> Electrical engineers in 2025 have so many little power drains that any car left undriven for a few months has a dead battery.

Interestingly enough, the quiescent current drain of my 2020s era vehicle is lower than either of my past 2000s era vehicles when I measured it.

The phenomenon of batteries being drained after a few months of being left unattended is not new.

The big issue tends to be complex logic for going to sleep often getting stuck. Ie. "oh, I was trying to use the LTE connection to poll for updates, but the connection got reset so I kept the CPU awake forever whilst retrying every 5 minutes rather than going to sleep mode".

Older cars had this too - I had a bunch of cars which would kill their own batteries if not locked - the engineers assumed that all owners lock the car when walking away, which often isn't the case in your own garage.

It's not, but older cars tried to keep their batteries fully charged. Newer cars with the so-called "smart" alternators never keep the battery full, they always leave some empty capacity to recover energy while moving.

I had this same problem in my 2005-ish Lexus! I got a cheap switch[1] on Amazon and put it in-line with my battery. If I’m going to leave the car undriven for more than a week, I just disconnect the battery with the switch. It’s been great, no complaints so far.

[1] this is the switch I got https://a.co/d/90K0QiH

Doesn't anti-theft precautions kick in when you do this? On my Honda, if the battery goes completely dead or when I replace it, I have to enter a code in after, and IIRC all my radio stations reset, so it would be really inconvenient to do this often.

My way around this, which is also somewhat inconvenient- is that I pop the hood and connect a trickle charger if I have a feeling I won't be driving for a few weeks. I have a garage so this is the lesser evil.

Hmm I do have to put the key in the door when I’m reconnecting the battery, or else the car alarm will go off. That’s the only thing I’ve noticed though — maybe it’s just too old to have more complex features? I never listen to radio, so the stations may be reset and I just don’t notice.

My accord is a 2007 so not much newer than yours. We can Uber around for most trips but find it very convenient to have a car at times. If it works for you great, I thought that was a fairly common thing- particularly in cars of that era, because radio theft used to be so common.

I use a PV trickle charger, the panel is barely 1 square foot or so. Would be nice if it was integrated instead of having to connect/disconnect it constantly. Although, and I'm just guessing, many vehicles that are so seldomly driven are being kept indoors/garaged? (Mine is)

I haven't found any appreciable drain on my EV's primary battery over the longest period I've left it sitting so far (a little over a week, so not that long, admittedly), but the car _does_ do a very bad job of keeping the 12V battery charged and I've already had to replace it once in <2 years of ownership, plus I bought one of those small jump start packs in case it ever dies not at home (luckily, for an EV, it barely requires any power at all to turn everything on and get it started, so the very smallest, cheapest, jump packs are way more than sufficient). A built in trickle charger to combat that would indeed be nice, if the car companies are incapable of figuring out the logic necessary to do it off of the massive primary battery.

EV's are the worst at keeping their 12V batteries charged. Many EV's don't even charge the battery if they're plugged into an AC charger!!!

You can literally leave it plugged in charging for a month and come home to find it dead.