternator
2) Computer Problem
Newer vehicles are built with computer systems in them such as the ECU. These systems are what manage virtually every component of the vehicle, including the alternator. If there were to be a problem or glitch with the computer system, it could stop the alternator from charging properly even if it’s a good alternator.
Chances are there’d be other issues that would arise from a computer problem too. That’s how you would know that was the cause.
3) Wiring Problems
There are lots of wires in the vehicle which deliver power to the alternator. If one of these wires were to become damaged or worn out, then it could cause the alternator to fail at its job and the battery to not get charged.
If you don’t see any of the other problems on this list being present in your vehicle, then check the wiring of the alternator because that may be the reason for the alternator not working.
4) Bad Fuse
Vehicles use fuses to keep the alternator functional. These fuses blow out after a while or when there is a power surge. In these cases, your alternator would fail and your battery would not charge.
If you have a bad alternator, look in the owner’s manual to see where the alternator fuse is in your car and check to see if it is blown.
5) Broken Pulley or Broken Belt
Alternators use the mechanical power of a belt and pulley to generate the electrical energy for the vehicle. The problem is that the alternator belt and pulleys are not too durable, which means they can easily break.
Pulleys will typically last for a long time before they eventually get damaged from old age. Belts are flimsier and will eventually start to crack and even break after enough time. If either one of these things were to happen, there would be no mechanical energy being generated for the alternator to convert.
the altenator is locking up put a brand new one on locked up as soon as i started the car its a jeep cherokee 2007.
I have a 1999vw golf I changed the altnator and it ran good for about 40 mins now what
What were the symptoms that led you to change the alternator?
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Can you please elaborate? I’m not sure what you mean.
I have changed 3 new altenator in 4 wks in 2010 dodge avenger what can be my problem
The root cause is probably not the alternator. What led you to change the alternator in the first place?
I am having this issue with dodge avenger also went through 2 alternators in 1 week no idea what this is ? Battery light came in randomly alternator does battery then does replaces both and not 3 days later alternator dies again.
I have a Santa Fe 2007 with automatic transmission, yesterday after a smooth brake I felt something happened in the car and then after a few km the car suddenly stopped fortunately close to the parking place and I just managed with several time use of jump starter get it to the parking. I saw that the tail lights won’t turn off while the car is turned off. Or I can not turn off the front window heating when I start the car with jump starter. it is not a stable electrical system since this happened and the mechanic said change the alternator. It seems that alternator not working but I am almost sure there can be other root causes. Do you have any idea?
If the alternator tested bad, I would start there.
Excessive jump starting can sometimes harm the electrical system of the vehicle. It’s possible the surge from one of the jump starts blew a fuse somewhere.
The pulley and shaft of the alternator on my Volvo XC 70 came out requiring a new alternator. The belt did not break. I had had a new belt fitted (by dealer) three weeks before – could it be that the new belt had been incorrectly tensioned?
I don’t know. I suppose it’s possible, but that sounds like an alternator defect not incorrect belt tension to me. Was it still covered under warranty?
Well was told my Alternator blew and it blew the cars motherboard. After ready this I wonder if it might have been the opposite way around. The car was arrived by the dealer two weeks prior just 4 yrs old and had done only 10,100k. I would consider that practically brand new
I meant to write serviced at the dealership
I would be wary of anyone who calls the ECU a motherboard, personally. Maybe they were just trying to make the diagnosis easier to understand, I don’t know.
My alternator failed in my 2010 Honda CRV about a month ago and we had to get it replaced. It looks like the replacement one just failed as well. I’m not sure what’s causing them to break, but I think it has something to do with the rattling that can sometimes occur when accelerating. To get the rattling to stop you have to take your foot off the gas for a second. Could this be a belt issue?