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Battery Discharged while parked

23K views 47 replies 13 participants last post by  DavSmile  
#1 ·
My parents recently purchased a 2020 Crosstrek Limited that was a CPO car with an extended warranty. They don't drive many miles, and most of the mileage is 2-3 mile short trips. Recently, they went 4 or 5 days without driving the car, and when they went to use it the battery was dead.

The Subaru dealer came, charged the battery, and said that nothing was wrong with the car. Then he told them something that seems strange to me. He said that there was some motor (?) involved, and they needed to start the car up every day to prevent the battery from going dead. Unfortunately, they aren't very knowledgeable, and didn't ask any further questions or for a more clear explanation of what the problem was.

I know that there are systems in most cars now that will slowly drain the battery when the car is parked, but the need to start the car up daily is clearly excessive, and would indicate to me that there is something wrong. The battery in a 2020 car should still be in good condition.

Has anyone else experienced similar problems? Should I insist on a more comprehensive diagnostic from the dealer?
 
#2 ·
My parents recently purchased a 2020 Crosstrek Limited that was a CPO car with an extended warranty. They don't drive many miles, and most of the mileage is 2-3 mile short trips. Recently, they went 4 or 5 days without driving the car, and when they went to use it the battery was dead.

The Subaru dealer came, charged the battery, and said that nothing was wrong with the car. Then he told them something that seems strange to me. He said that there was some motor (?) involved, and they needed to start the car up every day to prevent the battery from going dead. Unfortunately, they aren't very knowledgeable, and didn't ask any further questions or for a more clear explanation of what the problem was.

I know that there are systems in most cars now that will slowly drain the battery when the car is parked, but the need to start the car up daily is clearly excessive, and would indicate to me that there is something wrong. The battery in a 2020 car should still be in good condition.

Has anyone else experienced similar problems? Should I insist on a more comprehensive diagnostic from the dealer?
There have been lots of posts here about this already, especially with the pandemic lockdowns. I'm guessing that the motor he's referring to is the fuel evap system that comes on after the car has been stopped for a few hours. Otherwise the parasitic drain is negligible. Personally, I think the OEM battery is crap and replaced it after only a year with an Odyssey Extreme AGM and haven't had a problem since.
 
#3 ·
It takes 10-20 or so minute (I'm sure the keyboard commanders will correct me) to recharge the battery loss from a start. If they are starting the car and driving for only several minutes at a time, the battery will slowly drain.

AstroKats nailed it - the OEM battery is underpowered poo to begin with. On top of that, when the battery is flattened, even once, it maybe sub-optimal for the rest of its life. A Solar Car Battery Trickle Charger may be a good investment to keep it topped up. OR once a week they should go for a longer drive to give it a healthy charge.
 
#5 ·
Bensandford, welcome aboard!

Yes, this is a well known problem. Not just with Subaru, but with many manufacturers. There are a couple of factors. First, the OEM battery is indeed weak. Second, cars nowadays have many systems which may bleed off power even when the car is turned off. Doubly true if they've added a dash-cam system or alarm system which may drain a significant amount of power all the time. Third, the charging systems are designed to save energy by not fully charging the battery. Thus fuel economy might be ever so slightly improved, but the battery is never fully topped off either.

So, if they don't drive often and they don't drive very far, the battery indeed will be somewhat discharged all the time. They probably use more battery power starting it than can be replenished in a 2 mile drive.

In my 2018, I have found the charging system only works at full voltage when an accessory is turned on such as the fan blower. Now this is a huge change from the good ol' days, when it helped to turn stuff off if you wanted to ensure a fully charged battery.

For your parents, I would recommend they always leave the fan blower on at least the lowest on setting rather than off. In my 2018 this forces the charging system to operate at full voltage.

Disable the Start/Stop function. This is where the engine turns off every time they come to a full stop, and then restarts when they go again. Manual transmissions don't have this function, but if they have the automatic transmission I believe it does.

If they can, drive for about a half hour once per week.

And/or install a battery charger/maintainer. There are a lot of options. Basically, hard wire to the battery so they can plug it in at least once per week. A maintainer will keep the battery healthy and charged. A plain old fashioned charger will damage the battery if left attached, so they should use a modern maintainer. NOCO Genius is a good brand.
 
#6 ·
The Subaru dealer came, charged the battery, and said that nothing was wrong with the car. Then he told them something that seems strange to me. He said that there was some motor (?) involved, and they needed to start the car up every day to prevent the battery from going dead.
That is ridiculous. If one is going to be out of town for a few days, one has to either arrange for somebody to come over every day and run the car, or put the car on a trickle charger? Really?
 
#7 ·
No, I've been monitoring the battery for a while now and the parasitic drain is negligible. I calculated in one of the other myriad battery threads here that a healthy, well-charged battery (say, 80%) should go a couple of months without the car being driven. We've gone a couple of weeks and not had a problem (albeit with the Odyssey Extreme). It's the short journeys and the battery being left at a low level of charge that will kill it.
 
#8 · (Edited)
I have had my Crosstrek now 3.5 years, and my OEM battery is still good. It doesn't get driven much (my EV is our primary car now) so I do keep an eye on it (with the BM2), to make sure it never gets too low. So far, so good, and have not even had to top it up.

What kills OEM batteries is a big discharge, and then relying on the car to fully recharge it instead of an external charger. They won't last long after that. That's where the Odyssey is superior, as not only is it a better battery all around, but it can better withstand a full discharge. It also accepts a charge faster. A bad OEM battery does not accept a charge very readily, which is why it needs to be charged offline.

I use Odyssey batteries in my airplane, where there is a high chance of forgetting to shut off the master sometimes. Despite a panel light I still keep doing it. Has happened to my current Odyssey a few times since I bought it 10 years ago. One time it was dead (and I mean totally dead) for 3 weeks, when I went to go for a flight. Charged it up, and it was good again. No regular OEM battery could take that, without serious loss of power and capacity.
 
#12 ·
No, no, no ... needing to start the car every day is NOT normal, period. Regardless of whether you still have the OEM battery or not.

Even after the OEM battery in my 2013 was a couple of years old, there were several times when I left the car for a couple weeks and the thing started right up when I returned. If I remember right, the longest period was 24 days.

Get the battery fully charged, either with a long drive or an external charger, and the situation should not recur, even if your driving is mostly short trips. If the battery's only a year or so old and it happens again, I'd really suspect there's something that's causing a parasitic drain.
 
#19 ·
Yeah, but in a good way. It can accept a faster charge, and has a higher full charge voltage. It doesn't affect the car's ability to charge it.The Odyssey also has a denser energy pack, ie more power (CCA), and more reserve capacity, for its weight.
 
#22 ·
Actually, I gave up on powering the dash cam from the car's battery a long time ago and got a dedicated parking mode battery instead. The reason I went looking for a better battery (and followed your recommendation) was after driving several hours up into the mountains and finding that it would barely start the next morning when it was below freezing. Overkill depends on your perspective. It cost probably $150 more than the OEM replacement but I expect it to last at least twice as long maybe more and is better suited to how OAK drives it (mostly short commutes in traffic), and that was before the pandemic...
 
#26 ·
I think the reason for the hard starting was that the OEM battery was already damaged from your past dash cam discharges, and no longer had sufficient power or capacity when you went up into the cold. I have had mine up in the cold skiing many times in the winter (incl over night), and always had good power when came time to start it. But I have never overly discharged it. I expect it to last at least 5 years (just 1.5 to go).

In my boat, (with a V8 motor), I have just a regular car battery that is now about 7 years old, and it is still good. It is used infrequently, but I have a small 15W solar panel in the windshield plugged into the cig lighter (which is always live to the battery), and that keeps it topped up while moored at my cabin in the summer. In the winter, when I store it in my hangar, I also top it up after about 3 months or so. We took the boat out to the lake just a couple weeks ago, and the engine fired right up, no shortage of battery power.

So if you take care of a cheap OEM or car battery, they can still last a long time. But any abuse can kill them quickly.

Reminds me when I am at the dealer, and see cars in the show room with the rear hatch/gate open. Probably a lot of batteries get damaged before they ever make it into customers' hands. And a few years ago, when I was interested in the Ascent, I took one for a test ride. But they first had to jump start it, as the battery was dead. And this is a brand new car.
 
#30 ·
FWIW, this thread reminded me that it has been a while since I topped up the Odyssey, so I put it on charge last night (Noco Genius 5A). It's an interesting chart - you can see the dip when I disconnected the charger at 6am then another dip at 10am when I approached the car. Note, I hadn't even opened car at that point, that's when it woke up:

305482
 
#36 ·
It has been a struggle to keep both of our cars' batteries charged during the pandemic. Our older car is a Hyundai Elantra and I now need to replace its battery. It gets driven less than the Crosstrek and even though I have been periodically charging the battery overnight, the battery will no longer hold a charge. The battery is about three years old.

When I was looking at the specs for a new battery I was surprised to see that it's a much more powerful battery than the OEM in the Crosstrek! This is a smaller, lighter car, FWD, no stop/start, and nowhere near the electronics in the Crosstrek (just a basic radio and that's about all). Yet the OEM battery is a Group 47 650 CCA, whereas the OEM Crosstrek battery is a Group 35 470 CCA.

Interesting, and confirms what I have suspected about the OEM Crosstrek battery...
 
#37 ·
My parents recently purchased a 2020 Crosstrek Limited that was a CPO car with an extended warranty. They don't drive many miles, and most of the mileage is 2-3 mile short trips. Recently, they went 4 or 5 days without driving the car, and when they went to use it the battery was dead.

The Subaru dealer came, charged the battery, and said that nothing was wrong with the car. Then he told them something that seems strange to me. He said that there was some motor (?) involved, and they needed to start the car up every day to prevent the battery from going dead. Unfortunately, they aren't very knowledgeable, and didn't ask any further questions or for a more clear explanation of what the problem was.

I know that there are systems in most cars now that will slowly drain the battery when the car is parked, but the need to start the car up daily is clearly excessive, and would indicate to me that there is something wrong. The battery in a 2020 car should still be in good condition.

Has anyone else experienced similar problems? Should I insist on a more comprehensive diagnostic from the dealer?
Subaru batteries are garbage. I bought a replacement battery from dealership and always had a battery drain. I brought back twice and was told my new battery passed all protocol testing. I left there & bought a odyssey red-top AGM battery and had them install it. I had No problems, since. I feel like I was stiffed $190 plus $35 reconnect fee. I regret giving them the battery for disposal, they are probably gonna sell it to the next elderly customer & play the same pass protocol game.
 
#39 ·
My original battery was great, but the replacement was not. The replacement was definitely not the same as what originally came in my car. I will never by another replacement battery thru a dealership again.
I just wish someone would own up to the quality flaw passed to their customers. Sweeping under the rug does no good for return business.
 
#48 ·
Subaru just announced (2/29/2024) that "As part of the Subaru of America's dedication to customers satisfaction, Subaru of America, Inc. (SOA) is announcing a Warranty Extension of the DCM on certain 2016-2018MY Legacy, Outback, Impresza, Crosstrek and Forester vehicles and 2017-2018MY vehicles.

Affected vehicles are equipped with a DCM and may experience a dead battery as a result the DCM continually trying to access the 3G network which is no longer available and have not received a previous DCM update. This will extend coverage on vehicles sold or leased in the United States.

The notice goes on, but I will give you the key information. Ask the dealer if they can print the notice for you if you having received one.

If you have any questions about this notice, please contact the DCM Warranty Extension Hotline at: 877-551-7149.

I believe the lawsuit brought about a solution.