Car didn't start after sitting with a/c and radio on

[soobiedoobie]

Now in my case it's a 2016 Subaru Legacy.


Yesterday I drove a relative to the DMV and while sitting waiting about 30 minutes, I had the car turned off with the key in the 'on' position so I could get a/c going as I listened to the radio.



And as the radio and a/c kept running when it was time to go, the car wouldn't start.



So I turned off the radio and a/c and tried again. And again. And again. Each time, I got fewer electronic signs of life as if the last bit of power was draining from the vehicle. I figured the battery was shot or something.



I bought the car Certified Pre-Owned a year ago this month. It has an OEM Subaru battery dated 3/20 and I've only put 6k miles on it. I called for a jump. While waiting for him, I decided to try the car again after sitting about 10 minutes. It began showing more electronic signs of life (the chimes and more dash electronics came on) and I even heard the engine try to turn when it didn't before and it was just dead quiet. I didn't try starting again after that.



So after I got a jump (thankfully free courtesy of the CPO roadside assistance package from Subaru), I went straight to a Subaru dealership and had it inspected. I pulled in, turned the car off and told them what happened. The service agent gets in and immediately starts the car without issue. They test the battery and electric system and do the all-around inspection of the car that Subaru dealerships offer (all free thank goodness), and tell me the battery is showing 100% charge and all electronics are fine. They didn't want to change the battery because although it is covered on warranty, I didn't have the original paperwork from the Subaru dealership that installed it so I took it home and it's been fine since, though I haven't sat with electronics and a/c on with the key turned in the 'on' position.



The guy who jumped my car says he encounters a lot of Subarus with battery draining issues relating to something about the car's onboard computer not directing the battery to recharge properly. He said some people go through a battery a year. Being a complete layman about such things, I was wondering if anyone else had heard of something like this.


The car is fine but apparently I cannot sit with the engine turned off and radio and a/c running for any length of time.



Until I can get more a grip on this, I'm going to buy a portable jump starter and battery charger. It seems to me like there has to be a flaw in the car to where it has difficulty running electronics with the engine off and retaining enough power to turn the ignition as if it's not recharging appropriately.



I've never seen something like this in my life.

[Stealthee]

This is simple. You killed the battery by sitting with things on and the car not running. The alternator needs to turn to recharge the battery. The alternator can only turn if the engine is running. Also your A/C wasn't doing anything. You simply had the fan on. The only way your A/C is going to work is, again, if the engine is running.

The reason the car started for the tech was that it is relatively new, and once you got a jump the alternator recharged the battery.

Sitting with the radio and fan on, and the car not running is going to kill any battery. This isn't some crazy Subaru only thing.

[brcidd]

Agree with above--

That's why there is an "accessory" position on most ignition switches, to run only the radio and things that don't draw big amps- like a blower motor.

[soobiedoobie]

Originally Posted by brcidd

Agree with above--

That's why there is an "accessory" position on most ignition switches, to run only the radio and things that don't draw big amps- like a blower motor.

Well it does have an accessory position but I advanced it to on because accessory didn't offer the option of any kind of fan.



So another question I am researching is the OEM battery's reserve capacity. I'm seeing Subaru owners saying the OEM batteries are garbage in that sense and also in terms of cold cranking amps (odd for cars marketed as snow beasts) that have a CCA rating under 400. I'm having a hard time finding the specs on mine, Subaru parts websites don't say and I can't see what it is when I pop the hood.



I'm thinking I need an upgrade, especially with the multiple complaints I'm finding about lackluster power ratings of Subaru OEM batteries.


I have noticed the installed OEM battery looked small and is about 1/5th smaller than the size of the battery tray.

[ctesla]

hey soobie, welcome to Automotive Forums..
Stealthee is correct. without the engine turning the A/C compressor,
the clutch was not spinning; or compressing anything, so just the blower
was moving what was left of the cool air through the ducts, but not 'making'
anymore.. so the blower motor was using alot of amps, as well as the infotainment
console, and possibly your lights were on (as many of your newer vehicles immediately switch either daytime running lamps, or full headlights on) with the key to ON; as opposed to ACCessory..
the minimum ColdCrankingAmps for your subie should be about 450-540..
Cranking Amps is what the battery has to start the car at freezing: 32deg/0 celsius.
CCA is measured at 0degrees/-17.8C
here in colorado you would do better with a 650/700+ in CCA.
you mention the reserve capacity.. this is a minutes amount that the battery can function w/o dying; while running some accessories, to get you home, or to a service station..
a 400cca will be fine for the rest of the summer, but before we get into oct., plan on upgrading.. Subaru tech, may have put a smaller battery into your battery box..
your "Group Size" of battery for your Legacy is a #26; and their are many aftermarket batteries with a superior amount of CCA and reserve cap.; since the 400 probably was a 50-65min. reserve, and an 600 CCA battery will produce volts and amps for 80-90min.
hope this helps..

[soobiedoobie]

Much appreciated. So am I even OK running on this battery for now until I decide what to replace it with? I used it today for some shopping and it ran normally. I work a 16 hour shift tomorrow and I assume it won't conk on me. I ordered a portable battery charger/jumper but that won't come until about Thursday.



Also... should I go for an old fashioned acid cell battery or an AGM? It seems that old school is better for Colorado weather.

[Stealthee]

AGMs are better for cold weather.

[ctesla]

soobie,
Stealthee is right again.
while old school batteries are ok (and affordable) as most all people still use them,
AGMs and Gel cells are superior for hot and especially cold weather..
Absorbed Glass Mat batteries cost more; however, they also can last potentially 1-3 yrs
longer in a vehicle (3-5 yrs in a solar home), so this outweighs cost hike..
also, they have the woven mat material inside; as opposed to a lead plate, so
temperatures do not affect them, they do not leak the sulpheric acid if cracked, and
they do not vent harmful chemical vapors; which is why racers love them, as they can mount in trunk, farther away from engine, yet will hold a 100% charge after six plus months with no sulfation, and a higher amp/hour (and usually reserve capacity) ratings, at extreme high or low temps; and 15 times more resistant to vibration (colorado roads anyone)..
i have been using Gates Optima batteries off south broadway since '91; until the rubber company closed their doors, and then i will buy optima or interstate (whichever amazon has on sale); and then rotate my car battery into a solar/wind project (as i've had some optimas last for 15yrs)..
they are definitely worth the money; if you can afford..
and just FYI, autozone (and sometimes others) have a policy:
WITTDTJR (wit-uh-jer)
what it takes to do the job right; and will offer free battery changes, with purchase..
walmart i think is about $7-10..
hope this helps..

[soobiedoobie]

I appreciate you guys! AGM it is.

[soobiedoobie]

The Subaru OEM is 550 CCA btw.

I'm eyeballing this 850 CCA Odyssey AGM with a 4 year warranty.

[ctesla]

if you are shopping locally, o'reilly usually carries optima.
part# red25
about $200.
725 CCA, almost 1000 CA, with a 90min. reserve..
amazon, same pt#, same price, delivered to door; and no core charge..

[soobiedoobie]

I'm quite amazed the car's manual doesn't say what size batteries will fit. I see some saying on web forums that the Outback will take a size 34. The Legacy has the same engine.

[ctesla]

yes, but the legacy has a lower slung hood..
while the group 34 might fit, it is slightly taller than the 25..
you do NOT want to close the hood and build an arc welder..
go to walmart, or auto store, and measure, as those top posts
do sit a little higher..
25- LxWxH - 9 1/16 6 7/8 7 7/8
34- LxWxH - 10 1/4 6 13/16 8 7/8

it should work; just double check prior to purchase; or install..

[soobiedoobie]

Originally Posted by ctesla

yes, but the legacy has a lower slung hood..
while the group 34 might fit, it is slightly taller than the 25..
you do NOT want to close the hood and build an arc welder..
go to walmart, or auto store, and measure, as those top posts
do sit a little higher..
25- LxWxH - 9 1/16 6 7/8 7 7/8
34- LxWxH - 10 1/4 6 13/16 8 7/8

it should work; just double check prior to purchase; or install..

I've seen that someone installed a 34N into a 2016 Outback which is the Legacy's raised wagon twin.

[ctesla]

yes, the 34 group battery costs the same, and will have a larger CA/CCA/reserve..
if it will fit; you're gold..
subaru probably installed the same battery tray in vehicles, to keep parts cost down; and
generic means, they are always available, and swappable..
the larger base of the tray is probably for the group 34; and will probably fit;
just make sure of the hood clearance.. a larger, more powerful battery will not do
anything to your vehicle and system; except power it more effectively..
i just haven't worked on a '16 leg; so i cannot tell you what betteries will fit...
.. i did own a '93 subie AWD for many years, and a group 24 (ford) battery squeezed
in to the cavity pretty nice; w/o even needing J-hooks and tie-down bracket..
but then i switched to a Braille Racing battery, that was the size of cigar box, and weighed only 14lbs., and still had over 1000 pulse cranking amps; BUT--
my 93 had WAY less in computized controlled electronics than yours; so stick to
what subaru recommends..