Vector doesn't hold a charge.

You did not say what is wrong. Might need a new one.

I know how you feel because I had the same problem with mine until I read about the procedure.
Most of those Jump start chargers unfortunately require that you charge them when you buy it and then maintain the charge at least once a month.
There is usually a light on the charger to indicate that the charger is fully charged.

I advise caution when using a standard battery charger to charge a jumpstarter via the main leads. Firstly if there is polarity protection it probably won't work and secondly the heart of the jumpstarter is a sealed lead acid battery which does not usually tolerate high charge currents without shortening the life of the battery.
This type of battery needs either the low charge current supplied by the original charger or similar or a sophisticated regulated charger.

If using a standard charger avoid using a high performance type and use only the type that provides a trickle charge.

How old is it? The battery only lasts a couple of years used or not.

http://www.baccusglobal.com/bd/manuals/NEW%20MANUALS%20FOR%20WEB/VEC012POB%20MANUAL.pdf

Take it apart. The battery inside has corroded the wires at the terminals. Replace ends clean and put protector spray on them.

The battery is probably too old to hold a charge. http://www.baccusglobal.com/bd/manuals/NEW%20MANUALS%20FOR%20WEB/VEC012POB%20MANUAL.pdf

Hi.

The Vector jumpstart system listed does not use a power adapter. Replacement parts such as cords and clamps can be obtained calling the toll free number: (866) 584-5504.

Regards.

NO, you will destroy your charging system if it is left on after starting.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/matt_8dbc24bf722649ac

no you can use a 1 amp or greater but not less that 700ma