Battery jump packs what I learned the hard way
 

They apparently need to see some minimal voltage as a safety item to check correct polarity. Mine didn’t have an override for a really dead RV battery,so it wouldn’t release voltage to jump the RV batteries. Others have a manual safety override for really low batteries. About the same $ like $90-$100

From Amazon
Jumtop=no $91
Novo=yes $99

Yes. This feature saved me just last week when I used my Noko in a bad state of mind.

Interesting! Now I need to look into the Stanley JC509 I bought for my daughter. It has a warning for polarity and I'm not sure if there's an override.

What I learned the hard way semi related.

Battery died in wifes Tahoe.

Drove over in the boys KIA to jump it, NG.

Finally called roadside.

He shows up with jump pack. NG.

Just as I'm resigining myself to have it towed to the dealer the roadside guy asks if the key is in the fob.

As we all know push button start cars do still have a physical key that's hidden inside the fob so you can unlock a vehicle with a dead battery.

Turns out, it's also a security feature, if you don't return the physical key to the fob, **** no workie.

Put the key back in the fob, hit start, boom, life was good again.

Tipped the dude $20.00.

Man! How dead are we talking?

I had no idea. Just looked at my wife's 4Runner FOB and there is the key.

This is our first fob car and I rarely drive it...thanks!

Left a led light on for a month. Dead like 2 volts

Any modern tender/charger (eg with more electronics inside than a fuse, transformer, couple of capacitors and a bridge rectifier) won't do anything at all with a battery that registers less than 2V. I presume the jump pack is doing something similar.

You can use a power source that just doesn't care - like a bench power supply - to get the voltage up, or hook up another battery in parallel to get the voltage up over 2V. Either just leave connected to charge the original battery until it reads over 2V, or jump/charge the combined batteries.

Automotive batteries are not designed for deep discharge; unlike the "old days", they could be suspect after this, or not really recoverable. I've had smaller AGM batteries charge for 36 hours, read fine on a voltmeter - and immediately fail when re-fitted. YMMV.

Check the manual.

If the fob battery dies there is a "pocket" somewhere in the car, on the Tahoe and Jag both in the center console, you drop the fob in there and registers the fob so you can start the car.

As soon as she gets home!

There are some excellent videos on the "tube"...again, thanks. I don't think I have more than ten minutes behind the wheel of her 4Runner so I really was more clueless than usual.

When we picked up the car new, I just dropped her off and ran other errands.

These days, a car owner's manual is as thick as a Steven King novel. We should read them to learn the tricks, but most of us don't...

Hell, I thought I was being high tech by carrying jumper cables...I figured one of those battery pak jump gadgets would probably be dead when I needed it.

Funny, I just learned this (about an Impala we have at work) an hour or so ago.

Can you even jump a battery with 2V?

I am sure iobilizer and security "features" in keys have caused way more harm than good in aggregate

Definitely need a safety bypass on the Lion jump packs, ideally they should be able to get the car going with no battery at all. Just an emergency thing to get you home even if the battery is toast.

I had a noco one prior. It bricked itself and they has tamper resistant screws to make trouble shooting much harder. Would never buy another. I have one of the Imazing cheap ones from amazon now seems to work well (Thanks Project Farm!)

Thankfully I learned about it before needing it.

Had the Tahoe a good year+ and every time I drove the wife on errands and waited in the car for her I'd hunt for a place that the physical key in the fob could be used.

In my head it made sense, they give you a physical key to unlock the car if the car or fob battery is dead so there MUST be a "traditional" ignition switch somewhere. It's only logical right?

Finally just googled it and found the answer.

My wife had been using the slot as a coin holder, lol

Another reason to get antigravity batteries.

Same goes for chargers on a really dead battery. My electronic charger will give a bad battery diagnosis and will not charge. If I hit it with my old school century charger, then the electronic charger will do its job after.
I have been looking for the larger Noco jump packs to have on standby. Anyone have any feedback on these as far as durability goes?