Can't use powerbank jumper?

lavachickie · Aug 30, 2021

My Subaru Outback 2.5L 2014 seems to drain a battery fairly quickly if you leave accessories on. While it's only happened to me twice in four years, I wanted to be prepared should it happen again. (And yes, I had the battery tested, then replaced it proactively even though it wasn't bad before this past winter. I'm kinda like that... thanks to my Dad!)

The last time AAA came out to jump it, I noticed the unit he used was like half the size of a briefcase. He said yeah, you could even get smaller ones at Costco, and they could get you out of a pinch.

So to Costco I went, and picked up the "TYPE S 12V Jump Starter & 8000mAh Portable Power Bank." [link]

Then I proceeded with the experiment -- left the car in accessory mode with door open and fan on as I went about some front yard work. When I came back, battery drained.

Hooked up the unit according to instructions, and it would start to juice things, and then within seconds the display on the unit would say, "Battery protected; please disconnect and begin again." After doing that a few times, I gave up and jumped it with my Jeep. (No insight into the meaning of that message within the unit's own instruction manual.)

So... any idea why? And do I just need to buy a fancier unit... or... whut? This is a vital piece of my emergency car kit.

Amy

seagrass · Aug 30, 2021

If the battery that is flat is below around 7 volts the jump packs will typically not work.

Some of the newer jump packs have a small button that you need to push that momentarily overrides a battery that is below the threshold. This button will typically allow the vehicle to be jump started.

Hope this helps,

Seagrass

HKshooter · Aug 30, 2021

I'm not sure. I have one with no read out but the instructions indicate the thing is designed to be it's own nanny, every safe guard and protection imaginable is built in to keep the user from burning it up or FUBARing the car.
BUT! It has an emergency setting that bypasses all the nanny crap if an emergency calls for it.
I'm guessing your unit sees a battery that it too far dead to be of any help to start the car and senses that the required amp draw could over load the thing, causing it to over heat.
To the best of my knowledge these things aren't designed to start a car alone, they are designed to help a low battery start the car. If the car's battery is too far gone the draw on the unit may destroy it quickly and they want to avoid that.
My .02
ETA: Before I learned leaving the key in the ignition of my 2016 would kill the battery, I did so and killed my battery. Someone at the event had one of these little jump packs and it started my 3.6 after letting it sit hooked up for a couple of minutes. Dash lights would come on but when I turned the key to start, nothing. The little pack worked.

SilverOnyx · Aug 30, 2021

Costco has a generous return policy and they do sell more powerful jump starters online.

https://www.costco.com/duracell-1100-peak-amps-bluetooth-lithium-ion-jump-starter.product.100515297.html

HKshooter · Aug 30, 2021

Thanks for this, just ordered three.

Can't use powerbank jumper?

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