Accessory mode kills the battery?

My car is 2 years old with 17k miles on it. So I was sitting in my car in accessory mode while setting up my car play with my new phone. Next thing I noticed was an electronic brake error, so I turned off the car and then it wouldn’t start. We then were able to jump start the car. The car was in accessory mode for maybe 15 mins. I’m surprised it killed the battery.
Would it be worthwhile to take it to the dealership tomorrow? Are batteries covered under the 3 yr/36k warranty?

Yes, the battery should be covered. I was actually warned by two different people at the dealership not to have the car in accessory mode for long because the battery in the car is small and will drain quickly with all the electronics in the car. Guess they were right. Get it checked though, just to be sure. Any parts store will have a battery tester, as will the dealer. Good luck!

Thank you! Hopefully the dealership can check it out quickly.
So is the electronic brake error related to the battery dying? I was researching that and it seems like it’s another issue altogether.

Civic Fan 2016 said:

Thank you! Hopefully the dealership can check it out quickly.
So is the electronic brake error related to the battery dying? I was researching that and it seems like it’s another issue altogether.

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An interesting answer would be to the question:-

How much current is drawn with Accessory on, ( with and without the radio running at a reasonable volume.) ?
Lights, Seat Heaters, Fan etc all OFF.

Since I have a Clamp On Amp Meter, I'll try to get a reading later today (on a 2018 Si), and post it here this evening.

Dropped it off at the dealership for testing. The service advisor said that this is not uncommon. We'll see.

I have heard that the batteries in the US model Civics are pretty weak and a lot have failed under warranty. It should be covered.

Why are the batteries so piss poor in these cars? My last two cars were an Elantra and a Forte. Not exactly luxury cars but the batteries lasted 7 years plus. It makes no sense for Honda to use crap batteries because of the warranty replacement costs they're shelling out.

wow. i eat lunch in the car regularly when on the job with acc mode on. been 1/2hr or more and not had any problems. guess i win the battery lottery today.

Battery failed the test. They are replacing under the warranty. I live in TX and I know the heat shortens the lifespan of the batteries. In my old honda, I was replacing batteries around the 3 year mark even though they were warranted for 5 years.
Of course they just tried to upsell me on cabin air filters and brake fluid.

caspar21 said:

wow. i eat lunch in the car regularly when on the job with acc mode on. been 1/2hr or more and not had any problems. guess i win the battery lottery today.

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The Canadian Civic batteries are a larger size, at least on the turbo models. Group 47 vs 51r in the US.

caspar21 said:

wow. i eat lunch in the car regularly when on the job with acc mode on. been 1/2hr or more and not had any problems. guess i win the battery lottery today.

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It must literally be a lottery...

What are the odds, I listened to music on accessory mode for 30 mins during my lunch today, didn't start in the afternoon. Done this dozens of times before with no problem. Fan was off, literally only had the radio on. Had a co-worker jump it, but oddly when it fired up it didn't sound like a car with a dead/dying battery typically does.

Guess I'll be using headphones from now on lol.

3-year anniversary present for my car's a new battery it seems.

I've been out of the Honda game for a while. Does Honda generally use crap batteries? I've never seen a new car with this amount of battery problems.

I don’t know if this is coincidence or not, so when I left work, I got the key fob battery low warning. Really?

Got lucky and found the right battery in the house and replaced it.
Ordered some air filters too and will do those later this week. The dealer wanted so much money for that.

marauderguy said:

The Canadian Civic batteries are a larger size, at least on the turbo models. Group 35 vs 51r in the US.

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I'm in Ontario Canada and looking at replacement options for my 2018 Hatchback 1.5 Turbo...all Canadian retailers that I've seen list the 51r for battery size. I hope I have a group 35 but Napa, Optima, Canadian Tire and AGM.ca all say 51r for direct replacement to OEM battery for 2018 turbo civic I will update if different when I can get an actual look under my hood.
Curious tho..why do you say us turbo drivers north of the border have group 35?