I had my glove box light completely kill my car battery when I left it for 2 weeks. Now it may be a 4 cylinder but it's also a diesel. The jump starter I had from Costco couldn't handle the glow plugs and starter at the same time but once I waited for the glow plugs to cycle and turn off it started just fine.

These little starter packs are pretty handy and work well if you get a decent one. Do not judge them by size, they get it done. That said, given they are $27 and ship from overseas and ebay has no product rating, I will pass. There are lots of versions on amazon in the $50 range and at least there you have amazon and buyer reviews to make an informed decision.

FWIW, I bought a similar unit last winter on Amazon with a SlickDeals code for $19. Only tried to use it one time, on my GMG Sierra with a totally dead battery, and it wouldn't turn the truck over. I'd still like to try it on a more typical "low" instead of "dead" battery, but until then, is reserved for emergency phone charger duty.

https://www.amazon.com/gp/product/B00FD ... UTF8&psc=1

In my experience these will not turn over a 100% dead battery. But they will start a vehicle with a little juice left.

That said when a battery is 100% dead even the bigger jump boxes will not be able to start it. Heck sometimes I've used two cars to quickly jump a completely dead battery.

And usually 100% dead will mean you need a new battery and was not caused by a light left on. Proper battery inspection and replacement will help avoid issues.

As ive stated these come down to quality and well that usually means spending more than $20 folks. Ive started plenty of vehicles with discharged batteries, as in no dome light even. Now a bad battery can be a different story but its not uncommon for these to do their thing anyway and get the vehicle started and again size and quality are a key factor

As some have stated if all it cost was $20 then probably all its good for is charging the cell phone....just saying

I'd like to find a nice portable charger.

My 2002 Silverado diesel needed to be jumped once in 14 years.
Somehow a hand held spotlight was bumped and left on overnight.
100 amp Schumacher charger/booster couldn't jump it.
Had to leave it on max 15 amp charge for over two hours to get it to turn over with the 100 amp boost.

But my truck does have two pretty big batteries.

^^^^^ because they are handy for more than just jumping id look at Antgravity's XP-10 (its their biggest currently as far as I know) I have heard they may be working on a bigger one more specifically for diesels but the XP-10 is capable of starting even the diesel trucks, bad batteries not withstanding but it will do it.

look at reviews etc to get a feel for their products and quality, its neat shit

Here's our thread on the XP-10:
viewtopic.php?f=34&t=63777

Costco has one to at $60:
http://www.costco.com/Lithium-Jump-Star ... 12116.html