I have a 2017 Toyota Yaris Hatchback. The car had some cranking issues. I did a cranking voltage drop test (dropping to min 7v when cracking), it seemed like the battery was done. I replaced the battery with a SuperStart battery from O'Reilly. Car was working fine and the issue seemed to be fixed.
Shortly after, I went to travel for 3 months but forgot to unplug the battery. After I came back, the car was cranking fine for 3 weeks but the (new) battery eventually started losing more and more charge. Now, the battery goes from full to half in a night.
- Checked and cleaned battery terminals
- I did a test for parasitic draw, but didn't see a lot of draw (just about 15mA).
- Alternator puts out about 13.3v-13.7v in idle, 13.8v at about 2000rpm. Is that too little? I keep reading conflicting information online (some say not less than 14v, some say not less than 13v, ...)
- When I drive around for a little bit, the battery charges up to 12.6v. It does crank fine after, so I assume the starter is ok. But if the car sits for the night, the battery drains down to at least half and the engine cranks slowly.
- At this point, I'm 99% sure it is the battery, but since the battery is new I'm still a bit skeptical that the car sitting around for 3 months would destroy the battery (I had other cars sitting around for longer without issues).
- If you think so as well, what else could I check? I'm really trying to avoid buying another battery.
- If it is the battery, which battery brand can you recommend?