Lithium jump starter packs

Posted on 31 Mar 2015 by

Jump packs - portable battery-powered jump starters to get a car running when the main (cranking) battery in the car can't do it alone. First of all, let's have a look at the situation:

An average car battery weighs about 15-20kg, gets recharged every time the car engine is running, and a good one lasts several years before it needs to be changed (demise eventually caused through natural decay, unless the owner helps it along).

An average jump pack weighs around 7.5kg, of which about 50% is the battery weight typically, and they usually sit in the garage for months without charging and, when they are called on to do their boogie, you'd like to feel confident that a badly maintained battery of about 1/5th the size of your standard car battery can get your car engine leaping enthusiastically into life. That's probably enough on that, other than to say that it should be clear that buying a cheap jump starter is most likely an act of faith, and a waste of money and, if you want to feel confident about your jump pack, you might want to invest in a good one, rather than hope that you found the golden fleece of battery packs - something that is really cheap AND really high quality.

So, the poor old lead acid battery in a jump pack has to work hard when it is called on to work at all, and the industry has been looking for an alternative...

...which it found, around 2011, by using lithium batteries instead of lead acid. Lighter, able to deliver current much more quickly, lower self-discharge rates when left idle, and only one small problem, so small that salespeople haven't bothered to mention it much, and that is that when a lithium polymer battery is distressed, overcharged, overdischarged, punctured or otherwise traumatised, it tends to combust very quickly in a chemical fire - which is very hot and very hard to put out.

We've kept an eye on the evolution of these jump packs, and steadfastly refused to sell them up to now, because the market is flooded with rubbish that wouldn't pass any decent safety test, wholesaled at ridiculously low prices (we can buy the cheaper packs for less than $15 each, and the same things are retailed by "reputable organisations" for around $150 each). Rumours abound of fires, cover-ups, cars burned beyond recovery as a result of jump-packs catching fire in glove box, product recalls, compensation and gagging-orders, and so it goes on. If you'd like to see what one of these things does when it goes up, have a look at the video at this LINK - this is a jump pack left attached to a battery in a workshop in America. The fire is quick, and intense, and you can imagine what would happen if someone was nearby, or holding the jump pack, when it happened.

The basic problem is that these lithium packs weigh maybe 10% to 20% of what a traditional (lead acid battery) jump pack weighs, so the designer is looking for a colossal release of power to start a car, delivered very quickly, from a very small battery. It's possible, but there aren't any free lunches here, so the penalty is that the pack designer has to work hard on protection circuits, fire-proofing and quality material selection - or not - as they choose. The basic idea is that a battery of around 1/50th of the weight of a car battery is being called on to do the same job. Blind Freddy could see that is not going to be easy.

So we've been waiting for a reputable supplier to offer us a jump pack that they are happy that we destruction test, knowing all of the above, and being up-to-speed with the way that lithium polymer batteries behave, and misbehave. Our basic requirement, as a minimum, is that the designer and manufacturer will have considered, and dealt with:

  • automatic power shut down to save energy and handle battery distress
  • repeat performance (a bad car battery usually means more than a quick burst of energy from a jump pack)
  • recharging options, to avoid the pack being neglected due to complex charging options
  • reverse polarity protection
  • overheating protection
  • over-voltage protection
  • over-charge prtoection
  • over-discharge protection
  • overload protection
  • drain back protection
  • short circuit protection
  • thermal runaway resistance
  • response speed in a shut-down situation
  • stand by time and battery life
  • design and size for purpose
  • fire proof and spark proof build
  • case design for protection, longevity and containment

It has taken about 4 years of waiting, but we've finally found the lithium jump packs that we are happy with. They're not cheap, but they are good value, and they are suited to the demands of a workshop or similar high-use environment. We've seen the test results - the effects of huge power demand, repeated heating in a cooker, and we've subjected them to our own testing to ensure that they are something that we'd be confident and happy to own, because that makes us happy to sell them to other people too. They are from Battery Fighter - a highly trusted brand in the battery electronics market place - and we'd be happy to show you how they work, and why they were worth the wait.