Nope not necessary.

 

The situation with having to do a bunch of resets is definitely better than it was. And yet pretty much monthly we have a member post some kind of issue they had after disconnecting power. It's usually not too annoying, but some SK vehicles take some work to get straightened out.

You can take your chances, and likely you'll be OK.

I'm an old-school electrical engineer with automotive system debug/prototyping experience, so I still hook up a little 1 amp power supply to keep everything minimally juiced up any time I disconnect a battery.

 

What is the best way to supply the 1 amp power? Is there a simpler way than the one mentioned in the video? I have a portable car jumper with alligator clamps. They clamp on the battery terminals to help start the car but I'm wondering if can I clamp those to the terminal wires after removing them from the battery.

Worried I'd screw things up worse than just doing it the old fashioned way!

 

Car jump starters provide a LOT of amps, and, while it would work if you could keep the clamps on the battery cables as you switched batteries, it would be VERY easy to accidentally create a short. With the amperage available from a jump starter, that could be dangerous. Not just physically to whoever is doing the battery change, but to the ECU and other computer parts in the car.

So, don't do that.

If you have a small trickle charger, you could use that. Again, though, keeping it attached to the battery cables as you swap batteries is problematic.

I don't know how much it changed between the SJ and SK models, but there really aren't that many things that you have to manually reset after a battery swap. Mostly the clock and some of the alert settings on the dash for my SJ. Yeah, the ECU loses some settings, like emissions testing readiness, but those reset themselves within a few drive cycles in most cases.

A quick search on Amazon shows that those "keep alive" tools are available to hook up a 9v battery, 8x AA batteries, or even a USB portable power supply if you don't have a spare 12v battery available. Don't bother with the ones that plug into your cigarette lighter/power port, as those are disconnected when the car is turned off.

 

When I removed my battery for spark plug change, had no issues after replacement. But look at this. Several people have damaged the sensor on the negative cable.

 

Thanks, will pay attention to it.

Car jump starters provide a LOT of amps, and, while it would work if you could keep the clamps on the battery cables as you switched batteries, it would be VERY easy to accidentally create a short. With the amperage available from a jump starter, that could be dangerous. Not just physically to whoever is doing the battery change, but to the ECU and other computer parts in the car.

So, don't do that.

If you have a small trickle charger, you could use that. Again, though, keeping it attached to the battery cables as you swap batteries is problematic.

I don't know how much it changed between the SJ and SK models, but there really aren't that many things that you have to manually reset after a battery swap. Mostly the clock and some of the alert settings on the dash for my SJ. Yeah, the ECU loses some settings, like emissions testing readiness, but those reset themselves within a few drive cycles in most cases.

A quick search on Amazon shows that those "keep alive" tools are available to hook up a 9v battery, 8x AA batteries, or even a USB portable power supply if you don't have a spare 12v battery available. Don't bother with the ones that plug into your cigarette lighter/power port, as those are disconnected when the car is turned off.

Makes sense. Bought > https://www.amazon.com/gp/product/B07QV2QFTC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
Which lets me use the outlet or a 9V battery.

Forgot to mention that I am planning to use this product on the new battery which is supposed to help with battery corrosion.

 

Doors closed, lights off, hood open. Wait 20 minutes or so after ignition off for all microprocessors to go to minimum power state which should be around 75 milliamps or so. At that low you could run for an hour on a 9v battery and be OK, but I prefer a small regulated 12v power supply with a voltage monitor.

I connect using alligator clamps. You can connect the POSITIVE to the alternator main wire (goes directly to the battery) under the rubber cap, and the GROUND to any engine / chassis spot. Just stay away from the ECM module. This keeps all extra wiring away from the battery and battery wires where you are working.


As said above, you must insulate the positive lead that you remove from the battery. If it touches any ground metal it will short and plunge the voltage on a limited supply, arc something awful if you are using a big battery or the like.

Follow the TSB and don't break the voltage/current/temperature shunt assembly on the negative battery terminal, or you'll be taking a trip to the dealership for a replacement.

 

Bro why are my posts being deleted?

 

Your posts are being merged, not deleted. 😉
Immediate quotes were replaced with @ to the specific member.
More information can be found here:

https://www.subaruforester.org/threads/forum-rules-please-read.757081/?post_id=7252993#post-7252993

 

Any lead acid car battery has an expected lifespan of 3-5 years. They are consumables like tyres and do not last the life of a vehicle. Your 5 year old battery has had a long life, so you shouldn't be surprised and trying to claim from Subaru would be a waste of time.

 

I've put AGM batteries in all my Subaru's that started showing signs of a weak battery and never had any problems. After doing some research because of company changes in the battery-world, my latest was an Odyssey (available online and at AutoZone).

Here's a good article about different battery types in case anyone hasn't dug into the details recently.

The Differences Between AGM, GEL and FLOODED Batteries

Even though inside all AGM, GEL and flooded batteries contain lead acid, the internal construction of the battery divides them into their respective categories.Absorbed Glass Matte or "AGM" batteries are the latest and greatest in lead-acid batteries. An AGM battery uses a separator consisting...

batteryguys.com

 

I have a 2019 Forester Sport which has the auto stop start and EFB battery like yours. Here in Seattle we aren’t too bad on batteries but I got 5 1/2 years out of my battery and it was still going strong when I replaced it. I credit the long life due to
1) a Auto Stop Start eliminator to turn that silly thing off
2) Occasionally putting the car on the high quality battery maintainer (Optima 400).

I replaced the Subaru EFB with an Interstete AGM battery. Both in my Forester and my 2021 Crosstrek. Am super happy with them.

 

!⃝ Moderator Note: Merged Post

I followed these steps when installing a new battery.

1. Turn off the car, locate the OBD2 sensor. Plug in the cable in ODB2 port, plug the other end into an outlet.
2. Close the door and wait 20 mins.
3. Remove negative terminal cable taking care not to mess up the battery sensor.
4. Remove positive terminal cable and ask someone to hold away or tape it with electrical tape.
5. Replace the battery.
6. Reconnect the positive cable.
7. Reconnect the negative cable.
8. Unplug memory saver from the outlet.
9. Unplug from the OBD2 port.

However, I must've messed up somewhere because when I connected the positive cable, all was ok but then when I connected the negative cable, I saw some sparks.

I proceeded to connect the cable and unplugged the memory saver but not sure what to do next.

 

Is everything working? Interior lights working? Does the vehicle start?

Some sparking is normal when reconnecting the negative cable. You didn’t mention that there was a problem other than the sparking.

Most auto parts stores will provide free battery install with battery purchase. That it worth if for those that are not familiar with battery replacement.

 

I haven't tried starting the car yet. I also forgot the battery case when putting the new battery in. Should I undo everything or is it ok to skip?

The battery sensor under the negative terminal cable is loose now and I've broken the plastic cable holder (not my image) -

this is mine -

Thank you!

 

1. Battery sleeve can be left off. It’s there for a reason, so you might consider installing. I haven’t had a cover on the battery in my Impreza in over a decade, and I don’t have one in the Forester because the OEM sleeve doesn’t fix of the Interstate 24F battery I installed.
2. I’ve broken that plastic piece on every Subaru I’ve owned, unfortunately. It hold that harness in place, that’s all.

 

Whew! thanks for the feedback and sanity check. I've replaced batteries several times in the past (honda/toyota) but it's been a while and first time on Subie. I started the car and it seems to be working fine. Got a message to go in the settings menu. I don't rmr customizing it much so I think I'm good for now. Will see if I can gather enough courage to install the battery cover. Main concern is that the battery sensory is fairly loose on the negative terminal and the J hook between the battery and the air filter is not fun to deal with.

 

@savvyforester
Pls note from the rules: "5. Similarly, do not use "Reply" or "Quote" when responding to an immediately preceding post and/or the original post of a thread as we do not want to read stuff twice and it just clogs up the thread."

Use the "Write your reply" box instead

Thanks