Extremely doubtful that would drop a good 12v battery to a no start level. Most battery drain issues arise from add-ons like security systems, hitch wiring, after-market radios, dash cams etc.
I rotate my cars out and each sit 6-8 weeks at a time with no issues.
If your really concerned, disconnect the battery or put a battery tender on it.

 

Extremely doubtful that would drop a good 12v battery to a no start level. Most battery drain issues arise from add-ons like security systems, hitch wiring, after-market radios, dash cams etc.
I rotate my cars out and each sit 6-8 weeks at a time with no issues.
If your really concerned, disconnect the battery or put a battery tender on it.

Most car manuals advise you to drive the vehicle at least every 2 weeks to keep the 12V battery charged. The proximity key smart entry must put some extra load on the 12V battery in addition to telematics like Toyota Safety Connect, Remote Connect and Service Connect. So, I thought that may drain the battery even faster.

The battery tender manuals warn you not to leave them unattended due to risk of fire.

 

The 12V batt is probably toast since it has been allowed to live in a prolonged state of discharge.
A 12V batt that always stays fully charged will have a longer service life than one that has experienced discharge events or is allowed to stay in a prolonged state of discharge.

Invest in a smart 12V batt charge w/ the leave behind "pig tails". Hopefully you have a garage to be able to do this. The smart charger will keep the 12V batt fully charged, turn on and off as needed: plug in and forget it. No more dead battery when you need to go.

Noco is one option (Noco Genius5). Unfortunately the "pig tail" Eyelet is an add on accesory (Noco GC00X). Periodically the Nocos go on sale. You can save a few bucks and buy used, esp the accessory.

CTEK is another great option too! The "pig tail" (eyelets are included w/ all CTEKs).
MXS5.0 or Test&Charge models will be pragmatic.

Buy a quality charger and you'll have a useful tool. Be wary of imitation knock offs of CTEK and Noco.

 

Would the smart entry broadcasting 24/7 cause the 12V battery to drain faster on an infrequently used vehicle?

Short answer: no. Modern cars never “sleep” as a number of electronic functions need to remain always “on” (even without add-ons). Disabling smart entry wouldn’t do much as it is only a tiny one of those many systems. Yet, the problem is rather on the other end: keeping battery with a good charge level. Recommendation is at least a couple of 30 minutes trip at 40+ mph each week.

 

vampires

 

If the car is parked for extended periods, a battery tender is in order. a noco genius 2d is perfect for this. no buttons, no modes, just plug it in and it will charge the battery then keep it maintained for as long as it is plugged in. If power isn't available, a 10W solar battery tender on the rear deck, and wire it into some always hot power, maybe just run it straight to the battery.

 

Is there anything else that can be disabled if the car is not driven for a few weeks that will keep you from returning to a dead battery?

If the car is not driven for a few weeks, and you don't plan on putting a batt tender/charger on it, the only way I know to keep the batt from going flat is to disconnect it from the car. That would ensure there is no external drain on the batt. Make sure you fully charge it before disconnecting.

 

My parents' Avalon's battery is completely depleted after about 2 weeks if they don't use it. They are both retired so they drive much less. My father set up a quick connect for a battery tender without having to open the hood every time.

I told them they now have a plug-in hybrid

 

As an electronics tech that has dealt with data systems of vehicles for my entire career of 30+ years, one thing I can tell you is that modern batteries suck. Due to environmental concerns, damage due to accidents and the health safety concerns of the chemicals, new batteries are pretty much the equivalent of acidic fruit juice.
If you have ever seen an old battery leak onto metal or the pavement it eats away at it pretty quickly. Not so good from a health and safety standpoint. The side effect is that most new batteries in a combined weather ( 4 seasons) area will last about 3-4 years but will lose considerable cranking power after 2 years. Maybe in states that do not have winter you may get an extra year but bank on replacing the battery of any car built after 2008 every 3 years.

 

new batteries in a combined weather ( 4 seasons) area will last about 3-4 years but will lose considerable cranking power after 2 years.

That's often the case but multiple other factors than what you mention also play a role : number of too short trip to recharge, car unused for long periods, condition of the car, temperature etc. With my driving profile, batteries last 7 years. At least it's the point I change them anyway, preventively.

 

See my other thread in which I just retired a Costco battery that had lasted almost exactly 7 years. Maybe what you're saying might be true, but not in my case.