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My 2013 was hard to start yesterday when I was going to go on a shopping run, so I stopped by the auto parts store and had them check it. 260 CCA from a battery rated at 490. Obviously time for a new battery...but they didn't have the right ones in stock. So I went to Sams Club to get this:
https://www.samsclub.com/sams/duracell-automotive-battery-group-size-25/prod3590214.ip?xid=plp:product:1:1
which we got for our 2012 a few months ago. Its the same battery size (group 25), but much higher CCA.

Sams was pretty backed up (multiple cars ahead of me getting tires and only one tech...and they'd only just opened! But I'd planned ahead and brought tools, so I told them just sell me the battery, and I'll do it myself in the parking lot so I don't have to come back to turn in the core.

Replacement went relatively hassle-free. When finished, I went to start the car and leave, and the car would start, but the engine would die before I could even get it in gear. I did this several times, and it just wouldn't run. I started to get worried...not sure what I could have screwed up that it would have power, but not run. I tried one more time, but instead of just sitting with my foot on the brake, I gave it some gas as soon as I started it and kept the RPMs up around 1-2k for maybe 10-15s. That seems to have gotten it past whatever its issue was. A friend I'd called who used to build race cars thinks the ECU probably just lost its memory, didn't know how much gas to feed the engine, and needed some time running to reestablish its grip on reality.

Is this a common thing? I've stood there with the person at the parts stores while they replace the battery in other cars, and can't remember ever having trouble getting the car running after the change.
 

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2014 OBW Premium (Ice Silver Metalic)
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309 Posts
I think your friend's opinion that the ECU lost its memory is spot on. All should return to normal after a few drive cycles.

Some stores use a power supply that plugs into the OBD2 port. I've seen this practice blow the fuse to the ECU. I like your problem better.
 

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2013, OB Limited, 2.5, dark gray. July 2016 - approx 55,000 miles.
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Well timed for me. We've a 2013, and as it's 4.25 years old and we're moving to Utah, I was going to replace the battery (I don't want it to give my wife issues, and it'll live outside the first year). I see there's also an ''ultra'' version of this battery, looks pretty nice. $125 for this.

 

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'14 Subi OBW, '18 Subi Forester
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The full technical answer is that today's cars lack a separate Idle Air Control which bled in just enough air for (you guessed right...) idle speed. Modern cars use a carefully modulated positioning of the main throttle plate instead, and dispensed with the separate channel. But that tiny air gap of the main plate changes over time as the plate builds up crud, etc., and the ECU compensates by changing that position and recording it in memory.

When you wiped it out by removing the battery, your ECU forgot the last position, and went back to factory default. Default was far too closed for your aged (and no doubt getting dirty) intake to run, so it kept stalling.

Yes, I use a home built 12v, 1 amp regulated filtered power supply to keep my ECU alive when removing batteries.
 

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2013 Outback, 2.5i Limited w/ Moonroof
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Well timed for me. We've a 2013, and as it's 4.25 years old and we're moving to Utah, I was going to replace the battery (I don't want it to give my wife issues, and it'll live outside the first year). I see there's also an ''ultra'' version of this battery, looks pretty nice. $125 for this.


Wait until you get here to Utah to replace your battery.

Car batteries are made for different climates. Batteries sold in Southern states are made for warmer climates. Batteries sold in Northern states are made for colder climates.
Perhaps the batteries in Northern California are the same as here in Utah, but just in case, I'd wait until you get here.
 

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2014 Outback Limited 2.5im 2012 Impreza Limited
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74 Posts
Yes, I use a home built 12v, 1 amp regulated filtered power supply to keep my ECU alive when removing batteries.
Where do you connect your power supply? I've thought of doing the same thing with my battery charger, but it is a newer digital type that would sense the absence of a battery. I suppose I could use the battery out of my riding mower as a temporary power source. Thanks.
 

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'14 Subi OBW, '18 Subi Forester
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Note that I said 1 amp regulated! It's designed with a IC component that decreases the voltage if the circuit attempts to pull any more current than an amp. That's the safeguard that nothing will be damaged. Battery chargers or other batteries in this application is like playing with fire (figuratively mostly, literally in the extreme).

I'm clipped to the chassis (negative contact) near the oil filter, and to the alternator stud (positive contact), and monitoring voltage as I work. Battery terminal connections are held with green insulated wire out of the way.
 

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