First timer - 12V Battery Replacement for 2017 Prius Prime - Questions

welcome!
absolutely untrue. you can lose some settings like radio presets and etc. the car sometimes gets set to factory default and has to learn your driving habits again, which may make it do something you don't remember from when it was new. but nothing serious will happen. they do make 12v memory savers that you attach to the cables first if you like, then it won't lose anything.
as far as safety, disconnect the negative cable first and make sure it can't slip back and touch the post.
then when disconnecting the positive, if you accidentally touch the wrench to ground, nothing will happen. just don't let it touch the negative post.
when installing the new battery, connect the positive, and then the negative.
it's all very simple, just take your time and use caution.
that's a great price on the battery btw.
here's a helpful video:

watch

 

When tightening the clamps, while there is a torque spec (somewhere..), you’ll be fine just using common sense. You want to tighten them modestly, not too much. Snug them down, checking till you can’t twist the clamp on the post, then maybe 1/8” turn more, for insurance. The rounds at top edges of the posts should be showing too: push the clamps well onto the posts. A simple 10 mm box wrench works good.

 

With battery terminals just remember Red + is always first on and last off. Then you will never have an issue. When removing terminals Red is always last off and first on. I skipped the last Toyota genuine parts dealer sale. It was in November for $150ish for the battery. After servicing my Prius a few weeks ago, my battery is now in fair shape instead of good. So the next Toyota genuine parts sale, I will be getting a new 12v battery.

 

they're just afraid, no good reason. but the monkey they send out to work on your car probably sgouldn't be working on anyone's car

 

Similar rule is applicable to hooking up and disconnecting jumper cables. You do ONE cable at a time, starting with the red cable, to positive posts of both the dead and helper car. THEN repeat with the black cable.

Typically the red and black jumper cables are bonded together, split apart just at the ends. This kinda encourages you to connect both red and black clamps at one end. Then wander around with the other pair of red and black clamps, inches apart, over to the other battery. (I watched Scotty Kilmer do just that, in one of his videos...)

Which you DON'T want to do. Tap that second pair of clamps together, and you've just shorted the battery, the one already connected.

If possible with those bonded together cable sets: pull them completely apart. When connecting the cables just take the red one first, get it fully connected, then go back and get the black one, repeat.

There's more to it than that, the order you connect each cable, and using a ground instead of the neg post on the dead car. But the previous is the critical stuff.

 

I'm not sure changing a 12V battery is the proper place to learn to do maintenance, if you've never touched one before. You can mess things up royally by creating an arc and shorting out very expensive electronics if not careful. Maybe start with replacing the engine air filter and cabin air filter.

Walmart sells an exact fit for $159. It's called the H4 or 140R on the shelves.

It won't mess up any car settings, other than the clock. I've disconnected the 12V battery on my 2016 several times, and this is the only thing I've had to reset.

Yes, for sure. You need to disconnect the negative (black) terminal first, and wrap it up in a rag so it does not touch any other metal parts while you are working on the other side. Then disconnect the positive (red) terminal. You don't need to wrap the red one because there is no more current flowing. This takes a small metric socket to loosen the bolt, then twist and lift the connector off the post.

Then you need another larger socket with a long extension to reach the bolt holding the battery clamp at the bottom of the pan the battery sits in. Be careful not to drop the bolt when you are removing the clamp. Then it helps to have another set of hands to hold the battery cables out of the way while you lift the old battery out. Same for putting the new battery back in place. Then reverse your steps: replace and tighten the battery clamp to the bottom of the pan. Then replace the positive/red terminal and tighten the nut on the clamp. Then remove the rag from the negative terminal and secure it back on the negative post. I always try to quickly put it back on so as not to create a spark.

Good luck.

 

Yes, but...I express it as, "The black negative cable is first off and last on." The reason is that if your wrench working on the bolt for the red positive cable clamp touches the cable and the car at the same time you'll get a huge arc. Avoid that. Removing and tucking away the black negative cable first takes the car's body out of the circuit and removes this hazard.

You will need a lifting strap to lift the battery out of the holder. Less than $10 at an auto parts store. You'll want a battery post & cable clamp cleaner circular wire brush gizmo, under $5. Give the cable clamps inside surface a good circular wire brushing (in one direction only) until they're bright. If the cable clamps are still too tight on the battery post after you've loosened the clamp bolt, you'll need a $10 battery terminal lifter. There is only one bolt to loosen the cable clamp. Other cables are bolted together at the clamp; there is no need to unbolt any of these.

The batteries are filled with dilute sulfuric acid. DO NOT SPILL IT. DON'T LET IT TIP OVER INSIDE YOUR CAR WHILE YOU'RE DRIVING HOME. Return your old battery to the place you bought your new battery or a proper recycling location.

The battery I chose is the ACDelco LN1 AGM (absorbed glass mat) sealed battery, $151 mail order from Summit Racing
ACDelco 88866037 ACDelco Gold Automotive AGM Batteries | Summit Racing
AGM batteries are longer lived than a standard flooded cell lead acid battery and a perfect fit. While the Toyota branded batteries are perfectly OK, they are nothing special. The size that fits is listed as either 140R, or H4, or LN1. All drop right in, correct size, correct capacity, correct terminal location. I just looked at the O'Reilly auto parts batteries...$160 to $250.