LA Battery Report

[Trimaran Ken]

Originally Posted by a64pilot

So long as automobiles have a 12V battery, AGM will stick around, because quite often it’s the best car battery.
Cars batteries probably outsell well, just about any other battery.

Yes, my guess is that it will take about 5 years for car makers to start using some form of lithium and 10 years from now before they become standard.

However, there may be a problem with very cold temperatures (below -20 C) and lithium batteries that may prevent them from moving directly into cars. There are very few boats that need batteries to perform well in extremely low temperatures, so that this aspect will not effect us boat owners. I'm guessing that the car people are working on these drawbacks as we speak.

LA batteries of any type, do outperform LiFePO4 in engine starting ability, so some boats with heavy starting requirements, may want to keep LA for the starter set and LiFePO4 for the house set.

[Trimaran Ken]

Originally Posted by KTP

We bought AGM because our batteries are packed away in a low part of the boat and watering is what you do to plants.

Makes sense. Every application is slightly different. I don't expect to ever have to interact with my battery anytime in at least the next 10 years, likely 15 years if I'm alive that long.

[john61ct]

Originally Posted by Trimaran Ken

LA batteries of any type, do outperform LiFePO4 in engine starting ability

Codswallop

[john61ct]

And yes nitpicky I know, but AGM, all VRLA including GEL, and even cheap non deep-cycling SLA are all included within LA.

As is FLA.

LA just means a lead battery of any type.

[Adelie]

Originally Posted by bcboomer

Firefly, no need to hit 100%, no need to limit to 50%.
Plus all the advantages of AGM.

Fireflies aside I don't see significant advantages to AGMs for house loads while cruising.

Sealed battery. So are Gels and they have twice the life or more than AGMs for a modest increase in price.

High acceptance rate for fast charging. Only works if you are recharging from shore power or have a high output alternator. Even then it only shaves 15-30min from a 7hr process if you are starting from 50% SoC. If you are starting from say 75% SoC you will already be voltage limited and there will no improvement in charging time. If you don't have a high output alternator you still need to pony up for a somewhat smart regulator or you run the risk of overtaxing your regular alternator and frying it. And not being able to charge at a comparatively high rate will cut into the life expectancy of AGMs.

Low self-discharge rate. Not a problem if you have some sort of solar going when the boat is laid up.

High discharge capacity. If you need high discharge rates (approaching 1C or higher) you are talking about uses other than house loads.

Ability to operate in unusual attitudes. I wouldn't consider installing any part of my house bank on its side, its end or upside down.

All this presumes a sailboat with a moderate amount of solar panels installed and an interest in limiting engine time.


For specific things like propulsion AGMs are great and I will probably get one to run the trolling motor I use to push my dinghy around. Though I would prefer a Firefly for that.

[Exile]

Possibly the one & only advantage I see with AGMs is if your batteries are located directly under your berth. May or may not be a problem, but I'm a bit leery of the added gassing off. I also think terminals stay cleaner with a sealed battery, but that could be just anecdotal.

[a64pilot]

AGM’s are also available in a shorter battery than flooded, which is why I ended up with them, because I literally couldn’t fit flooded cells.
My next bank will most likely be Gel though, I still can’t figure out why they aren’t used far more than they are.
I think I want four 200ish AH 12V gels, but haven’t really begun the research yet.

[john61ct]

I agree too many default to AGM, and get poor value as a result.

But outside NA market conditions often favor LFP as the better alternative, in the US we're spoiled for lead choices.

Yes GEL **can** be very long lived, but their care requires more precision and adjustability than many owners want to bother with.

Sideways or difficult to reach locations aren't anyone's first choice but often required.

And high-amp loads like windlass or bow thrusters are often best included in a single larger House rather than going to 3 or 4 banks.

Finally even if the only reason is, "I can't be bothered watering and hang the extra cost per year", that is perfectly valid decision, not just a default out of ignorance.

Each use case has its priorities, every owner her preferences.