What could be draining my battery? Any ideas?




It’s hard to tell for sure, but it could be the throttle body. I could be wrong, but I know the Focus has a lot of sensitive electronics. On the Focus, whenever the car detects the key nearby, the computer automatically runs a wake-up calibration test. It doesn’t matter if you have a physical key or a fob— the system still detects it. When the key is within range, usually less than 5 feet, the car starts waking up certain modules and actuators to get everything ready for a smooth start. Without this process, it would take longer to start the car every day. If your battery is already dead, I’d recommend taking it to a mechanic or dealership to diagnose it properly.

@Riley
Thanks for the input! I park in a garage at my apartment and tried starting it for the first time in weeks, so it shouldn’t have been sensing my car nearby. I’m planning to get it started (hopefully) and take it to a mechanic.

@Aza
If you haven’t started it in weeks, that’s probably why your battery is dead.

It looks like the throttle body to me.

Jordan said:
It looks like the throttle body to me.

Thanks! Any idea why it might be draining the battery?

It’s the throttle body in the picture… But it sounds like your battery monitoring system (BMS) wasn’t reset when the battery was replaced?

Cory said:
It’s the throttle body in the picture… But it sounds like your battery monitoring system (BMS) wasn’t reset when the battery was replaced?

I’m not entirely sure, but it only took about 15 minutes at the shop, and it worked fine for the rest of the day. Haven’t used it since then.

@Aza
Here’s a video explaining what the BMS does and why you might see strange behavior with your electronics if it’s not working right. Some shops may not have the tool to reset the system properly.

Are you sure your alternator is working properly? A bad alternator won’t recharge your battery.

Oaklan said:
Are you sure your alternator is working properly? A bad alternator won’t recharge your battery.

I’m not completely sure, but the mechanic said a new battery wouldn’t have drained in just a week. They said there must be something else draining it.

@Aza
Without a working charging system, a battery can’t run the car for a week. It might last 50 miles back in the day, but now with more electronics, it’s probably even less.

How did you figure out that this part is draining your battery?

Vic said:
How did you figure out that this part is draining your battery?

When I tried boosting the battery and the lights came on, this part started making a ticking noise, like it was trying to run.

How did you come to the conclusion that this part is draining your battery?

Dell said:
How did you come to the conclusion that this part is draining your battery?

When I go to boost the battery and the lights turn on again, this piece starts making a ticking noise like it’s trying to run.