16 Lifeline GPL-4C Batteries, replace 1 or all?

,punk

You have to ask the question;
Flooded batteries usually last 2 to 5 years, AGMs are suppose to last longer, say 4 to 6+ years. But your in a boat, anything can happen is this hard environment,
,, So, Do you feel lucky???

If I had the bux, swap them all is smarter, and , go back to flooded wet cells. In my years on boats, AGMs have not proved them selves for the money, IMO..
I love to sell them when specified, but with flooded (8) 8 volt 19", (2) 12 volt 8Ds, (4) 12 volt 31s on our ole Bert on over 4-5 (some over 7) year cycle per battery I can not see AGMs for us. I check all banks about twice a year. pour in them all about 2 gallons of distilled water. Clean some connections and wash the battery box wells. My batteries are happy. Yep, I feel lucky..

Others may argue, but it's your bux.
,rc

Lifelines are supposed to go a long time, and have a 7 year warranty don't they? HOwever if one died, I'd be inclined to replace all of them, or at the very least the entire bank that the bad battery was on. As for someone saying AGM's go longer than lead acid, I have not seen that by much on most brands. I've replaced many AGMs that are 3 years old. Good gel batteries, on the other hand, I've seen go 7-10+ years many times.

Same here, I haven't seen any significant difference in longevity between AGM and LA. AGM have other benefits but in many cases LA are a better option

One out of 16? 1 d be tempted to replace just the bad one if all the others are good. If you get another year out of the bank it s worth the gamble of one battery Make sure the other 15 are good, no sign of bulging, staying cool, etc. also, take into consideration not just the age but the number of cycles and whether they have been deeply discharged one time too many.