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Wednesday, March 21, 2018

Mini, Battery Powered, Engine Jump Starters And Power Banks

    I wrote an article last week about wireless and USB charging battery packs. They work pretty well, all things considered. Some nice folks commented about Lithium Ion battery based engine jump starters and I promised them an article about them. Well, here it is. Everyone knows I tend to be an early adopter of new technology. A couple of years ago I purchased a very small Li-Ion jump starter from a (mostly) reputable source. It was tiny and boasted it could easily start a V8 engine, though not a diesel. I was sold. Did it work as advertised?

It's Only 1/2" Thick!
Let's take a look at the one I bought first then move on to much newer (and better) versions. The one I have has an 8000mAh batter (8Ah) and in addition to regular jumper cables on a 1 foot cord it had a port to charge any device via full size USB. Add that to a bright white LED flashlight all in a package a bit bigger than a deck of playing cards and you have the idea. I carried it in my motorcycle "trunk." Yes, I said, "trunk!" I have a Honda PC800 Pacific Coast, look it up! It lived there unless I was taking a trip in another vehicle, then I brought along just in case. It all fit in a small neoprene bag with a Velcro closure that I had sitting around. I have NO idea what that bag came with...

The White Dot Is A Super-Bright Flashlight
To charge it, they provided a wall charger and a cable to charge from your computer's USB port. It took a long time to charge...about 14 hours from dead. I made sure it was charged regularly. That was allegedly easy, as it had 4 blue lights on the side that all illuminated when it was full. The first time I used it, it worked OK. Not great...but it did start a 3.9L V6. Then I didn't use it for a few months after recharge. I was off to pick up an SUV in Pennsylvania, about three hours away. When we wouldn't start, so the seller jump started it from a conventional lead-acid battery pack, no problem there. We figured it would charge from the alternator on the trip back. After 1.5 hours we made a gas stop. Shut it down (First Mistake) and it had a dead battery. Aha! Perfect time to use my micro sized jump box. Except after it was hooked up (it indicated it had a full charge) no start. power coming from it at all.

Very aggravating. We managed to borrow a full sized jump pack from a tractor-trailer driver. Started right up. The rest of the trip was uneventful. When I got home, I immediately plugged in the battery pack and left it to charge. It wouldn't. Looked OK...voltage from the charger was just didn't work. I'll be taking it apart soon enough to try and fix it (or, at least figure out what failed). Now I was on the hunt for another one. Bear in mind this is two years later and many large companies are offering them at reasonable prices (between $30 and $80). I've been looking at ones with decent warranty periods. Of course, many of these will be made in China. Not a problem in and of itself, but quality is usually a bit spotty. If you get a good one, it's great. If not...return it and try again.

This time, I will be buying one with a larger capacity. I have a V8 Gasoline engine (360cu. in/5.9L) in my RV, so the extra capacity will be useful, especially if my engine battery fails in cold weather. Of course, most RVs let you connect your house batteries to your engine battery temporarily for a boost, but this is a "just in case" scenario. Basically, it's peace of mind, with the added bonus of being able to charge (or run) your USB powered devices away from your RV.

Seems like a good idea, and since they are so small and lightweight, storing them will be a snap. I'll let you know when I finish my research and purchase an upgraded, more reliable unit. I still believe they are a great idea!

Be Seeing You...Down The Road,

Rich "The Wanderman"


  1. I purchased one from Harbor Freight and have used it 3 times with success. Ford v10 with a fully dead battery, it cranked over like normal. A real live saver if you are in the boonies.

    1. D Kittilson,
      Excellent! I will check on them when i get down to Harbor freight. Good tip!


      Rich "The Wanderman"

  2. Lithium shouldn't be pushed beyond about 30C, so your 6Ah pack puts out 180A max, for a short burst, without damaging itself. Smaller wires and other factors reduce that even further. To protect itself there's an inline fuse that will frequently blow very easily on an undersized unit so check that first if you have no power coming out to the jump starter leads.

    That said, you have to be REALLY careful reading capacity specs on these things. Many packs state the Ah at 3.8V nominal for the 18650 batteries - but in jumpstarting, you triple those 4.2v max cells up for 12.6V, thirding your capacity and C rating...your 6Ah pack now only gives you 60A bursts, which is almost useless unless your Pb battery is just marginal.

    Lithium is pretty powerful for it's size, but to start a truck you're still going to need a pack the size of a large Bible to save you.

    I know a LOT about these packs if had trouble and want to contact me, Rich.

    1. Wolfe,
      As usual, I learned something from you! I didn't realize (since I haven't yet opened the faulty one) that they are using 16450's. I have MANY of those lying around and some great conditioning chargers for them. Perhaps I can re-cell the broken one with good quality 16450's and be online again.

      Many thanks,

      Rich "The Wanderman"

    2. Yes, you can "recell" them, and in fact the one I carry came (intentionally) without cells - case and electronics only and the user provides their own.

    3. Wolfe,
      Holy Cow! i just noticed you are in NY, about 4 hours away...we should get together, I'll wager we have lots in common. Did i mention I'm buying another Rotorway?

      Rich "The Wanderman"

    4. This confusion over Ah@3.8V also affects USB battery banks -- people buy a "10Ah battery bank" and find it only puts out 6.5Ah when charging their phone. This is because:

      10Ah @ 3.8V = 38Wh
      38Wh * .85 typical boost efficiency = 32.3Wh
      32.3Wh / 5V = 6.5Ah @ 5V
      So, that battery is legit if misleading.

      When you get a dishonest Chinese pack containing recycled or rejected cells, your 10Ah battery delivers *1*Ah at 5V... :-S

      When comparing packs price vs capacity, it's easier to compare Wh ratings, but you can still get taken by "too good to be true" outright fraud products like the $9 "150,000Ah" card-deck-size pack on AE. :-D

  3. Rich,
    I've owned several of these units for years now, and the single biggest issue is this: with a really DEAD battery (deeply discharged), a lot of the jump-unit's current starts flowing into the battery and NOT the starter circuit. If the vehicle battery is way down, it sometimes makes better sense to disconnect it, use the jump-unit, then reconnect it after starting.
    Greg Illes

    1. Greg,
      That is entirely logical and practical...should have thought of it myself!

      Rich "The Wanderman"


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