I have a car battery that wasn’t that old, but was just barely under the ideal operating specs so I replaced it with something a bit better. Is it possible to hold on to the battery to use for a jump if needed in the future? It was working just fine and I had no problems with it. Honestly I’m not entirely sure it needed replacing but going into winter I wanted to be safe rather than sorry.
A battery will discharge internally over time unless you keep it on a charger. If you have a fresh battery in your car, you probably won’t need a jump start. I would suggest that you give the battery to someone who needs it.
If you keep the battery charged it ought to work for your purpose of jump starts. But if you own a battery charger, you will use it to charge the dead battery in your car, right?
Wasn’t there a “core charge” for the new battery?