My portable jump starter is this one from Cen-tech:
I've had it for about 12 months and used it a few times shortly after I got it. However, I haven't needed it in about 7 months. And unfortunately, it was sitting in my garage in a state of low-charge for most of that time.
Well, my car battery died the other day, so I wanted to get this charger back in action. It was obviously out of charge, but when I plugged it in to charge, nothing happened. No lights come on, nothing happens when I press the "battery test" button, nothing. I charged it overnight and nothing seems to be happening at all.
It's barely been touched, so I'm guessing this is because I didn't do proper maintenance on it.
So I guess what I'm asking is whether the jumper is just ruined. Is there any way to tell if it's still viable? Or was it in a discharged state for so long that there's no hope for it?