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Car Stereo Draining My Battery [CAUSES & SOLUTIONS]

How Can I Tell and How Do I Fix It?

If the amperage draw of your car battery is more than 0.85mA when the engine and every car accessory are off, it shows that your stereo is draining your battery. If you have a powerful aftermarket audio system, you can get around this problem by installing a powerful replacement of the stock alternator.

If you notice that your battery is struggling to provide power to car lights and stereo at the same time, it is a cause of concern. Especially, if the battery is well within its prescribed operating life, the car’s alternator is working fine, and you haven’t kept the car lights on overnight.

It strongly suggests that your stereo system is drawing continuous amperage from the battery. However, you need to be 100% sure that your car battery is getting drained before taking any action.

To help you out in troubleshooting and fixing this problem, we have put together this article. Here, we will discuss how you can tell if your car stereo is draining your car battery. Subsequently, we will also shed light on how you can fix this issue.

Things You Will Need to Find and Fix Car Stereo Draining Your Battery

  • Multimeter
  • Replacement alternator

How to Tell If the Car Stereo Is Draining the Battery

After identifying the initial symptoms of the battery getting drained (flickering light, stereo abruptly switching off, etc), you need to measure its amperage draw to be certain. Follow these steps to measure the amperage draw and to be 100% sure that your stereo is draining your car battery.

  • Take your multimeter, set its dial on the amp, and keep it at its max reading. It will prevent any damage to the meter due to any voltage/current surge.
  • Switch off the engine, shut the doors, and make sure every light and other electrical accessories of the car is turned off. Once you are sure that no accessory and component is drawing the current from the battery anymore, open the bonnet and remove the cable connected to the negative terminal of the battery (the black one).
  • Now, very carefully, touch one probe of the multimeter to the negative terminal cable and the other probe to the corresponding battery terminal (from where you have removed the cable).
  • If the multimeter shows a reading that exceeds 85 mA (0.08A), it confirms that your car stereo is responsible for your battery drain.

How to Fix Battery Drain Caused by a Car Stereo

Denso 210-0657 Alternator

More often, a car stereo drains the car battery when it uses a powerful aftermarket amplifier and set of subs. Their amperage requirement exceeds what the stock combination of an alternator and battery can provide.

In such a situation, you have to replace your stock alternator with a powerful upgrade.
A powerful alternator will ensure that you can keep on providing sufficient power to your beefy aftermarket amp and subs while simultaneously getting your battery charged.

Usually, stock alternators produce 80-100 amp draw, depending on the car model. Suppose you have an 80A alternator with 1000W RMS stereo, you will eventually face battery drain. You can get around this issue by replacing the 80A alternator with, say, a 130A alternator.

There is no doubt replacing an alternator is a costly affair. It can cost you around $300-500. However, this one-time cost will save you from the expenses of frequent battery replacements and the hassle of time-consuming battery charging. With a power alternator complementing your powerful stereo system, you can enjoy your music all the time without worrying about draining the battery.

However, you need to be sure that you need an alternator replacement. If you are using a regular amp with 300-400W total RMS but you are still getting your battery drained, you don’t need an alternator replacement. Instead, it points towards some complex issue for which it is better to go do an expert auto mechanic.

Vincent Talbot

Last update on 2021-06-15 / Affiliate links / Images from Amazon Product Advertising API