Thread: Mini Jump Starter

this is the one i own
JumpsPower AMG6 Pocket Jump Starter
i have never used it in anger
cost me 70 or 80 bucks.


this vid is starting a subaru
not sure if its a 2l or 2.5l


[ame]https://www.youtube.com/watch?v=LpduEXPyoA0[/ame]



this vid shows it starting a few cars, one after the other

[ame]https://www.youtube.com/watch?v=sMQN7FEU_sk[/ame]

OK thanks guys, armed with all this, I think it may be worth getting, I've put up the Your 4x4 episode 115 below if you're interested in seeing one of these mini jump starters work on a 3.0lt Isuzu turbo diesel, it's 5 mins in, the episode is not very good, trying to get to fancy with their editing I think, also all the other episodes of this Kimberley trip are also a bit average, I was hoping I could some ideas from it, but it's like a lot of their stuff, just one big ad.

Anyway here's episode 115, go to 4.55 for the mini jump starter bit, if it doesn't start at that point.

[ame]https://youtu.be/kk1s4I5jNI8[/ame]

Baz.

Originally Posted by Tombie

They work because Lifepo4 can pack a hell of a punch for a short time.

What can they be discharged down to safely?
Wondering how long a 50 A/hr version would run a fridge..
ie, normal practice is that there's about 50 A/hr of useful/safe capacity in a typical 100 A/hr lead acid battery before the battery doesnt like it.

The other thing I'm interested in is the charge rates that these things can accept, can they take higher rates than a lead acid battery?

bThey are good little things but they have limitations.

first off they work because lithium like nicad batteries can dump all their available power as fast and as hard as their internal construction will allow. while as little as 10AH doesnt sound like much but when you dump all of it in under 5 seconds its a lot, a lot of lot.

The wires are the size they are on these units as the first form of protection on the battery, as they heat up the resistance increases so the current draw stabilizes.

Generally these units dont carry the full current required to crank an engine they make up the difference between what the battery can provide and whats needed to keep the ECU/ignition working while the engine is cranking.


Be careful of the show pony tests, they're loaded, generally all the vehicles will have been stated and have warm engines and the batteries be low on charge but not dead flat. I've even seen one test done where the battery terminal protectant was only cleaned off of the places where the clamps were being attached and the multimeter reading was being read off of the still gooped posts. Mr demo man was less than happy when I caught him on slight of hand moving the probes to under the clamps to show just how much power the jump pack was pushing out. The other trick is to have a load on the battery when they do the initial reading.

I've no doubt whatsoever though that the good quality ones will start a warm modern diesel with no other power available. Heres why.

CCA.

CCA how many amps (average) your battery can push at -18degc for 30 seconds while maintaining a battery voltage of higher than 7.2V .

What if you don't need it for that long? lets say you need twice the CCA amp rating but for only 1/10 of the time to achieve a start? lets say at room temperature your battery can provide 10000A for 2 seconds but after 4 seconds to the full time its only pushing out 300Amps and when its cold those numbers halve. your jump pack might be lucky to get a 150CCA rating.
Go out and with the car unlocked and ready to start time how long it takes you to go from first pushing the key into the ignition and turning it to the start posiiton to having the engine running. If you have one of those fancy push button start jobbies count it from the time you get the proximity indication to the time it starts and then add a second (to allow for all the security stuff to work)

did anyone go past 5 seconds? did anyone have the starter crank for more than 2?

and heres the difference between your lead acid technology battery and those lithium ones. your lithium can dump every thing at once it will spit every erg its got in one go it will only pass the CCA test once before its flat. With a lead acid battery you cant so if you let the battery sit for a little while it will let you have another go at the CCA test.

but then none of that counts once the engine is running. because then all the works done and the alternator is doing its thing.

As for the running a 3 cyl fergi all day.. Not surprising really, they're a mechanical diesel, once its started you only need enough power to keep the fuel solenoid open, something like 150 mA If its the older version you dont even need that.



Id get one myself if I didn't have a rock solid dual battery system, a solar panel, enough cabling to remote power from the vehicle, a back up charging system, a set of jumper leads and an old school manual that I can push start in 5 degrees without a battery.

In the opposite way that Baz would be offended if you bought him a generator to use while camping I wouldn't be offended to receive a quality one of those jump packs as a gift.

I would also happily get one as a present as a battery tank/backup starter for someone who do extended time away from mains power but want or need (kids) to power up minor electrical gear (media players/small lights/radios) and wanted one (assuming they were on the gifting list in the first place)

But a big safety tip. Once the engine is started DO NOT leave the alligator clips attached in an attempt to fast charge the pack. Bad things happen. The same applies for the larger SLA packs but they generally just have their life shortened and dont emit kill you dead bad gasses or catch fire.

Originally Posted by mark2

What can they be discharged down to safely?
Wondering how long a 50 A/hr version would run a fridge..
ie, normal practice is that there's about 50 A/hr of useful/safe capacity in a typical 100 A/hr lead acid battery before the battery doesnt like it.

The other thing I'm interested in is the charge rates that these things can accept, can they take higher rates than a lead acid battery?

I think I read in the specs of one of them that said they maintain 80% of their charge, if that's the case it may not run the fridge for as long.

Baz.

PS; thanks for all the great info Dave, I did know about not leaving them connected after starting the car

Originally Posted by mark2

What can they be discharged down to safely?
Wondering how long a 50 A/hr version would run a fridge..
ie, normal practice is that there's about 50 A/hr of useful/safe capacity in a typical 100 A/hr lead acid battery before the battery doesnt like it.

The other thing I'm interested in is the charge rates that these things can accept, can they take higher rates than a lead acid battery?

from what ive read, you can take them down to 20%
and they can take a higher charge rate.