How jumper battery packs work?

[dominatrix1]

I have a question re how those car battery packs work that you use to jump start your car. I had to jump mine this morning as I needed to move it - but did not have time to properly drive it to charge it up again. It worked fine. I then found out I needed to move it again and as it had not properly charged I had to use the battery pack - however this time it did not work? Any ideas why ? (I have put the battery on charge again hoping it was just drained)

 

[Lashout_UK]

The jump pack is probably flat. Charge it up, see what happens.

 

[Haze]

Seems like OP answered his own question....

 

[Semple]

Depending on the size of the pack you bought and whether you use it for charging other devices, i.e. your phone. It's quite plausible that you've just ran out of juice.

If it's a reasonably decent pack, it will fail to work if the charge level is below a threshold due to the amount of current it draws when jumping the car.

 

[Deleted member 66701]

Why aren't you just fitting a new battery to your car?

 

[Rroff]

Normally you should get around 10-15 starts off an emergency booster but if it has been sitting around awhile (4+ months) since the last charge that can drop to 1-2 even if it is showing full charge.

Some of the cheaper ones just use a basic fuse or something to stop them destroying the cells inside if the engine needs a lot of current to start and might stop working after a single use unless replaced.

 

[bledd]

I love mine, need to fix a parasitic draw with my car, it goes flat after 4 days of not driving.

Noco jump pack starts it every time! Awesome piece of kit.