Just put the new battery in and turn the other one in as core. Batteries discharge in storage and the damage done during self discharge greatly reduces their usable life...if you put it on a float charger it will keep that from happening , but the batteries life cycle started when it was filled with solution. it will be done in X years based on it's construction..improper storage ...that includes not properly mounted in a car, but vibrating around in the vehicle along with self discharging...only shortens it's life.
I've done battery testing for gates when they developed the spiral battery...and later Johnson Controls / Ford engineering...Worked with Optima rep on charging technic for self discharged/ sulfaded batteries...use it or loose it, we exchanged all batteries not used in one month with fresh from the distributor
The old battery's 5 years or older? Put the new one in.
You might be stranded somewhere unless you keep the new battery and tools in the trunk. And it might die when the weather is freezing or rainy.
I got a cyber Monday deal on a battery and Im concerned my current one may go out on me. However, it hasn't yet.
There is an $18 core charge but I hate to give them my old battery if its still good.
Can I hold off on using the new one until my old one quits ?
And if so, can I return the core with receipt months from now to get my $18 back ?
Last winter, after not going anywhere for a week or two, it ALMOST didn't start on me.
And once at a gas station, I must have left my lights on and it wouldn't crank, it wouldn't crank with my old jumpbox either but I did get someone else to jump me off and its been fine ever since.
My jump box is about 9 years old and it shows nearly fully charged but it wouldn't work for me when I needed it.
Of course, my battery is a side post too.
My plan was to sit the new battery on a shelf and then if my car wont crank, install the new one so I wont have to call anyone and I wont be stranded.
Also, is there any way to check my jumpbox to tell if its still good ?
Thanks
