How long has your original 12v battery lasted?

Still dealing with Chipmonks loving interior of my Prius

 

About 8 years and 10 months @ 150k miles.

 

I am at 86k miles. The battery is 7 years old (maybe 8). It's the smaller 35 Ah version and recently sits low around 12.2-12.4V
I was going to get a new one but instead, I will try to add some water and charge it properly. Looks like 2 more years is doable.

On the other hand, I am going to do brake fluid change and the old battery may not be good enough with the IG-ON for that long.
Also, it looks like I am losing mileage because traction battery got drained to charge the 12V so it may not be worthwhile.
Plan B is to install a 55 Ah deep-cycle battery.

 

You could hook up your charger as you do the brakes.
Should be enough to even charge the battery. It won't take 4 amps for the brakes,
at least I don't think it will take 4 amps for the brakes....

 

P.S. The aftermarket replacement lasted just 2.5 years.

I did keep the OEM after I replaced it. It powered a small; inverter during a couple of power outages. It ran a phone charger, a coffee machine, and a lamp.

It is an excellent battery.

 

I've got two of the original Yuasa, one from a 2006 and one from a 2009, they've been powering one of my UPS for a
couple years now.

 

2015 Gen 3. Replaced battery two weeks ago at 123,500 miles, with OEM battery from Toyota.