Hi all- 2016 Prius owner. I’m not super car proficient so excuse my ignorance. At the beginning of Quarantine my car died (I hadn’t driven it for 3 weeks) and I had it jumped. Message was about 12V battery. Guy suggested my battery was weak and told me to be sure I was driving it a few times a week. After a couple months l, I went away for about 10 days. When I got back—car was dead again. This time I had the battery replaced. I’ve been driving it consistently—albeit sometimes for very short distances—for months. On Sunday, after not having driven it for about 6 days, I went out and it is dead again! Is this normal or should I go get this looked at? I bought a NOCO Boost Plus to try to get it started (though I’m afraid the cables aren’t long enough to reach the battery and ground where manual suggests to ground—any thoughts there?) But want to know if I should be driving this straight to my garage once I get it up and running! K
Check none of the interior lights or the boot light is on, I turned my boot light off at the switch because it's not always easy to see if it's on when the hatch is closed. If you have a dash cam make sure it's fed by an ign live feed, not permanent live. I often leave mine unused for a week or two without problems. If all else fails, you could disconnect the battery negative terminal as a temporary solution, IIRC you only have to reset the auto windows when reconnecting.
Given what you have said, it probably is in the range of "normal" because....... New batteries often are not fully charged when installed. The onboard charging system is designed to keep a fully charged battery full; it takes it a LONG time to recharge one that is low. "Very short distances" might discharge it more than it will recharge during the trip. You NEED to be able to connect a small battery tender charger to it, NOW for several days to be sure it is charged up and to connect when it will just sit unused. A cheap "trickle charger" does not qualify. If you can't do that, then have a shop charge the battery fully and then arrange to drive it about 30 miles (an hour) once a week all in one trip. This situation is not unique to hybrids but their smaller 12 V batteries seem to be a problem more often.
Are you in a hot area of California or a moderate area? If it's hot, your 12V may be getting a little long in the tooth and not holding a charge like it used to. Still, my 2017 Prime recently sat undriven for three weeks. It was down to 12.4V iirc. It started fine. So you might have something draining it as @kithmo kindly suggests. It might be most simple to have the battery tested before trying to chase down a phantom load unless you recently added something that could be suspicious.
Read up a bit on batteries, and get an appropriate smart charger. CTEK 4.3 is what I'm using; the car's hooked any day it's not being driven, and left connected till next use. Beats driving around just to charge the battery. Hopefully a charger is practical for your scenario, you have secure outlet and power outlet. If not consider a kill switch to stop the phantom loads, and/or an internal charger you just need to run a power cord to. NOCO Genius GENM1 is one good option.
