A Woman Replaced Her Car's Battery 3 Times In 1 Year Due To This Power-Draining Culprit

Some car issues can be really easy to diagnose, like a failed bulb, for example. Just put the lights on, walk around the car, and see which isn't working — easy! However, some issues can prove to be a real nightmare to diagnose, and parasitic battery drains are among them. A parasitic battery drain is when something saps away at your battery's power while the car is off, meaning the next time you get in the car, it might be completely dead. This leaves you forever relying on jumper cables and replacing batteries more frequently than you would normally. The culprit could be anything from damaged wiring through to an aftermarket radio or faulty sensor.

Well, this is exactly what one woman was experiencing with her 2019 Toyota Tacoma. Frustrated that she had replaced the battery three times already within the space of a year, she booked it in to be cured, having seemingly identified the issue as a faulty tire pressure monitoring sensor for the front left tire. As it happens, her diagnosis was wrong, but fortunately the technician was able to identify the issue fairly quickly.

He first ran a parasitic draw test, which revealed a draw was being taken from somewhere. He then clocked a flashing dongle down in the driver's footwell, which was plugged into the OBD-II port. Such devices are typically used for diagnostic purposes. He promptly removed it and then returned to his multimeter, which almost immediately confirmed that the parasitic draw had disappeared. Perhaps rather embarrassingly, it was the owner's own device, which was causing the draw, and costing them a small fortune in battery replacements.

The frustrating thing about parasitic battery drains is that almost anything can cause them. However, there are a number of causes which are more common than others, and starting with the simple stuff is always the best approach.

If you've noticed your battery running flat, start by checking the basics — have you left your lights on perhaps? It could be something obvious like your headlights, or something less obvious, like an interior light, or even a little light shining if your glove compartment is left slightly open. If that's not the culprit, take a moment to think about how old the battery itself is. If it's over five years old then the chances are it could just be time for a replacement, and extreme weather won't help either, so if you're experiencing the issue during the midst of winter, there's another likely clue that you should replace your battery.

If your alternator has failed, your battery won't charge while you're driving, which might leave you reaching for those jumper cables once more then next time you hop in. There are different ways to tell if your alternator is bad, if you don't feel like paying a technician to diagnose the issue for you.

Finally, an extremely common cause is something you've done. Be it installing an aftermarket radio or plugging in that dongle to your OBD port, if you notice a battery drain after installing something aftermarket, then that would usually be the best place to start. A multimeter is a cheap piece of kit, and with one, you too can perform a parasitic battery draw test like the technician did on the aforementioned Tacoma, which will reveal when the draw has been removed, or whether one exists at all.