I put in a new battery around May this year. Although I got a cheaper one, the battery specs seemed sufficient for the car. I've been driving it every month or so, and the battery often dies and needs jumping. After driving it, it starts once or twice, but then dies again a few days later.
- Car is a 2006 Volvo XC90 which I drive about once a month
- The previous battery would also die often, although it was about 5 years old at that point
- The current battery is a SuperStart 48ECO with 615 CCA (manual recommends 600): https://www.oreillyauto.com/detail/c/economy/more-powersport/batteries/battery---best-fit/7272aa5cfedd/super-start-economy-battery-group-size-48-h6/ssbk/48eco
Most recently, I drove it to my garage to do some maintenance. It seemed to start fine on its own, but the next day the battery was dead showing only 10.3V. While doing the maintenance I turned on headlights for about 3 min, but nothing else and didn't start engine.
I bought a supercapacitor jumper which is supposed to use the low voltage in the battery to jump it, but it failed to do so on mine. I then charged the jumper from the plug and jumped the car that way, drove it around for ~30 min, then parked.
On the same occasion I also checked the charging current (14.3V) and fuses (all showed no voltage with car off).
About a week later the battery is once again dead, with 3V. The temperature did drop from about 60F to 30F during this week, although my other car had no issues.
What should I do here?
- Is the battery just bad and I should replace it (with the same model)?
- Is the battery model too weak and I need to buy a better battery?
- Is the fuse method insufficient and I need to look harder for a leak?
- Is this expected behavior because I drive the car too rarely? Other cars seem to start even after 3 months of not being driven
I initially thought that my car is leaking current when off, but since the fuses showed nothing I assumed that's not the case. I haven't tried putting an ammeter in series with the battery. My next thought is perhaps something is wrong with the battery, and it's only holding a superficial current. But it's suspicious that the old battery was also dying.