Accessory mode kills the battery?

verbalj

Senior Member
Joined
Jan 1, 2017
Threads
15
Messages
239
Reaction score
103
Location
Long Island, NY
Vehicle(s)
2016 Civic Touring
Vehicle Showcase
1
Country flag
I've gotten used to the time in the battery and I don't know how another battery would affect the car. Also, Honda has some battery replacement warranty system where they can pay for your next battery in full for about 3 years if you buy a genuine battery first.

Screenshot 2020-06-10 at 04.52.00.png
Thanks for the info. I’ll check it out.
 

Dario1101

Senior Member
First Name
Dario
Joined
Jun 6, 2017
Threads
3
Messages
253
Reaction score
90
Location
Miramar, Florida
Vehicle(s)
2021 Honda Civic Hatchback Sport
Country flag
What people are having problems with is the Factory Battery the car came with new.
These are really bad batteries that drain way too fast with light usage, like in Accessory Mode just using the radio.
1.5+ Hours or more just using the Radio in Accessory Mode will drain the Battery too low to start the car.

The Screenshot you provided are just for Honda Batteries bought at dealerships.

Also, these replacements are NOT free. It will still cost you $$ even if it fails in the first month.
"You are responsible for the labor or installation charges."

For $109.99, you can get NAPA battery that has 40 Amp Hours.
https://www.napaonline.com/en/p/NBP6551R?partTypeName=Battery+-+Automotive&keywordInput=si+battery

My Factory Battery was checked by the dealership, & according to their equipment, it is only a 2.1 Amp Hour Battery.

Pep Boys has a Bosch Battery that costs $194.99 & has 45 Amp Hours (see label on the Battery).
https://www.pepboys.com/bosch-platinum-series-agm-battery-group-size-51r/product/844473/2019/HONDA/CIVIC/4-1498 1.5L DOHC

  • Even though I specified my specific car, Pep Boy seems to put "This product may not be compatible with your 2019 HONDA CIVIC" for its Bosch Batteries.
  • The reason this one is a lot more expensive compared to the NAPA one is that it is designed for extreme weather. So, if you don't live in California/Texas or very cold places like Minnesota, the NAPA one will work fine (& a LOT Longer than the Factory Battery).
Hmm... I just got my battery replaced under warranty because I love to run the car just from the battery during driveway moments or to charge my phone or something. I mean yeah the battery could be better but I'm just used to how it operates. That being said, I am definitely open to new batteries like the NAPA battery you mentioned. Is there a place that does battery comparisons or something where I can compare the two batteries?
 

Benster

Senior Member
First Name
Ben
Joined
Mar 20, 2019
Threads
5
Messages
698
Reaction score
401
Location
Nova Scotia, Canada
Vehicle(s)
2019 Civic HB Sport 6MT
Country flag
it's most likely a 45 Ah, no way a car battery only has 2.1 Ah brand new, you wouldn't evne run the radio on that. You need to look at the reserve capacity of the batteries. Similar size batteries will be similar in capacities unfortunately so if you want a better battery you'll have to settle for some weight gain too. Make sure you measure your battery tray and don't buy one bigger than you can secure.
 

Dario1101

Senior Member
First Name
Dario
Joined
Jun 6, 2017
Threads
3
Messages
253
Reaction score
90
Location
Miramar, Florida
Vehicle(s)
2021 Honda Civic Hatchback Sport
Country flag
Reserve Capacity is basically the same as Amp Hours (if the battery does not list Amp Hours, there is a calculation you can use on the Reserve Capacity to get the Amp Hours).

The battery is not new. It's a Factory Battery that came with the car. The car is a little over 1 year old.

According to the dealership's equipment, my car's battery is 2.1 Amp Hours. This is the actual printout from their equipment:
1591918475198.png


Amp Hour:
"An ampere hour (abbreviated Ah, or sometimes amp hour) is the amount of energy charge in a battery that will allow one ampere of current to flow for one hour."​

If you have a 45 Amp Hour Battery, if you run something that uses 1 Amp to run, it will run 45 Hours.

If 5 Amps are used, it will run 9 Hours.

If 10 Amps are used, it will run 4.5 Hours.

If the Factory Radio is on in Accessory Mode & NO other user attached accessory/accesories are attached/running, Honda's Accessory Mode should NOT consume 10 Amps.

If it is, there is a defective component(s) or it is an inexcusably bad design by Honda.

ON mode is a different story. Everything is turned on, including the Engine Management System.
I like to run my car in the ON position often. I note that around 30-40 minutes, with my phone plugged in, the car will then lose the charge on the battery enough to not turn over the engine anymore.
 

Dario1101

Senior Member
First Name
Dario
Joined
Jun 6, 2017
Threads
3
Messages
253
Reaction score
90
Location
Miramar, Florida
Vehicle(s)
2021 Honda Civic Hatchback Sport
Country flag
I updated my response in the last post you quoted.

If the engine is not running, I would recommend using just the Accessory Mode.

There is no need to power other high-power consumption things on the car if they aren't being used.

For the 2020 Civic Si, Honda also lists: "1.5-Amp USB Smartphone/Audio Interface".
I would leave it on accessory mode but it doesn't activate my phone's quick charge capability haha.
 


Prelude2CivicX

Senior Member
First Name
Louie
Joined
Jun 11, 2017
Threads
0
Messages
77
Reaction score
30
Location
Los Angeles, CA
Vehicle(s)
2017 Honda Civic EX-T 6 Speed M/T, 2018 Honda Civic Si, 2018 Honda Accord Sport, 1997 Lexus SC300
Country flag
Im currently having the same issue after about 2 years of owning my 2018 Civic Si sedan. First time the car died on an indoor parking lot after just about 15 minutes of charging my phone and leaving my headlights on by accident due to the "auto" feature. This last time it died I was listening to music while charging my phone. I made sure to turn off my headlights and touch screen to try to save energy but it still died. I called Honda and will be taking it tomorrow for service and a battery test. Lets see what they tell me.
 

the27thaxe

Member
First Name
Benjamin
Joined
Jul 13, 2020
Threads
4
Messages
47
Reaction score
25
Location
Sussex N.J.
Vehicle(s)
2020 Honda Civic Si Coupe
Country flag
So I work at an auto parts store and We typically see Honda's (civics in particular) killing batteries right around that three year mark. Not to try to sell you guys anything, but in the future, it would be worth while to look into an AGM battery. Absorbed Glass Matt Batteries are far more resistant to draw.

The problem we run into is 51R's which in my experience are the more common option (some do use a 35) don't pack a lot of power. 1.5t's don't need a lot of power to crank compared to some other cars and trucks so it makes sense to use a smaller battery to save weight even at the cost of power.

I should have a few more years out of my battery but I'm planning on replacing mine with an AGM when the time comes.
 

M16

Senior Member
Joined
Jun 20, 2020
Threads
2
Messages
50
Reaction score
9
Location
Canada
Vehicle(s)
2016 civic ex
Country flag
I've had the radio on for 2+ hours in acc mode many times in my canadian 16 ex. Always started right up.
 

MuffinMcFluffin

Senior Member
First Name
Brandon
Joined
Jan 15, 2018
Threads
33
Messages
713
Reaction score
306
Location
Elk Grove, CA
Vehicle(s)
1999 Honda Civic EX, 2019 Honda Civic Si
Country flag
How would this battery hold up if watching a 2.5-hour movie at a drive-in theater using the FM frequency?
 


JT Si

Senior Member
Joined
Mar 17, 2019
Threads
19
Messages
1,299
Reaction score
1,151
Location
Place
Vehicle(s)
Car
Country flag
How would this battery hold up if watching a 2.5-hour movie at a drive-in theater using the FM frequency?
Probably fine. I used it to listen to music for an inordinate amount of time while my car was stored in the garage and I worked on the doors and speakers and it still started up no problem.

(OEM Battery being the battery in question)

Eeep, probably not. Also being a standard lead acid battery it won't be happy about that level of discharge.

A standard AGM 51R replacement might be fine for a 2.5 hour radio session if every single accessory is turned off, like the HVAC, lights, etc. At the very least if it was started while it still had enough power to start or jumped it would recover with little to no damage.

But I was definitely talking about the XS Power D5100R, which is a baller battery and would probably have no issue with that kind of session.

Unfortunately the D5100R is so baller I removed it, bought a new uncut OEM battery box, and got the O'Reillys 51R AGM Super Start Platinum. Unless you can fabricate a better mounting box and hold down, the D5100R will shift a lot and rub against the firewall sheet metal, damaging the casing. Since I drive my Si like a racecar this was no bueno for me. If you drive like a normal person it would pose little to no issue.
 
Last edited:

jeeva86

Member
Joined
Apr 30, 2021
Threads
1
Messages
10
Reaction score
0
Location
Ottawa
Vehicle(s)
2008 Acura TL-S 6MT
Country flag
Hi guys,

I just bought a 2017 hbst that finished warranty. Test drive was ok. 3 hours later my car isn’t starting. Both keys were not in the car after the test drive. But while I was standing outside I seen the wiper work so I just assumed it works when I’m near the car with the keys in my pocket. Could I have accidentally put the car in accessory mode after the test drive And thus it killed the battery? I disconnected the battery as I seen the drl on. I am planning on charging the battery and then figuring out how to get out of accessory mode. Am I on the right track or is this the bcm problem? Really like the car and colour combo so it would suck if I have to give it back to the dealer. I might be able to negotiate them covering the bcm replacement as I rather not go the full refund route, although they won’t have any problems doing that.
 

jeeva86

Member
Joined
Apr 30, 2021
Threads
1
Messages
10
Reaction score
0
Location
Ottawa
Vehicle(s)
2008 Acura TL-S 6MT
Country flag
Update: yesterday I measured the voltage on the battery after disconnecting it and it was 10.4. This morning I went to measure it and it’s 24.4! So I reconnected my battery and it’s no longer in accessory mode.

what portion of the warranty does the bcm module come under? I have power train and emission systems warranty remaining. I doubt it falls under that?
 

JT Si

Senior Member
Joined
Mar 17, 2019
Threads
19
Messages
1,299
Reaction score
1,151
Location
Place
Vehicle(s)
Car
Country flag
Update: yesterday I measured the voltage on the battery after disconnecting it and it was 10.4. This morning I went to measure it and it’s 24.4! So I reconnected my battery and it’s no longer in accessory mode.

what portion of the warranty does the bcm module come under? I have power train and emission systems warranty remaining. I doubt it falls under that?
Are you sure you aren't just dealing with the flaky factory battery? The thing is a major common failure point and it can cause all kinds of strange issues due to low voltage from a bad cell or low electrolyte levels.

I sincerely doubt you have a BCM module issue if you haven't appropriately ruled out the battery.

Also, your battery absolutely shouldn't read 24.4V, or even 14.4V for that matter unless the car is on and the alternator is at charging voltage.
 

jeeva86

Member
Joined
Apr 30, 2021
Threads
1
Messages
10
Reaction score
0
Location
Ottawa
Vehicle(s)
2008 Acura TL-S 6MT
Country flag
Are you sure you aren't just dealing with the flaky factory battery? The thing is a major common failure point and it can cause all kinds of strange issues due to low voltage from a bad cell or low electrolyte levels.

I sincerely doubt you have a BCM module issue if you haven't appropriately ruled out the battery.

Also, your battery absolutely shouldn't read 24.4V, or even 14.4V for that matter unless the car is on and the alternator is at charging voltage.
My costco battery in my TL reads ~26V as well when it's just sitting there. During running, it's at the 14.4 mark, I haven't started the civic yet, but I think it might be at 14.4 as well. You're right factory batteries suck, but this BCM item sounds interesting and 2017 may be a culprit of that. Wondering how else I can narrow down whether it's a bad BCM or the battery. I think the BCM symptom displays the accessory mode at different times, it's not always reproducible.

EDIT: Rookie mistake, my multimeter wasn't on the right setting, so ignore all voltage values above this post.

I measured my TL - 12.33V. My civic - 11.3V, I've hooked it up to a charger and waiting for that to complete. Then I'll closely monitor the voltage while started and off. I'll also observe accessory mode after I shut off the car to make sure it's off.
Sponsored

 
Last edited:


 


Top