I learned over the pandemic that a Toyota Camry Hybrid would eat its 12V AGM battery very easily. In this case, it is a deep-cycle AGM and isn't even used to start the ICE. It's "just" to run accessories and boot up the power control system that engages the much larger hybrid battery.
One such Camry in our extended family was parked for a few months and the battery failed. We got an expensive OEM replacement and tried to make sure we drove the car every week or two. It failed again in just under three years. Meanwhile, we have an entry-level Audi that also often gets only a short local trip every week or two. It is still on its original AGM battery after 6 years, and this one has to actually start the ICE.
So, I am disappointed to find that Toyota engineers could not be bothered to apply whatever basic power management logic the Audi folks did to protect the battery. Worse, the Camry has this big NiMH traction battery, and I would have imagined some clever backup strategy to infrequently top-up the 12V battery if parked too long, so it would be reliable.
In the end, I gave up and installed an old-school battery cut-out switch, so we can just disconnect the 12V battery if not planning to use the Camry for more than a few days. Every time I operate it, I'm giving the Toyota engineers a rude hand gesture in my mind.
Smart electric drives prior to 2016 used their “[not] clever backup strategy” to cyclically try to keep a failing 12V battery charged and that could result in flattening the traction battery and eventually bricking it.
Ha, that does sound somewhat un-smart. Of course, when I imagined clever, it would include enough state and timer-based behaviors to recognize a bad trend and protect the traction battery too.
It should be feasible to monitor voltage levels and rates of change and signal an error condition rather than silently destroy itself...
One such Camry in our extended family was parked for a few months and the battery failed. We got an expensive OEM replacement and tried to make sure we drove the car every week or two. It failed again in just under three years. Meanwhile, we have an entry-level Audi that also often gets only a short local trip every week or two. It is still on its original AGM battery after 6 years, and this one has to actually start the ICE.
So, I am disappointed to find that Toyota engineers could not be bothered to apply whatever basic power management logic the Audi folks did to protect the battery. Worse, the Camry has this big NiMH traction battery, and I would have imagined some clever backup strategy to infrequently top-up the 12V battery if parked too long, so it would be reliable.
In the end, I gave up and installed an old-school battery cut-out switch, so we can just disconnect the 12V battery if not planning to use the Camry for more than a few days. Every time I operate it, I'm giving the Toyota engineers a rude hand gesture in my mind.