Turn off, on, off again without opening door causes beeping that drains battery in under an hour.

After the second jump start you didn’t start thinking you needed a new battery?

After the first time you killed it by leaving a Light on or hatch ajar it was a done deal. The battery was ruined. If the battery discharges using a light bulb it does it so thoroughly sulphation occurs quickly rendering that battery completely untrust worthy. You can keep jump starting it may be good for a while but then it will go dead again.
What’s amazing is AAA didn’t total the car out jumping it. There’s post after post of AAA causing major damage to a Prius jump starting it. They provide so much jump power there’s a huge inrush of dc current the car was not Designed to ever see. You can jump start a Prius with a drill battery.

 

The traditional clue that a 12V battery is weak is that the starter slows down or even refuses to turn the engine over. Prius doesn't even have a traditional starter, so that clue isn't available. The primary purpose of the 12V battery in a Prius is to boot the computers. Once the car is in READY, even 12V power comes from the big battery via a charging circuit in the inverter.

So the usual evidence that a Prius 12V battery is weak is that a computer goes wonky. It's all a matter of which computer is the first to hiccup at lower than normal voltage.

The best way to test the 12V battery voltage while the car is OFF, or in IGNITION ON mode. Anything under 11V is asking for trouble.

 

What's surprising here is that you can fit so MUCH bad information into such a short message.

It is not a given that a single deep discharge event will ruin a battery......especially not one of AGM design.
It depends on the depth of the discharge and the length of time involved.
Typically a single deep discharge event with an AGM battery that is fairly new will NOT cause any significant loss of life expectancy.

If there is any "huge inrush of current" when jumping, it would be going to the old battery which still is in place.
Otherwise it's no different that replacing the battery and connecting a new one.

 

12.0 is 70% discharged.
11.0 is way beyond asking for trouble.

 

BACKGROUND: I'm getting a new battery for my 2007 prius for similar reasons. I've only owned the car 4 yrs, and already replaced the battery once (2017 -- after several months of using one of the larger portable battery chargers).and was doing fine till last year.

When my car sat for weeks on end ( when everything shut down) .I got a jump from a neighbor, but was unable to get the battery to hold the charge no matter how long I drove it. Now I understand why!

Funds were short and wasn't driving much, so got a Taklife charger, to tide me by, and have been using it to start the car ever since. Only NOW I am finally able to afford the new battery and want THIS one to last longer than 3 yrs!! Good info here!!

MY QUESTION: God forbid I would need to jump the new battery at some time.. but stuff happens. So I'm particularly concerned about protecting the battery from the "inrush" of too much current that folks are talking about here.

Is this a danger even with handheld chargers like Taklife sells? Again, God forbid I should need to use it, but do I need to get a different handheld unit??

I've never posted, so can't post a live link to the product I have so here are the specs (vebatim from Amazon) and screenshot of the product.
800A Peak 18000mAh Lithium Car Jump Starter for Up to 7.0L Gas or 5.5L Diesel Engine, T8(Orange) 12V Auto Battery Booster with LCD Screen, Portable Power Bank with USB Quick Charge

 

@kc&her07 :

1. what’s your usage, say miles per month, or year?

2. Will your car have protracted periods of no use, day weeks? How often?

3. do you have secure parking with AC outlets?

 

Unfortunately, I hit all the wrong answers:
1. I drove 7k a year normally, but nothing normal about the last 2 years or our present reality.
2. I'm unemployed, so go out an average of once a week for errands etc
(pre pandemic 3x +/week with errands, church, get-togefhers etc) All short trips (5-10miles) which I'm just now learning here is not enough to keep things charged properly.
3. No secure parking. Apartment complex with with carport type covered parking, (which my balcony directly overlooks.)

 

One thing, that's a jump starter, not a charger (song in there...?). Hmm:

What mostly drains an idle battery is being connected; the car imposes a constant low-level demand for electrons. This might help, but a bit awkward:

Install a breaker switch, somewhere along the neg cable, between the post and ground. There's switches made expressly for this. I believe there's some that you can open/close with a remote control; that would be most convenient.

With a manual switch, when you've left the switch "open" (no flow), once you've done that, the car is dead/unresponsive. Then to get back in you would need to do something like this:

1. Open driver's door with physical key.
2. Pop the hood.
3. Connect your jump pack, at the under-hood jump point (it gets some use )
4. Don't touch anything else, just go straight to the hatch, open, and close the breaker switch on the battery.
5. Disconnect the jump pack.

This is not ideal; you will lose radio presets, trip meters, and it does some behind the scenes resets-to-defaults of other stuff too. But it'll work.

Alternately: maybe an on-board style charger, permanently wired to the battery, and with a quck-connect? Would it be possible to run a semi-secure power cord to the car?