Can leaving the door open run down the battery and am I going to recover from 5.5v

you can certainly try a jump, but i wouldn't trust it. i'm surprised the jump pack didn't work. triple a put one on my 4.4v and it started fine.
as to a replacement, there's no consensus, because there's no testing or data

 

Most batteries can tolerate a limited number of such experiences, and come back sort of ok if given a nice long slow charge. (Not trickle, that's too slow, but ideally under the labeled limit on the battery of 3 or 5 amps or so, which means a good solid overnight up to maybe a full day on the charger).

After that it might show some signs of degradation, or it might be trouble free for a long time, as long as you don't keep doing that to it.

 

I just replace my battery today (see new post) . It was dead as a door nail but I had no problem starting it with my little jumper pack. As long as there’s enough juice to energize the pass over relay, it should be ok to go. I drove it to and from the dealer where I bought the battery with no problem.

 

try disconnecting the battery and using the jump pack alone

 

You jumping directly the battery or the jump point under the hood?

Also, was it the drivers door ajar?
wonder if the brake pressurization was occurring every so often?

 

If the battery is in a really low state, the brake pressurization will stay running due to it not being able to reach shut- off pressure. It’ll run until the battery is completely dead

 

circle of death.... /

 

I have vague memories -- don't ask me to document it just now -- that leaving doors ajar keeps some additional monitoring circuitry alive, not just the lights. So lower current LED lights, or lights completely off, buys more time but doesn't cure the problem of eventually draining the battery.

So it is not just a coincidence.

 

On ours at least: open a door and there's a light in the door panel that goes on, plus little puddle lights in the front footwells. Neither have off switches.

12 hours is enough to seriously deplete the battery. Time for a smart charger session.

 

My experience with a run down battery (although it was certainly not as low as 5.5V) was that attaching a 2A 12V power supply to the charge terminals under the hood made it start right up.
No idea why attaching a portable jump starter would fail, unless maybe the 12V battery is FUBAR.

 

A jump starter takes the place of the battery, to get the car started, and once the car is started you could practically remove the battery from the car, and it would still run.

But that in no way restores the battery. With a seriously depleted battery, if you jump start it go for a short drive, stop and shut off the car: you're pretty much in the same spot you were at the outset.

Ok, I think I misunderstood you. You're saying no idea why the jump starter would fail to at least start the car? I'm with you there.

Still, I think a lot of people conflate "jump start" with "my battery is fine now".

 

I went OEM and am not disappointed. The battery I pulled after six years still holds a very nice charge and I use it in the camper.

 

A jump start does NOT replace the battery, it supplements it, since it is connected in parallel.
And leaving the jump source connected for a LONG time, like an hour, should bring the "dead" battery at least partially back to life if it is not permanently damaged.

And for the OP: You should NOT be using a "trickle charger" for anything.
I hope what you have really is a smart tender type charger.

The Optima's have had quality control problems. I would NOT recommend them.

 

Maybe even more so, with the less robust batteries on the Prius and it's ilk.

 

Way back when, the "voltage regulators" were more like voltage limiters and most generators and early alternators just blasted out something like 14.5 volts ALL THE TIME just to be sure. That is why adding water was more important back then. I have a motor home that still does that.

Modern electronic regulators are much better but the top end is now about 13.8 and that might take a LONG time to recharge a really flat battery......like forever maybe.

 

Plus a bunch of new always-on circuits (remote unlock, fob detection, computer memories) that are constantly pulling current, so today's cars are never completely off the way old cars were.

 

The thing is: a Prius has such low power demands starting up that just connecting a jump starter should be more then enough to start the car. It's not like any standard car that needs some 100A starting current to get the thing going.
So in my mind there is no need to have it connected for some time to first charge the dead battery and then start.