Another 12V failure

Project Farm tested quite a few and found the Gooloo GP4000 to be good for the money(currently on clearance sale for $90). I'd tell most people to go with a smaller unit like the GP2000 to save some money, but you might need a more powerful unit because you need it to work in extreme cold. Pretty much all of the consumer-level units lose a huge chunk of their capacity at low temps.

A top NoCo(GBX155) tested better, but was 4x the price($370).

I've been using a NoCo GB40 for the last several years. It usually gets the job done, but it's failed me a couple times. Usually when very cold(-10F to -20F) and sitting unused for a couple months. If I was buying again, I'd probably consider one of their more powerful units, or at least a GBX45 instead of the regular series GB40.

You can often find good deals on boost packs during Black Friday/Cyber Monday sales.

 

FWIW; that jump pack isn't going to work if you pull it out from under your seat in -40F. You need to drag it inside with you, if you want it to work.

 

Another option for extreme cold situations is a capacitor-based jump pack. They can harvest the low current from the "dead" battery, boost it up, and then deliver it back in a burst to get you going. They can also be more quickly charged using standard methods, but they don't hold their charge as well as Li-Ion, Li-Po, or LFP options do. Increased cost and larger size are some of the drawbacks. Depends on how critical a person's situation is.

 

i got a deal on a noco gb 20 or 30. you don't need much to start a prius, but you want one with an override button in case the battery is too low. they need to detect a certain amount of voltage to work otherwise.
the override bypasses the reverse polarity feature, so you have to be careful

 

I haven't had any 12 V battery issues in quite a while but had plenty when I first got my Prius Prime XSE premium. The practices I have changed.

1. Keeping the car in ON instead of Accessory mode if I am going to be in the car. This keeps the traction battery supplying power to the 12V auxiliary battery.

2. If I am going to plug in and don't want to have to unplug when charging is complete I leave the car in room mode and lock the doors with the physical key. You need to turn off the headlights and climate control if you don't want to use excess electricity when you are away.

In my experience most of the trouble I was having was due to leaving the EVSE attached to the car after the car had completed charging. Puts the auxiliary battery in a depleted state where little extra uses of it cause it to die. I credit those two changes to me not having any 12V battery issues in over a year.

 

I think you probably mean keeping it in READY.

Unless gen 5 has changed this, you can choose from OFF, ACCessory (one button push, no brake), ON (another button push, no brake), and READY (button push with brake).

READY is the only choice that will keep the 12-volt battery charged. ACC will discharge the 12-volt battery, and ON will discharge it even faster (because more of the car's electrical loads are being powered).

 

You can see in this WebAuto youtube video that as soon as he powers on the Prius Prime current begins to flow into the auxiliary battery from the traction battery.