Are The AGM Worth 2X The price Of PB?

[stefano_ita]

Read here and there, and finally about to decide what to do for my house battery bank (rechared via solar and wind and a small 24 v dc genset, done with a lawnmover engine and a 24 v 100 amp alt.)

The question is in the title

Looking on different site i've found

12 v 200 ah PB ordinary battery, about 180-200 euro

12 v 200 ah AGM starting battery about 300 euro, also with tubolar plate.

12 v 200 ah AGM deep cycle for traction and/or solar use from 400 to 600.
(i guess the last one are the same as starting, just with differnt label, or am i wrong?)

I would need 8x battery for 24 v 800 ah, a bit bigger than needed, never disharge over 30-40%, charger all adapted for AGM caratheristics, full time liveaboard use.

Thanks all
Stefano

[a64pilot]

In fact I would tell you to avoid AGM batteries.
I have AGM and it is my understanding that they must be fully recharged frequently, and that is hard to do with your charge sources.
I think you would be better off with FLA electric vehicle batteries, Golf cart batteries is what we call them here in the states.
I believe that from what you say is your intended use, it's likely that AGM batteries may not last as long as FLA, and certainly not twice as long.

[Vasco]

NO! And they do need to be fully charged regularly. I found out the hard way.

[Stu Jackson]

No, IN MOST CASES but not all, they are not. You have to match the product to the anticipated use and charging systems.

Here's why:

AGM Battery Issues (from Maine Sail)
AGM Batteries - Making The Choice | SailboatOwners.com Forums

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries | SailboatOwners.com Forums


Only YOU can decide what's right for you and your application.

[exMaggieDrum]

I was a long time promoter of AGM batteries. I had excellent service from mine while a few years before I went cruising offshore and at anchor full time but I also kept them well charged. I have decided that they would be fine for most powerboaters, and sailboaters who have and use a genset and a large battery charger (large as with charge amps that are 40% of the Amp-Hours of the batteries). You could get by with less but you would have to charge them longer, much longer than most sailboaters want to run engines.

If you primarily stay in marinas with shorepower and a smaller charger, i.e. you keep the batteries topped off, then you would be OK with AGMs as well.

The benefit of AGMs is that they do not need as much constant attention for electrolyte levels (water) and so the locations can be in more out of the way areas. They also do not have to be mounted upright as do wet cells.

So you would be better off with wet flooded batteries. Note that most all batteries are lead acid - Pb - even the AGMs). What you definitely need are TRUE deep cycle batteries, not dual start/deep cycle, and not start batteries. There are only a few manufacturers who make those. The "golf cart" or "fork lift" batteries (usually sold as 6v so 4 to make 24v in series) are true deep cycle (if coming from a good manufacturer.

Could you get away with less than deep cycle? That depends on exactly how you intend to use your batteries as many sailors do not have true deep cycle and are happy. They are not offshore cruisers though who use their batteries to the max.

I also highly recommend you look at MaineSail's excellent website "Marine How To's". Look at his discussions on deep cycle batteries and charging.

[stefano_ita]

Thanks all for the answer

I'll live on the hook, pratiically never at marina, so 100% self sufficience.
The pack will be always keep equalized via victron battery equalizer, for sure 100% charge at least once a week (with 24 v dc genset), from what i read the standard PB battery will last about 6 years if very well cared and paying attention to them.

The pb i saw where completely sealed, no need to add water.

Saw long life, real agm, declared life 10-12 years 2v 200 ah 180 euro each...

Opzs 2 v 200 ah, declared 3500 cycle at 30% DOD... 140 euro each

no way, the old PB win, the only that could change would be for winston lifepoy4....but we are on another planet, and especially the missing of voltage regulator for alternator for lithium battery stop me, maybe 5 years with this one (1400 euro for 19kwh, useful 6, max 7kwh...)and if some about lithium will go on the market we could think about it..

[zboss]

Except firefly agm batteries...they do not suffer this problem.

[stefano_ita]

Originally Posted by zboss

Except firefly agm batteries...they do not suffer this problem.

Wich problem ? The AGM charging curve or the deep discharge?

[vtomanov]

Honestly speaking all this batteries are in the past : no point buying anything else then LiFePo4 this days I've put little bit more description here :

Equalizing Batterys - Cruisers & Sailing Forums

[reed1v]

We used 2volt cells purchased from naval salvage(submarines) that lasted over 18 years. Simple to maintain, huge capacities, and servicable in any port around the world. Of course each weighted 60 pounds. We had two banks so close to half ton of batteries. Like old farm batteries, the plates were huge. Just add distilled water, keep clean, and keep the contacts covered with a plastic spray. More wattage than most homes consume. The advantage of single 2 volt cells is that if one goes bad, easy to replace(assuming your a weight lifter).

Did i mention they are cheap to buy and can be infinity abused without impairing their ability to recover full charge.

[zboss]

Originally Posted by stefano_ita

Wich problem ? The AGM charging curve or the deep discharge?

Deep discharge AND charging curve. You can leave them in a discharged state for long periods of time, or only rarely bring them back to full, and they will regain their full capacity after a specific charger/discharge cycle specified in their manual.

This also means that you can run them between a discharged state and only 80% or 85% full - on a regular basis - and they will not suffer long term capacity loss.

[doublewide]

AGM are probably worth the extra cost for some people.
Remember, that if you switch from flooded lead-acid to AGM you need to change your charge algorithm. Flooded lead acid batteries charge at higher voltages than do the AGM batteries. AGM batteries bulk charge at 14.3 and float at 13.3 V. More than that overcharges them, boils off the water and they die. Your alternator and solar charge controllers are probably not able to regulate down to 13.3 V, so you also need to price in a new alternator with external regulator and a new solar controller. Worst case you may need a new inverter/charger, too. It's a bigger upgrade than you may realize.

[sy_gilana]

Based on the date codes on the batteries dumped in the recycling area in several boatyards.

NO.

[stefano_ita]

Originally Posted by reed1v

We used 2volt cells purchased from naval salvage(submarines) that lasted over 18 years. Simple to maintain, huge capacities, and servicable in any port around the world. Of course each weighted 60 pounds. We had two banks so close to half ton of batteries. Like old farm batteries, the plates were huge. Just add distilled water, keep clean, and keep the contacts covered with a plastic spray. More wattage than most homes consume. The advantage of single 2 volt cells is that if one goes bad, easy to replace(assuming your a weight lifter).

Did i mention they are cheap to buy and can be infinity abused without impairing their ability to recover full charge.

Thank you very much, this is interesting, i read also the


RyanEnergia - BATTERIE SOLARI - BATTERIA STAZIONARIA PIOMBO ACIDO OPZS - Batteria Opzs 2V


2 v 200 ah 135 euro, 15-20 years lifetime 3000 cycle to 50%...stated

It would be an investment just buy 12x battery to make a 24 v battery pack, for example 100 ah is 110 euro and a 1000ah is 425 euro, all in series and nothing else,

I looked for 2 v battery balancing system but nothing, any idea of brand?
Does it charge well with ordinary alternator regulator alright?
What about if completely full filled with acid, the boat rols and pitch? Will it leaks? (very very big problem a bilge full of acid)..Ok i get it in the middle of the boat...But it will always move. (and they are usefull as ballast)

With 12 x 600 ah cell i could get 14.4 kwh (vs 19.8 of the PB, but usable the same) for 3.000 euro (vs 1400euro for the PB)

[stefano_ita]

Originally Posted by doublewide

AGM are probably worth the extra cost for some people.
Remember, that if you switch from flooded lead-acid to AGM you need to change your charge algorithm. Flooded lead acid batteries charge at higher voltages than do the AGM batteries. AGM batteries bulk charge at 14.3 and float at 13.3 V. More than that overcharges them, boils off the water and they die. Your alternator and solar charge controllers are probably not able to regulate down to 13.3 V, so you also need to price in a new alternator with external regulator and a new solar controller. Worst case you may need a new inverter/charger, too. It's a bigger upgrade than you may realize.

Thanks, for sure i will look that solar-wind regolator will be also Agm compatible, while about alternator, maybe with a balmar regulator that can be setted to agm it can be done..the same for battery charger

I'm about to move to the winston...the only problem is the alternator regulator...

Just one big investment or new and new battery every 5 years (invironment's says no thanks)


What about rools? Maybe the best price-performance match

Rolls SERIE 5000 Banco Batterie 24 Volt 18,48 kWh C100


3200 cycles at 50% dod, does they works well if always keep between 70-85% state of charge?