Hi, I own an 850 wagon, but my friend 2 doors down owns and S70 sedan,
He is having his battery die on a regular/not daily basis...this has gone on for months, he thinks its the alternator,,I think there is a low voltage short/ground that is killing it...is there a common problem with this problem with this model...are there certain or probable things to check...He did have it wired for a trailer but that was long ago and he trailers a lot of stuff with it...he can jump it right off with his jumper battery (everyone needs one of these, I use mine for radio control stuff all the time) and it works fine...the only strange part is he says if he turns on the recirculated air it usually kills the battery that night....doesnt make sense to me, but I am asking for him....thanks...Rog

 

Has he had the battery tested? It could be bad. If so, it could die very easy. How often is the car driven? If not driven that much, a dome light or something could drain it.

Some things get power with the key totally off, the fan should not be one of them. Have him try to operate things with the car off to see if some things are still getting power. Maybe the ignition has gone bad.

 

Take the battery to Autozone they will test it for free

 

You know,,the day after I posted this MY battery died no reason,,lots a little hoods around here will break into a car...I cant tell you how many times they killed my Miata battery...but no open doors this time..just turned the motor over twice and gone...it took a charge, I drove it 5 miles, but still took my scooter to work...Rog