Quote:
Originally Posted by Big Boy w/ Big Toys
Why no AGM?? Never heard that before. Especially Yellow tops are made to 100% discharge numerous times without issue.
I have been using Odessy batteries for years. These are true dry cell batteries. They have no vents like the Optima batteries. So there is zero off gassing to worry about which also means no battery corrosion. Also found that they store much better in real cold weather without a battery tender with little discharge.
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Blue tops are the deep cycle Optima batteries actually. Yellow tops are somewhere in between starting batteries and deep cycle batteries. If you're not starting engines there's no point in using Yellow top. Blue will outperform it by a country mile in deep cycle applications.
What magical chemical composition is the Odyssey? I'd be curious to know which physical law they break. Because there is no such thing as a truly dry cell AGM except in their marketing people's heads.
I'm mostly just tugging on your cape. They won't leak because they're AGM, but they're still lead-acid. They're just not as wet as a typical starting battery for a vehicle. Or even an Optima.
Odyssey are designed to hold a charge for a long period of time without maintenance top offs. It's a nice plus if you need that feature. They're not deep cycle and will last considerably more charge/discharge cycles if charged before they get below 60%.
Typical lifespan of a good middle of the road AGM not designed for deep cycle is 300+ cycles before they won't hold a full charge when charged when they fall to 60%. If they're regularly fully or close to fully discharged they won't last that long.
Many AGMs require different charge rates to maximize their lifespan. Few RV converters provide thee charge rates. Doesn't mean you can't buy or build something that does, it's just not the commonly used rate from most RV converters. Non-vented or "dry" AGMs can only charge so fast or they'll damage themselves internally.
Done a LOT of battery plants over the years for many things. It's common these days to get 10 years or more out of the *right* lead-acid batteries used in torturous environments like off-grid solar powered locations and massive current draw data center UPS systems.
I'm currently using a pair of high current UPS cast-offs (site certification says they have to be replaced every three years, which meant a truckload of great batteries in great shape for both my dad and myself many years ago) that are roughly rated at 75 aH and you can discharge them at incredibly high rates without damaging them. They're AGM internally but squared off and not spiral/circular like most automotive applications... And heavy as ****. Ha.
Mainly using them because I have them. Most folk head toward 6V deep cycle golf cart type batteries for RV use. I figure the vibration and charging "abuse" these will get will make them only last three-four years in pairs, but I have seven or eight more on a maintenance charger that correctly charges them for spares. They're all over ten years old and will still test fine on a load tester to rated amperage output.
Excessive heat, vibration, over-discharging beyond design spec, and over/too fast charging all kill lead acid batteries. All of which are readily available in the RV world!
Many converters these days are at least mutil-stage chargers designed for wet cell deep-cycle 12V batteries. Some three stage, some four. The staging is often "close enough" to the spec for AGM such that they'll behave well for a long time, but not all AGMs.