How do I fix a parasitic power drain on 2018 Mitsubishi Outlander Sport

Question

I am reaching out desperately looking for help. I purchased this vehicle in April of 2022 and have been through 5 batteries. I tried contacting the dealership and they told me that the battery wasn’t in contract with my warranty plan. I have been to 3 mechanics and have been quoted anywhere from $400-$1200 for a DIAGNOSTIC ALONE. I am young, broke and trying to learn about cars but I am at a loss for what this problem is. I have been told, after testing my battery life and running codes on my car that no one can find where this power drain is coming from. I can’t afford an expensive fix and I just want to try fixing this at home. I was told that it could be coming from my backup camera, my center console screen or my dash screen. Although everything seems to turn off when the car is off, I cannot find where this drain is coming from. I don’t leave chargers or cords plugged in and I even have it set so that my cabin lights stay off when I open my car doors. If anyone has any insight or maybe some tips on how to disconnect my rear camera and/or my display screens (even if it’s a video link for YouTube), I would greatly appreciate it. I have been searching for over a year now and I genuinely cannot afford to pay all of that money for someone to MAYBE find the drain. Also, I have very VERY limited knowledge on cars, so bare with me, I’m trying to educate myself the best I can. Thank you so much!

Answer 1

The first thing you need to do is obtain a clamp on amp meter. If you can't afford one, hopefully someone you know has one you can borrow. Without an amp meter, you won't be able to tell anything. Once you obtain the amp meter, you can put it on your battery cable and see what the amp draw on the battery is with the vehicle off. The typical draw for a vehicle with the ignition turned off should be 50-85 milliamp. That's not a lot of draw. If your current draw is in this neighborhood, then you have other issues. If it's way over this, then read on.

Next, locate your fuse boxes. You should have two of them. One under the hood (bonnet) and the other inside the passenger compartment, usually under a panel in the dash to the outside of the steering wheel. Start with the one in the engine compartment. Methodically remove a fuse and check your amp meter for a difference in draw. Continue doing this until you either find the circuit which is causing the issue, or you've gone through all the fuses. When done with the engine compartment one, do the same for the passenger compartment fuse box. One (or more) of the fuses should lead you to the circuit where the draw is located.

Once you've located the circuit, then you need to figure out what is on that circuit and which item may be causing the draw. The usual suspects for high draws are aftermarket parts. If the stereo head unit has been replaced, this is a good place to look. If the vehicle has an aftermarket amplifier added on, it could be it is "on" all the time, even when the stereo/ignition is turned off. You'll have to dive deeper at this point to actually narrow down what is causing the issue, but the circuit should give you a pretty good idea what is causing the drain.

Once you've located the drain, you'll have to figure out what you want to do about it. It could be caused by someone miswiring something. It could just be faulty equipment which needs to be replaced. That is going to be up to you.

Something you might do in the meantime is to get a battery tender (not a trickle charger) and install it on your vehicle. This will allow you to keep the battery charged while the vehicle is not in use. They are relatively cheap as you can get one for ~$20 here in the States. This isn't an "end all" solution, but should get you by until you can trace down the offending gadget causing your issues.

Answer 2

I've been thinking about this subject lately, and had some ideas about how to go about troubleshooting. The clamp-on amp meter was my first thought, but I wasn't sure if they read DC current. It seems the more expensive ones might, but they might be designed for higher currents. So, I thought of a better idea, I think. I already have a multi-meter, which can measure up to 10 amps of current, connected inline rather than clamped on. So, although not nearly as easy as a clamp-on, it's not that hard to use a wire with clips on each end, and connect one end to the battery and the other end to the connector after removing it from the battery. It might even be possible to connect it before disconnection, to avoid losing the car settings. The multimeter is much cheaper than clamp-on DC amp-meters, and pretty useful to have.

If excessive current is detected, my next step would be to use the volt meter to check voltage at each fuse. Any fuse that has 12V should be removed, and the current tested through that fuse's connectors. Checking for 12v first will avoid the need to remove every fuse, since most of them are not live with the ignition off.

One question for experts... can the initial test be done using the negative terminal of the battery connection? Seems like it should be the same from my basic knowledge of electricity. If so, it would be easier to keep the system alive while disconnecting and reconnecting the terminal by clipping a wire from a car ground to the battery cable first, then connecting the meter and disconnecting that wire to get a reading.

tl;dr... instead of using a clamp-on meter that usually doesn't measure DC current, and is expensive...

1. Disconnect one lead to the battery;
2. Connect regular multimeter on DC Current function between the battery and the lead;
3. Measure current using multimeter. Ideally, this should be less than an amp, but it probably depends on the car. Ideally, it would be very near zero.

If the current is too high, the first line of troubleshooting would be to check for voltage at each fuse, and any fuse that has 12V, remove the fuse and check current with the multimeter at each side of the fuse connections.