Why are so many in Love with AGM's

[Lost Horizons]

Originally Posted by Adelie

For deep cycle use cost favors traction or golfcart FLA over AGM by at least 2:1.

Cost also favors walking over driving, eating rice instead of steaks, having one pair of shoes, living in a trailer park,... the list could be very long.

I like the ability to discharge batteries to 20% of their capacity, did it regularly with the previous boat. The charger was only a small 20A one working a 200 A*h battery bank. Frequently undercharged them during long trips - the boat had standard 70 A alternator with no other charging means underway, so I would regularly run the engine a couple of times a day for about 30 minutes at a time. Had that boat for 5.5 years, sold it with fully functional original batteries. So I get to laugh when someone is promoting a century old technology over a modern one using unsubstantiated scare tactics.

Recently checked the batteries (AGM) in the present boat. With unplugged charger they showed 12.8 V after one month of sitting with no use. Good enough for me. If I keep this boat longer than the original batteries last, will replace them with the same type or perhaps with Fireflies or whatever new technology is available then.

[Simi 60]

Originally Posted by Adelie

For deep cycle use cost favors traction or golfcart FLA over AGM by at least 2:1.

.

In some parts of the world
Others not.
Here a T105 is about $300 x 2 = $600
to equal my 220ah @ 12v AGM that cost $375 each

[sailinglegend]

Originally Posted by flyingfin

I have had nothing but problems with AGM batteries....

My summary of AGMs - after my first bank lasted 14 years as a liveaboard:

Advantages

Not all AGMs are created equal, so any advantages may not apply to all brands

AGMs have a higher charge efficiency
And they can take a higher charge current than FLAs - so may charge 20% quicker
Some advertise an 80% DoD - but 50% will give a longer lifecycle
They don’t spill or gas and so don’t corrode the battery terminals
Because they don’t spill or leak acid they don’t need a battery box
Because they don’t gas they can be installed in living accommodation
They can be set at any angle - great for saving space
They may be up to 10% smaller than other FLAs.
They do not freeze
They have a self discharge of about 1% per month - FLAs can be up to 10%
Good as a bowthruster battery as they maintain their voltage under heavy loads
Can be used as starter batteries
High impact resistance - falling of a 3 metre wave
No maintenance - no electrolyte topping up
Firefly claim they don’t need to be fully charged every cycle

Disadvantages:
They are more expensive than FLAs
Because they accept high currents all charging sources may need an upgrade
There is some evidence they need fully charging more regularly than FLAs
Some brands are not suitable for ‘marine use’

[sailorboy1]

People like AGMs when they accept the marketing hype and luck out as it having worked out for them. To my mind their only advantages are you don't have to water them and they don't spill. Everything else is just marketing hype!

[sailinglegend]

Originally Posted by sailorboy1

Everything else is just marketing hype!

Certainly clueless!!!!

________________________
Ignorance is what you know don't it's what you think you know that is incorrect.

[sailorboy1]

Originally Posted by sailinglegend

Certainly clueless!!!!

________________________
Ignorance is what you know don't it's what you think you know that is incorrect.

MY guess is that was an insult. But for every "I got 12 years out of my AGMs" like you I can find a dozen cruisers who got less than 6. In fact this thread is basically about AGMs not living up to the hype. I would refute your claims, but why would I care what batteries other people want?

[manitu]

Originally Posted by sailorboy1

MY guess is that was an insult. But for every "I got 12 years out of my AGMs" like you I can find a dozen cruisers who got less than 6. In fact this thread is basically about AGMs not living up to the hype. I would refute your claims, but why would I care what batteries other people want?

I guess you don't see that you are insulting everyone diligent enough to research battery chemistry to make a educated choice which suits their usage and charging regime.

And yes . Absolutely clueless.

.manitu

[DefinitelyMe]

To answer the OP question, in my case:

- I live on an island. AGM's can be shipped in as non-hazardous cargo. The alternative is to buy locally and risk that they've been sitting on the shelves and sulphated.

- I don't have access to the top of my batteries without removing them

- I've had good experiences with them.

Currently on my second set of Lifeline 8D's. The first set were still performing brilliantly after ten years but I was heading to the Pacific so replaced them before they failed. Second set is now 6 years old and doing fine.

Honestly I probably would get wet cells if it weren't for my first two points, for price reasons.

[rslifkin]

Originally Posted by sailorboy1

People like AGMs when they accept the marketing hype and luck out as it having worked out for them. To my mind their only advantages are you don't have to water them and they don't spill. Everything else is just marketing hype!

AGMs also usually handle high amp discharges a little better than FLA and have a little higher charge acceptance rate (until they get up to 80% or so). But those aren't huge benefits in most cases. In my case, I use them because of the lack of outgassing and spillage concerns, as it would be a bit of a paint to make a suitable containment tray for FLAs where my house batteries sit. And I'd have to add ventilation, as there's only a little bit in that area.

[Rubicon King]

Good OP post....No idea the love for AGM. That said, I've got 8 FLA house batteries, another for Gen Set, Another for Engine, and another for Windlass, so 11 total. All work great, but I don't pull more than 30% off at any given time. I suspect it depends on your mission and how deep you pull the charge down, and how often. "If all you need is a Chevy, why buy a Tesla." I do realize the weight that adds to my 45', but it works for me.

[sailorboy1]

Originally Posted by manitu

I guess you don't see that you are insulting everyone diligent enough to research battery chemistry to make a educated choice which suits their usage and charging regime.

And yes . Absolutely clueless.

.manitu

I am OK with that. If you really did your research and came up some reason for spending more money on AGMs that wasn't about watering or spillage.

So not clueless, just too much NOT clueless.

btw - I have AGM batteries, but they are FirefFly batteries and a different animal

[Pete7]

Originally Posted by Rubicon King

Good OP post....No idea the love for AGM.

Me too. I was rather shocked to see Paul and Cheryl on Sailing Distant Shores ripping out a huge AGM battery bank on their newish yacht. It didn't last more than 2 years despite having thousands of pounds worth of Nigel Calder's Intergel charging system fitted a while back,

Having spent a huge amount of time over the winter reading and thinking about lithium I am now going for ....... Trojans T125, even if it means building a new battery box elsewhere on the boat.

Pete

[Group9]

We have some that are eight years old and still work great. I don't think I ever had a set of flooded batteries that lasted that long.

[tarian]

AGMs are as stated, lead acid in a solid state, all the precautions as lead acid, they are spull proof , and crack proof, they willl charge 3 x faster than standard lead acid
, and may need a different charge cycle to your dodgy old alternors or charge controllers,
So before fitting agms check your charging regime and alter were possible
AGMs are a great battery and sit below lithium as battery of choice in my opinion, but as they say you fet what you buy , so a quality AGm from a good company will last many years, ofc if you look after it

[friz]

Originally Posted by flyingfin

I have had nothing but problems with AGM batteries, from early failure after 18 months in lawn equipment, failure after 24 months in road vehicles (seems the batteries have insider knowledge of the warranty expiration date), to full blown melt-down and fire at cell tower standy power cabinets. Never had theses issues with lead-acid batteries. Is it because the AGM's are sealed and cannot gas-off?

I believe AGMs can be mounted on their side. This is a great feature when blo-boating as you spend 50% of the time walking on the bulk head underway.https://www.cruisersforum.com/forums...es/biggrin.gif