12 volt battery issue

Try this for a ground point:



Also this, from the always useful Mendel Leisk:

"If you have a multimeter you can sus out good ground points. Easiest is if it's got a continuity scale with audio feedback: beeps when you've made a circuit. Clamp one lead to a know ground, then go around touching possible ground points with the other lead."

Finally: It might also be possible to peel the two leads on the jump pack apart in order to get to more locations.

 

Yes. It may be recoverable, but you'd need to see where it's at, and attempt charging. One question though: how old is this battery? 4~5 years old, I would just replace. If it's the original battery, no question: it's overdue for replacement.

It's ok to charge without removal. Just be careful with connection, don't reverse the connection.

You've got to think through: what your priorities are:

1. A jumpstart pack, or jumper cables and a second vehicle, will get the car running, good for emergency use, when you're stuck somewhere, absolutely have to move it first. When ever using jumper cables and a second vehicle, connect the cables in this order:

a) positive cable to positive on dead car.
b) positive cable to positive on live car.
c) negative cable to negative on live car.
d) negative cable to ground on dead car.

Disconnect in opposite order.

Never: connect positive and negative cables just at one car, with the other ends loose. If the other ends touch together, you've just shorted out the battery.


A screen grab from Owner's Manual (starts at page 543:








2. A digital multimeter, or better, something like Solar BA9, will give you info about your battery's current state.

3. A smart charger, one that will initially check if the battery is even viable, then run a multi-stage charging process, and finish off as a trickle charger. 3rd gen, 3~4 amp rated chargers are optimum.

What I use:

Clore JNC 660 Jump Pack
Solar BA5 electronic load tester
CTEK 4.3 smart charger

For your immediate issue, the jump pack with short leads, this point will likely be ok too, and is very close to the fuse box:



But verify: a multimeter with a continuity mode (or just on a low resistance scale), touch the two points flagged in the above, see if there's continuity between them (low resistance). That'll indicate they're both grounded. I know the one on the left is grounded. I've used it for years. It's screwing directly into the cylinder head.

Keep in mind though: jumpstarting the car will not completely revive the battery; it's just a stopgap to get the car moved. You still need to test and charge (or replace) the battery.

 

Everything good, any dash lights or codes?

 

They recommend to charge up the pack when first receiving. Not sure if u did that.
Def charge it up fully now, and keep it in your Prius.
Perhaps @Mendel Leisk can post the current recommended 12V replacements
Im sure you will want to replace that sooner than later.
However it could last a little bit longer depending on age.

 

Not an expert here, but I have read countless times that batteries can only take so much stress.
So after it ages, and those stresses compile (not driving much, so not charged often, short drives)
(and doors left ajar with interior lights on and drains battery) and also multiple jump starts, etc...
Then at some point the battery can fail and not take a charge.

I have been monitoring mine and also have recently been trickle charging the most I can on both
of my Prius' since I believe both have been jumped due to door ajar etc.

But with a multimeter, they still both test around 12.5v or so after a full night
or multiple nights of no use. (also I dont open drivers door before test)