12thgenusa, nothing at all wrong with basing assumptions. The key word is "base" you did it with a hydrometer. It's the folks that stare at a hydrometer like it was a six inch needle getting ready to stab their rear that get into trouble. Or folks who transact 1/100th the amount of kWh activity on their battery then crow "My Way Is The Best Way For Everyone" that lead people astray. "I got 60,000 miles out of a set of tires" trumps "I got ten years out of a set of tires" every time.
A hydrometer is used to set a baseline, check for sulfation, and sample electrolyte clarity. A person needn't carry one in a holster unless they're in the battery business.
If a person is fine going to the battery store every two years dumping a wad of Benjamin Franklin's on the counter then ignoring their batteries until next time that's OK too. But it's not the right thing to say to other people, "Oh I do my battery thing the right way. You should too".
INTELLIGENT battery maintenance is so easy it is a crime. But like the cartoon image of someone painting themselves into a corner, screwing it up is easy too. Just don't go around recommending other people do it too.
You manage your batteries correctly. Money stays in your wallet. What you wrote makes perfect sense. Managing a flooded lead acid battery solely with a meter makes about much sense as managing children by meter.
