Originally Posted by gettinthere
My reading over the years has always shown wet cells last longer than agm's. Almost twice as long. I've never, before this thread, read of agms lasting 10 years.
The trick to making AGM's last for a long time is to never over-discharge them and never over-charge them. Their charge and discharge cycles must be carefully controlled.
Since the AGM's are sealed, you can't add water
if you overcharge them. They vent, and that's it. they're done.
If you over-discharge them, they shed active material from their matrices and they're done. The spiral-wound matrix is a little more fragile than a conventional plate, wet-cell battery.
As for checking the electrolyte in wet-cell batteries, if you buy a modern, Schumaker battery charger
or battery tender
, they will shut off when the battery is fully charged, or go into "standby", preventing an over-charge that boils off the electrolyte. This greatly reduces the need to check the levels, and almost entirely eliminates the need to add water
because it hardly ever boils away.
lovers make it sound like it has to be checked every other day or something. In a sailboat application, the only advantage to an AGM battery is no mess in a casualty like extreme heeling or capsizing.
AGM's have other excellent properties like being able to discharge high amounts of current
very quickly, which is great for racing electric
vehicles, or heavy starting applications, but that doesn't often apply to sailboats.