Preemptively replace 12V battery?

You could.

If you want to judge more wisely, just check the 12 volt battery before starting some morning: if it shows under 12, replace it.

There are more elaborate load tests possible, but the Prius does not usually have a high load. One way to impose some load is to leave your foot off the brake and push Power twice, that should activate everything electrical, except the power electronics.

 

Heck, eight years: I would. It's somewhat comparable to 10 year old tires with plenty of tread: yes, but...

If you want to do a decent assessment of it's health, look into Solar BA5 or comparable. They're a new generation of automotive battery testers.

I start window shopping around the 5 year mark, replace soon thereafter, just as a matter of course.

 

I would do to age

 

or carry a jump pack. handy to have, and you may save the cost with a few more years of your oems battery.
plus, better for the environment

 

200 hundred bucks is CHEAP for a dealer.

you can probably find something for $150., but when they tell you free install, then they see where it is, they usually balk

 

you do have to keep them charged. but the prius battery only fires the computers and relays, so it doesn't take much

 

The problem with most jump-starters is that they are lead-acid batteries just like a car battery, only smaller, maybe half the size or less. They can boost a marginally weak battery, but not a dead one. And like most car batteries, they're usually going to be toast in a few short years, use them or not. A few ridiculously small lithium-ion jump-starters are beginning to show up now. Only time will tell if they're going to be any good.

 

The fact that you are thinking about your 12 V battery I would replace it unless I have another car I could drive and really don't depend on this one.

A few of the repair videos I watch use Lion jump packs and they always work for them. You get what you pay for, they are not all created equal.

 

Install is not that hard. Unusual, but not really more difficult, and Prius have been around for a while.

I keep buying JNC660: one for myself, and two for our kids. They have an AGM battery, need a top-up every 3 months or so. You just plug it into a simple 12 volt extension cord to household current, and there's an internal automatic charger with indicator lights, for charging and done. The clore website allows you to set up a tri-monthly email reminder to charge them.

I've mainly have been jumpstarting our daughter's V6 Pilot, no problems. For XMas I got her the latest one, so I'm outa a job.

 

the dealer's battery is good and has a 84 month warranty (prorated).

This AC Delco is the cheapest I know of: www.amazon.com/dp/B010GKJ8F6

 

Yeah, and @bisco chimed in on this too: $202 plus tax (installed), through dealership, is pretty good price.

Pep Boys during their sales will do the Bosch (installed) for $150~160 plus tax, but dealership battery is debatably worth the extra.

For a counterpoint, when I checked in late summer 3 years back, the discounted price for the battery through dealership was $273 (no install). Several dealerships contacted, same story. I dread to think what it is now. Cheapest is a comparable battery through Canadian Tire, and last time I checked it was a bit over $200.

Addendum: oy, $245 now.

Automotive | Canadian Tire

 

I like the Toyota battery. It's what I got when I needed one. You can find cheaper, but I doubt yo'll find better. Look how long your original is lasting. And you got a good price even if you need to instal it yourself.

 

I wouldn’t. Push it to 9 years for bragging rights in here.

 

There’s a test procedure that is not difficult to follow if you have a multimeter, and possibly a charger.

After driving/running engine shut car off. Turn on high beams for 30 secs to remove surface charge. Measure voltage at battery terminals: 12.5 V or higher and battery is still good. 11.0 to 12.5 V recharge. Below 11.0 V replace.

I know there’s debate on the proper amperage rating of the charger. But follow the suggested maximum charging rate that is listed on the battery. Charging follows V=IR. To get a faster rate the charger has to load the battery with a higher voltage. If you don’t follow as listed (it’s max rate is actually on a sticker on the original battery), you may have a false test result. I tried it....

 

8 years? yep i'd be replacing it if I were you. Esp living in MN.

 

Pepboys currently have the Bosch Premium Performance Battery Group, Size 51 | 647478 | Pep Boys for $181.99 - 20% off and -$40 mail in rebate. Free install, 48 months free replacement, 96 months pro rated warranty and 3 yrs free emergency jumpstart.