Gel Battery help please

this is a 2015 Gem E4
2 / 2018 Gell battery
individually checked them all
seems that #1 is bad

now for the question:
I know they are old but all the tests show that that all are above the CCA of 450 wich is factory.
should I just get one new battery to replace;ace the bad one if it buys me some more time.
I know everyone says replace them all at once.

Sure, you could give it a try.
It will buy you a bit of time.
It also looks like you might be needing to replace battery 2 shortly too.

What is the story on these batteries? Were they bought all at the same time, or were they mix/matched previously.

You should come back more often and check their balance. Make sure your charger is using the correct profile setting and that there are no stray loads on a cell or two (the lazy way of hooking up accessory lighting).

all bought at the same time, never mixed matched 2nd set from original deka gel #8G31
only a radio that was factory installed, and ride for fun motor. Thanks for the input

charger is on correct gel setting

Have you tried boosting up the low ones and see if they will keep up with the others?

(put a car charger on cell#1 for a day) Shut the car main switch off.

Still…5+ years on a set of Gels is nothing to complain about. That was back when lead was good quality. I don’t expect that out of today’s batteries.

How is this car is used?
Stored for seasonal use?
Stock/Timer/trickle/ charged? or charged and full shut down/put to sleep?

If the radio is connected to the first battery directly, it will prematurely kill that battery before the others. Radio should be wired thru the fuse box.