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11-07-2023, 01:43 PM | #1 |
Scooby Newbie
Member#: 142375
Join Date: Mar 2007
Location: SLC
Vehicle:2019 STI |
New to me STI - Battery Drain?
Hi,
I've got a new to me 2019 STI as more of a hobby car at the moment, still driving my Outback more often. I let the STI sit for about a week in the garage and the battery was dead when I went to start it. Do I have a battery drain, or do these newer cars and their electronics need to be driven more often than once a week to charge the battery? If so, sounds like I need to use a trickle charger. I feel like a week is not that long to drain the battery completely but maybe so.. Thanks!
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11-07-2023, 02:08 PM | #2 |
Trust no one
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Vehicle:02 RAV4 MT 15 WRX/11 CRZ |
Should last more than a week if the battery is fully charged to begin with.
First thing to do since you just got the car is to charge the battery and have it tested, it could just be weak after 4+ years. If there is still drain with a known good battery you can do a parasitic drain test by connecting an ammeter in series with one of the battery terminals. After allowing time for everything to go into standby mode the drain shouldn't be more than about 50ma or so. If it's much higher you'll need to do some troubleshooting to find where the excess drain is. Start with obvious stuff like the trunk light. |
11-08-2023, 05:18 PM | #3 | |
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11-08-2023, 07:02 PM | #4 |
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Do you pay for Starlink? I'll assume no because nobody does. There is a fuse in the engine compartment called DCM. Pull it and put it with your spare fuses. This is a common problem with Subarus because the Data Communications Module spikes current once a second, always. This fuse feeds nothing else. Even if this isn't the problem, it's a problem.
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11-09-2023, 09:14 AM | #5 | |
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11-13-2023, 09:36 AM | #6 | |
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Either way, thanks for alerting me to this - it sounds like a known issue but no real fix except for having a dealer perform an update. I'll explore that route. |
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11-13-2023, 05:01 PM | #7 |
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Interesting. I did this following a South Main Auto youtube video. But he was doing a 2017 Subaru Legacy and that's what my wife has. Perhaps find the Data Communications Module and unplug it. I have no idea where it is. In the video, he found in the wiring diagram that in the Legacy, nothing else was tied to that fuse. I'll have to see what happens in my son's STi. I did it in my 19 Crosstrek and it's been fine.
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11-13-2023, 08:43 PM | #8 | |
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Quote:
Last edited by Fast03Wagon; 11-13-2023 at 08:44 PM. Reason: spelling |
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11-13-2023, 08:50 PM | #9 |
Trust no one
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A lower drain is good. I gave 50ma as a somewhat arbitrary number for what would be considered nominal, with a much higher value being cause for concern.
Still a good idea to get the battery tested so you can rule it in or out as a potential cause for the drain. It's also possible that the drain isn't constant and goes higher at times for things like what Jack mentioned or something else. But, without a way to record the current over time it's hard to tell. |
12-03-2023, 09:55 PM | #10 |
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Hope its just the battery getting weaker.
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12-04-2023, 06:59 AM | #11 | |
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BTW: Unplugging the DCM will kill the front speakers as well - the front speakers are wired from the radio through the DCM. |
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12-04-2023, 08:18 AM | #12 |
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Elbert is correct, I should have mentioned that step.
However the drain will generally be higher initially until everything goes to sleep, so if you did actually see 7.5ma upon connection it's probably ok. You could certainly repeat the test again and use the stated procedure. |
12-04-2023, 05:08 PM | #13 |
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Anyone know how to fix this problem on a 17 sti, there is no dcm or telematics fuse listed in the manual? I've also had the battery tested and its fine.
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12-04-2023, 05:49 PM | #14 |
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You would be amazed how many times I would find the trunk/cargo lamp turned on in cars that came in for a persistent battery drain...
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01-30-2024, 03:21 PM | #15 |
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Please tell me, could the battery have failed within two years? Since I replaced it, it discharged completely once but worked after charging. Lately, if I don't drive for at least 3-4 days, it starts as if it's severely discharged for the first time. I suspect there's a discharge, but I haven't figured out where yet.
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02-20-2024, 09:33 AM | #16 |
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To update this thread, I bypassed the DCM unit with this:
https://www.autoharnesshouse.com/69018.html It solved the battery issues for me and keeps the front speakers and microphone working. Now I can start the car after a week+ of sitting in the garage no problem. |
02-21-2024, 09:03 AM | #17 | |
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03-05-2024, 10:16 PM | #18 |
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I have a '21 and my battery will also die after letting the car sit for 1-2 weeks. Not sure if its a normal thing. Seems like it's rather quick for it to die
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