Battery Life Extension Ideas?

Is it a 10 year old battery? It may be time to replace it. You could keep the small emergency Lithium battery to jump start the car yourself.

With a 10 year old car I would be more concerned with Main Hybrid battery when keeping the car unused to 3 weeks.

I have a 2005 Prius. I am leaving it with a friend to be used while I am away for 10 days. This car needs to be used regularly. More particularly as it gets old.

 

Battery tender. It charges your 12v battery while your car sits for days or weeks. Unfortunately the worst thing for all Priuses are sitting around not having the main hybrid charging. The only way to charge the main battery is driving it.

SM-J737T1 ?

 

Well your 12v battery should be able to go a few weeks without use and still power up the cars electronics when you’re ready. There is a small button under the steering wheel that turns the smart key on and off. You can turn it off to have less draw on the 12v, since the car is always looking for a key! You can use the physical key to unlock the drivers door and put the key fob in the slot to start it.

 

congrats and welcome!
now might be a good time to consider a prolong hybrid battery charger, but if you are leaving the car in a lot with no available electrical source, you probably purchased the wrong car.

 

I agree with @bisco

If the use of the car is gonna be the same for a while, like years that way,
may be best to get a Corolla or even an older Lexus.

Otherwise, just carry a cheap jumper pack with you ($30~$50), and jump it safely when needed.

 

THAT doesn't bode well for the future.

A Prius with the SKS turned off will be no more likely to have a problem starting after a 2 week "nap" than most any other car.
IF you drive it enough when you DO drive it.

A solar battery tender would be ideal IF it is parked in the sun.

Not starting again the day after driving it for 2 hours tends to indicate that the battery needs to be replaced.......no matter what the test showed.

 

to be honest a lot of these "my battery is bad" stories remind me of my own personal "my battery is bad" story - which was in fact not the battery but the failing combination meter which i eventually replaced with a refurb from texashybridbatteries. the confusing part was that unplugging and replugging my battery would temporarily allow me to start the car sometimes... until one day it didnt.