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I'm not sure, but I seem to be having a battery issue with my 2009 impreza.

 

Over the holidays I took a day to thoroughly clean out the inside of the car...which of course requires the door to be opened for an extended period of time. I turned the dome light off after the first hour while I did this, but inadvertently forgot to completely close on the the doors all the way for the night (dome light is still off). The next day the car wouldn't start. All the lights came on then I put the key in the ignition, but the starter just turned over weakly and wouldn't start the car. I thought it was odd. There were no battery lights or anything. I was able to jump start the car and drove into town 50km away. The car started fine for that day. A few days later I took the car on a very short trip where it started well enough, but later in the day it again didn't want to start....same symptoms...the starter is turning over but the engine isn't firing up. At this point I took the car to a local car parts store where they tested the battery and alternator. Turns out the alternator was putting out the correct voltage, but the battery wasn't holding a charge. Ok, great....problem solved. I got a new battery and went on my way. I still thought it was odd for a 2009 to have a bad battery already though.

 

Fast forward today.....car didn't want to start this morning. Same symptoms. Lights came on when I put the key in the ignition but when I tried to start the starter just turned over weakly for a short time before finally starting. I don't take a lot of short trips and my daily commute is 50km each way so lots of opportunity for the battery to charge.

 

This seems like the same problem I had before....any ideas what could be running my battery down, or not charging it fully or properly?

 

Thanks!!

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Sounds like you have an electrical drain somewhere.

 

Any aftermarket electrical items installed?

 

Need to check for a drain, sounds like something is draining the battery. Remove the positive cable and put a multimeter between the battery post and cable end and see how many milliamps it's pulling with the key out of the vehicle and nothing on. Somewhere very roughly around 50 milliamps is normal. If you have hundreds....you have a drain.

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The only thing I installed on the car was some LED lights to help light up the back hatch when the trunk opens. They plug into the little factory light that's already in the hatch. These were installed after the first round of battery problems though.....so I don't think they're the cause.

 

Are there any known culprits that will cause battery drain that I should check out first? What about the stock security system?

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around here, batteries are suspect at 3 years of age. they are getting old at 2.5 and rarely last over 5. But cooler locales should be able to get a longer lifespan if the battery is not abused.

 

Any complete discharge of a typical auto battery will usually decrease its lifespan as well so, it isn't out of the realm of possibility your battery was bad, and evidently that was indicated at the parts store.

 

Still, worth doing the test outlined above on parasitic current drain.

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I'd have the alternator tested again too. Maybe it's frying the batteries or otherwise taxing them somehow? Low mileage/age for an alternator though...

 

Might even ask the local store that tests alternators and batteries if they can test for a drain - I think some of them may be able too with their testing stations that can be rolled out to the car and everything tested on the vehicle instead of in the store.

 

Can't think of any common issues, Subaru's aren't known for drains/wiring issues.

 

On a car that new, it's often the case that it's just an oddball issue that needs tracked down.

 

They tend to crack insulation where the wiring for the trunk pivots up and down...over time cracking insulation, exposing wire, etc. I've seen it more on the hatch/wagon versions than a regular trunk, probably longer range of motion. But that is unlikely with such new and low mileage vehicle. Usually you'd have other symptoms too - like lights not working, etc.

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Check the voltage across the battery posts while the engine is running around 1500 RPM with the headlights on high and the blower on high also. If you have heated seats turn them on also. You should see at least 13.4 volts at the battery. Also check the AC ripple voltage, that should be less than .1 volt if the diodes are ok.

 

Checking the current drain with all systems off and in the sleep mode you should have less than 25 milliamps of current drain from the battery.

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Ok, I have a few more notes to add to this trouble shooting issue.

 

After having trouble starting the car this morning, when I arrived at work I switched the headlights off .... which I normally don't do as they turn off when the car is off. When I started the car after it sat at work for 11 hours and with the headlights off it started without too much trouble.

 

My drive home was through a snow storm and as all the snow made the reflection off my headlights so much more noticeable I also noted that there was some intermittent flickering in the headlights while on the drive home. It wasn't severe, but it was there.

 

I parked in front of the barn and revved the engine while watching the headlight reflection off the side of the barn and again noticed some intermittent flickering. It didn't seem to be directly related to engine revs, but if you looked for it it was definitely there.

 

Does this indicate that my alternator on the way out??

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Turning off the light switch shouldn't make any difference as far as I know of since all the power to the lighting circuit is cut off with the ignition switch. It does sound like there may be some bad diodes inside the alternator causing excessive ripple voltage and you see the results of it in the lights. It may also be that the alternator is causing excessive current drain to the battery due to that same problem. I think you are going to have to replace the alternator.

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