AGMs are not solid state, they have the liquid acid absorbed in fiberglass mat. Solid state batteries are something completely different and way out at the bleeding edge of development.

AGMs may initially charge at 3x the rate of FLAs when discharged to 50% but quickly taper to the point where they are charging at the same rate. From the point that each reaches absorption voltage until the end of charging they take pretty much the same amount of time, about 4-5hr. With high amperage charging it is possible to shave 20-45min off of a 6-7hr charging cycle.

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Num Me Vexo?
For all of your celestial navigation questions: https://navlist.net/
A house is but a boat so poorly built and so firmly run aground no one would think to try and refloat it.

I purchased a pair Optima blue top AGM batteries in 2005; one lasted ten years and the other was still going fine when I replaced it after eleven years.

We've had four Trojan Group 24 AGM batteries for the past 10 years, two for starting (originally a Nissan LD-28, now a Beta 85) and two for the house. They're great; for me the primary attraction was that the space for house batteries on our 1985 27' Albin Family Cruiser is inaccessible for checking electrolyte on a regular basis. The frosting on this cake has been their 10-year life, so far.

AGM batteries were great when they were originally introduced, but with the prevalence of Lithium based batteries today, their time has passed. Already it is less expensive to use automotive based LiPo batteries instead of lead acid.

The main headache is that it is still in the DIY phase and people who dont have the nerve and skills for that have to resort to more expensive OEM solutions like Battle Born. I have personally bought my last lead acid batteries, the next system will be based on hardware out of one of the more common EV's and will be lighter, more powerful and much more responsive to charging that any lead acid system I have ever had.

The youtube channel "DIY Solar Power with Will Prowse" is an excellent resource. If it is something you can buy he has probably tested it and torn it down to see whats inside. He probably has a long term review on it too, there does seem to be a lot of stuff that is badly put together even if the components are quality. Well worth a look.

It may be an outlier but I bought one of those expensive AGM starting batteries in 1995 and it is still going strong.

Maintenance free, sealed and it just works.

My AGM deep cycle, not so much. After about 5 years in service, they just seem to kill themselves. It is always a case of sudden death.

AGM makes sense in 1 scenario, being the need for high charge rates, if you use a generator or engine with high output alternator to charge quickly. In that case AGMs will reduce engine run time (as would Lithium, but that's another ball of wax).


If you charge with solar, ie. a longer slower charge, then there's no better bang for the buck than FLA. Combining AGM with solar charging is just throwing money in the drink.

You need to select a battery chemistry that is best suited to the intended use. Then you need to provide the proper maintenance to maximize the battery life.

AGM are not the most cost effective for every use. I would not pay the premium for AGM use on lawn equipment or road vehicles...I can't speak to cell towers standby power cabinets.

That said I replaced my two West Marine (WM) 8D GEL house batteries on my boat in 2019 and they were 15 years old...I moor my boat out 24/7/365 without dock power. YES, I replaced them with another pair of WM GELs, older technology but (if as reliable as the old ones) they will outlive me. I keep them charged with 4x140W (560w) solar panels, a pair of Blue Sky Energy Boost 2512iX-HV charge controllers, Balmar MC-614-H Multi-Stage Regulator, multi-stage smart charger when at the docks, Xantrex LinkPRO Battery Monitor, and temperature sensors on every piece of equipment that needs it to maximize performance and longevity. Lastly, charging voltages have been set exactly as required by the manufacturer.

There is no "install it and forget it" with batteries.

~ ~ _/) ~ ~ MJH

just a marketing myth that only applies to a small portion of the SOC and only care to charge to 80%, in which case your fancy AGM will die the slow PSOC death

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Don't ask a bunch of unknown forum people if it is OK to do something on YOUR boat. It is your boat, do what you want!

Skylark had three Optima Yellow Top Series 31s for the house bank that lasted 11 years and two for the engine/windlass that are approaching 15 years.

I recently replaced the house bank with Full River AGMs that had good reviews and are priced similarly to Optimas.

The house bank had flattened three times over the years and I was concerned about the batteries becoming sulfated. I used a BatteryMinder pulsating charger and I believe that really allowed my house bank to last so long.

The engine/windlass bank never went flat and perhaps that's why they are lasting longer.

Skylark spends most of her time connected to shorepower, but every summer for 6-8 weeks, she charges by engine and SuperWind.

Examples and links please.
Price us up on 800ah@12v
Landed in Australia.

years(decades) ago we refitted in Seattle before returning to Juneau Ak. I was offered to AGM batteries that were used taken out of a vessel headed out for a long ocean cruise. I purchase then and I recall they lasted well over 5 years. So I am satisfied with Lifeline AGM

It is less expensive to use marine LiFePo4 batteries than any other battery technology when you look at AH over lifespan.

The issue with any lead acid battery - Fla, Agm, or gel - is that they need to be fully charged very often. This can be hard to do on a sailboat.
Agm batteries are fussier than Fla batteries in this respect.

Other than not needing the addition of water I cannot see a great advantage to Agm batteries. More expensive than Fla with their life no longer than Fla if both are treated well.

Has there been any actual proof yet?
Or is it what the marketing dept and brochures has told you?

No-one can help you with shipping and I dont know your sources. So here goes
https://bigbattery.com/products/48v-plbr/
48V PLBR - NMC - 186Ah - 9.6kWh $3700

https://bigbattery.com/products/48v-hawk-kit-of-2/
Kit 48V HAWK - LifePO4 - 170Ah - 8.8kWh $3400

https://bigbattery.com/products/12v-...70ah-2-176kwh/
12V OWL - LifePO4 -170Ah - 2.176kWh $979 each (discount on multiples) 4x gets to 8.5kWh

https://hsrmotors.com/products/battery_modules
Tesla battery modules
22V Nominal, 5.2kWh
27x12x3" in size
58lb per module
cost each $1390 + shipping



Usable capacity with any of those batteries would be far superior to an lead acid system since you can go much deeper than 50% discharge if you need.

As I have reported before, 2 of my 3 AGMs cracked and leaked acid. These batteries were about 6 years old and never gave good service. In the tropical heat, the 8D AGM cases cracked while in storage during the hurricane season. In my experience it is a myth about being safe even upside down.

Many report early failure of AGMs but that is likely a problem understanding the proper voltages needed to maintain them.

I went back to a bank of 8 six-volt batteries wired in series-parallel. The bank of Trojans before served for 12 years and this new bank of generic golf-cart type batteries is 3 years old.