Q: Battery/Alternator - 2008 Toyota RAV4

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One day I noticed a different sound coming from engine. It was a low hum sound. It was not super loud or distinct I just noticed it was unusual. Not long after battery light came. The next few times I would start the car sometime I saw the battery light and heard the noice-others time the car was working as normal (no warning light/noise). I usually drive my car for short distances. 10-15 minutes trips are normal so maybe the battery is not getting enough charge. The car was operating normally and I ran some errands. On my way to my second stop, the power steering dropped out. Many warning lights turned on - such as VSC, battery, check engine, oil light and steering. This leads me to believe it is an issue with the alternator. I parked the car and turned the engine off. The car would not start again. I used a battery jump to recrank car. The car would start but would not stay on. I attempted this a couple of times. There is lots of corrosion on the battery also.

My car has 90000 miles.
My car has an automatic transmission.

The battery and charging system should be evaluated first. However, if your battery is more than 5 years old, I would simply replace the battery outright before doing further diagnostics (which are still needed). Batteries are actually critical components of vehicles, even much more so these days due to the proliferation of electronics in vehicles, and the fact that some components are very sensitive to voltage disturbances.

To work properly, the battery has to not only supply the right voltage, but it has to supply enough current to all the devices in your car (ignition, HVAC, lights, etc.) without excessive voltage drop. So you could have an old battery that has problems. But even if you "simply" replace an old battery, the mechanic will check the output of your charging system of which the alternator is just one component. So, initially, yes you appear to have an electrical problem and the initial points of concern are the condition of the battery and whether your charging system is functioning properly.

If you would like to have this resolved, consider YourMechanic, as a certified technician can come to your car’s location to diagnose the charging system and have this problem addressed.

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