grounds?

If there's a visible spark maybe you can have someone else try to locate it or set up a camera to video it?

 

I think your vehicle generation has had faults reported about the ignition switch assembly not always making proper electrical contact in the switch.

Try wiggling the key in the ignition when you have the problem to see if that makes any difference.

Seagrass

 

I would look very closely at the battery clamps. If they're original and questionable, change them. Clean the clamps and battery posts well; I like using a wire brush battery cleaning tool.
Be sure the clamps are pushed all the way down on the posts. Remember the battery posts are tapered so if the clamps are not fully down they will not tighten correctly even with the nut fully torqued.
Also check the other end of the battery cables, particularly the ground.

 

^ I'm with dukey. Very strong chance that this is just a loose, cracked, corroded, or otherwise compromised terminal clamp on the battery itself.

Remove the clamps from the battery, clean the clamps and the terminal lugs, re-set the clamps in position, remember to tap them down for good contact and then tighten the clamp nuts.

 

Engine compartment fuse box is just behind battery in that year, no? I'd check the main fuse. It may be arcing where it connects to a post, or the post may be arcing where it connects to the wiring underneath. To see the latter case you will have to remove the fuse and possibly the box itself so that you can look underneath it.

 

This is stereotypical bad battery connections, so definitely start there. Take the terminals off and clean them (buy a terminal brush if you don't have one). Inspect the post between the cable and the terminal. Put it back together, and seal it with some protectant. 90% chance your problem will be solved.

If it does come back, follow those cables and look for any damage on them, and the connections where they meet the fuse box, and grounds. You likely have some corrosion there.

 

All the above may be valid as any bad connection in the circuit could cause this problem, however, there is another one I have encountered before, and that may be a starter worn out out, or with a short in the wire, or loose wire connection.

 

Have 2020 Onyx Outback, no manual key, battery regularly showing 11.9-12.1 volts, alternator test shows good 14+ charging. Even after a good overnight charge, a day or two sitting has the battery below the preferred 12.5 voltage. I fear a total lockout as in an attempt to figure out a workaround since Subaru appears not particularly interested in addressing the battery issues without the class action suit now in progress....I thought if I charged the battery overnight, then left the hood unlatched I would at least be able to get to the battery for a jump if I was locked out/remote not unlocking doors due to dead battery....However, doing so then puts a warning light on the dash that the hood in unlocked, which of course becomes another constant electronic drain on the battery.... Bottom line, really bad engineering screw up, with no fix that I can see other than a separate type of cutoff of all draining electronics. If the battery dies, the remote only entry won't open the doors to even access the hood release to jump a battery....the 2020 Outback is a lemon recall just panting to happen.....So I suggest Subaru find a really sharp electronics nerd to save them from a total vehicle line buy back.

 

PS- before someone brings up the emergency physical key inside the large remote, several others have posted that when their batteries die, the physical key may not fully activate unlock mechanism. May be a picky issue, but there is no excuse from an engineering perspective for this dead battery issue, and Subaru knows it.

 

There is an emergency manual key in your fob - make sure you know how to use it because it takes more effort than you think it should and the time to find out isn't during an emergency.

There's also a transmission lockout release under the rubber cover in the cubby so that in case of a power failure you can still put the transmission in neutral so it can be pushed.

Edit: P.S. The manual emergency key does work except in the case of a guy who had a used Outback that came with a BLANK emergency key. Test yours.

 

Thanks for the clarification. The emergency key seems very fragile, and I will test it. Did not know about the emergency transfer release under the cubby box. Wondered how I would get it on a flat bed from my drive if dead battery. If the key doesn't work by some chance, does Subaru, or locksmiths have an alternate solution?

 

Hi Folks - just closing the circle on this thread. I checked the two ground connections coming of the the negative pole and the neg pole itself - gave everything a wipe with sandpaper and reconnected. The fault appeared to be in the positive pole - some buildup of whatever electrolytic crud accumulates around battery poles, but more significantly, the clamp wasn't clamping well, regardless of how tight the clamp screw was. The red plastic shroud for the positive pole has a small "ring" attachment that inserts between the jaws of the clamp and through which the clamp screw passes - no obvious function for this ring except to keep the shroud in place, but the shroud's not going anywhere in any case. What the ring did do was prevent the clamp from tightening fully. I cut this bit of plastic away, allowing the clamp to tighten better. Good clean and solid connections to the battery poles now. Car started up fine. Thanks for your input.