Subaru Outback Forums banner

1 - 7 of 7 Posts

·
Registered
17 OB 3.6R Touring
Joined
·
23 Posts
Discussion Starter #1
My went on a vacation for two weeks and came back with a depleted battery in my 2017 Outback. My dashcam was supposed to detect the low voltage and shut itself. Obviously it didn't. I tried to use battery chargers to charge the battery. Both chargers support 6v and 12v. One is more advanced and one is simpler. The simpler one stuck between standby mode and 6v mode, it would not change to 12v mode. The more advanced one stuck on standby mode and would switch to any charging mode at all. I tried the charger on my other car and worked just fine.

I then attached a jump start battery to my Outback, enabled high voltage mode and the car started. Does anyone know why the chargers don't work on my Outback?
 

·
Registered
'14 Subi OBW, '18 Subi Forester
Joined
·
1,762 Posts
Did you happen to check the battery voltage when it was in the discharged state? Sometimes when they get ultra low, like down to 2.0 V, the chargers just don't recognize them as a battery anymore, and won't kick into gear. How was the battery after you got the car running? Did it come back to life? Is it holding 12.6v after being recharged?
 

·
Registered
2013 BRZ 2005 OBXT
Joined
·
231 Posts
This is why I hate these new "smart" chargers. That and they constantly undercharge batteries. Get an "old school" charger where you set the settings and it constantly charges and it should fix your problem.
 

·
Registered
03 H6 OBW & 06 WRX Sportwagon
Joined
·
17,624 Posts
they have such odd behavior - sometimes it matters if the battery is connected, THEN you plug the charger in the wall, or the other way around.
 

·
Registered
2018 Outback 2.5i Limited Eyesight - Remote Start - Auto Dimming In/Outside Mirrors
Joined
·
245 Posts
I have heard with some modern chargers if the battery voltage is too low, the charger could interpret the low voltage as a bad cell (or some other type of error) and then refuse to charge.

A trick I have heard folks doing is that they have available (lucky them) a second good battery (from something else maybe). They then hook the good battery in parallel to the bad. Now hook up the charger. The good battery will trick the charger into thinking all is okay, or at least good enough to charge. Your charger will in effect be charging both batteries however in time the bad battery will be brought to a point where the good battery can then be taken out and then just charge the bad one.

You might be able to resurrect your bad battery this way.

Hope this makes sense.

Edit:

Assuming good and bad are connected parallel (positive to positive and negative to negative) I would hook the positive of the charger to positive of one battery and the negative of the charger to the negative of the other battery.
 

·
Registered
17 OB 3.6R Touring
Joined
·
23 Posts
Discussion Starter #6
I tried different connecting sequence - battery first and then plug in or plug in and then connect the battery, etc. It didn't matter. But the manual did ask for a specific sequence depending on how the battery is grounded.

After jumpstarting my car I went on a ride to let it self-charge. The battery charger worked afterward. Looks like this confirms theories from you guys that smart chargers may not work on batteries with very low voltage. When I first measured the voltage of the battery, it was very low, around 2v, I think.

The charger worked fine and showed my battery 100% charged this morning. I have not had time to check the voltage. Hopefully, it still has good voltage when I get home this evening.

Conclusion:
Modern smart battery chargers may not work when the battery is in very low voltage. Either jumpstart the car, go on a ride to charge a bit and then use battery charger, or parallel link a good battery to the car to trick the smart charger.
Alternatively, get an old school battery charger :)
 

·
Registered
03 H6 OBW & 06 WRX Sportwagon
Joined
·
17,624 Posts
you can expect any typical ca rbattery that has experienced complete discharge to lose a little of its lifespan, but, good that you're gonna get some service out of it.
 
1 - 7 of 7 Posts
Top