The NOCO 150 I had in my car for 18 months failed to help me start a friends car.
As discussed on this forum, they have a small parasitic drain that requires they be charged more often than other jump packs.
When I went to recharge it, it refused. NOCO replaced it for free.
That said, I have an alarm on my phone to remind me to charge my jump packs every two months.
Two months ago my wife called and said her car wouldn't start.
I told her to hook up the NOCO. Red to red, black to black. Turn the power on. Car started right up.
I also have two of the Antigravity X-10s. They hold their charge a LOT longer in storage.
But, as noted, they don't have the capacity of the NOCO 150.
I keep one in the trunk of each car in service. But this time of year they might be cold.
So I have been keeping the NOCO in the house.