New AGMs to replace lead acid?

[john61ct]

Originally Posted by Catmandu

I have not had the privilege of actually testing the FireFly batteries but from what I have read of those that have tested them they are preferred to AGM. The only advantage that AGM's seem to have is in those rare cases where the batteries must be mounted in some non-upright position.

I believe Firefly falls within AGM, just a unique chemistry. They are also fine on their side. The only advantages other AGM have is longer more widely proven track record, lower price per AH up front, and more readily available.

Originally Posted by Catmandu

As for the firefly's vs. the Trojans my back of the envelope calculations indicate that you get about 3x more energy per dollar out of the Trojans over the lifespan of the banks.

The conclusion I came to: When I head out for an extended round the world trip the extra expense for the firefly's might be worth it if they are able to operate as advertised in psoc. While cruising near the USA its hard to beat the Trojans.

Yes withstanding PSOC is IMO the real USP for Firefly, if you know you can get back to 100% full every cycle then no need to spend the extra money.

But some people just can't, and have the money to spend up front to save replacing a cheaper bank more often.

The higher CAR and occasional deeper cycling are also nice to have.

[john61ct]

Originally Posted by sailorman33

Firefly Oasis states in their literature that their battery is good for 3600 cycles at 50% discharge and 1000 cycles at 80% discharge.

Lifeline Agm states in their literature that their battery is good for 1000 cycles at 50% discharge and 500 cycles at 80% discharge.

It is true that the cycles on a Firefly Oasis batteries will be substantially reduced when discharged to 80% (3600 vs 1000).

It is also true that when comparing Oasis Firefly and Lifeline, Firefly will give 1000 cycles at 80% discharge and Lifeline will give 1000 cycles at 50% discharge.

A Firefly Oasis battery discharged to 80% will give as many cycles as a lifeline battery discharged to 50%.

Also, not casting specific aspersions here, but these lab stats can **only** be used to compare different product lines within a given manufacturer's.

They are **not** reliable enough to use to compare two different manufacturers' lines.

And real life conditions don't allow real-world results anywhere near those published from even the most honest vendor, even more so than solar panel output stats.

[rwells36]

I own 8 of them and I can promise you they charge rapidly, I've drawn them down as low as 30% soc then back to 100% multiple times. I'm very pleased.

[dhays]

Originally Posted by sailorman33

I have done some further research regarding discharging Firefly Oasis batteries down to 20% capacity.

Firefly Oasis states in their literature that their battery is good for 3600 cycles at 50% discharge and 1000 cycles at 80% discharge.

Lifeline Agm states in their literature that their battery is good for 1000 cycles at 50% discharge and 500 cycles at 80% discharge.

It is true that the cycles on a Firefly Oasis batteries will be substantially reduced when discharged to 80% (3600 vs 1000).

Another way to look at it...

If you discharge a Lifeline to 80% dod instead of 50% dod, you are cutting the number of cycles available by 50%.

If you discharge a Firefly to 80% dod instead of 50% dod, you are cutting the number of cycles available by 72%.

Which is hurt more by a very deep discharge?

Unless you don't have the room, can't carry the weight, or will rarely get your bank up to 100% SOC, I just don't think that the Firefly batteries win on a $/Ah basis yet. Particularly if you compare them to other good quality deep cycle AGM batteries. The batteries I just installed claim 1100 cycles at 50% and 700 cycles at 80% dod. Even more importantly, they will get 2,800 cycles at 20% dod which is where I will be most of the time.

[skipmac]

Originally Posted by deluxe68

Here was your quote.

"4. It was correctly noted above that you cannot have too large a charger (and it was incorrectly stated in a couple of posts above that you can, or that you should not exceed 33% or capacity in charging current). Batteries will accept what they're going to accept, given correct voltage regulation. It doesn't matter if you have a 20-amp charger or a 2,000-amp charger, if you regulate the voltage correctly the batteries will accept EXACTLY THE SAME AMOUNT OF CURRENT."

And that is exactly correct but perhaps you are reading it incorrectly. Of course different batteries will accept more or less charge depending on the battery chemistry, brand and a number of other variables. What Bill is saying is that a larger charger will not put more charge into a specific battery than that battery will accept. If a battery will accept 10 amps of charge current then connecting a 10 amp, 20, or or 100 amp charger will not change what the battery accepts as long as the chargers are properly regulated, IE charge voltage set correctly.

Consider this, a 12V light bulb will only draw so much current and make so much light when connected to a 12V source. Doesn't matter if that source is 8 AA batteries or a large,bank of 20 X 12V 8D batteries. Charging a battery will work the same way.

[StuM]

Originally Posted by skipmac

And that is exactly correct but perhaps you are reading it incorrectly. Of course different batteries will accept more or less charge depending on the battery chemistry, brand and a number of other variables. What Bill is saying is that a larger charger will not put more charge into a specific battery than that battery will accept. If a battery will accept 10 amps of charge current then connecting a 10 amp, 20, or or 100 amp charger will not change what the battery accepts as long as the chargers are properly regulated, IE charge voltage set correctly.

But that "properly regulated" is the key.

A battery that will accept 10 Amps of charge current at one input voltage will accept more current at a higher voltage. That's the whole point of "constant current charging" in the bulk phase.

Consider this, a 12V light bulb will only draw so much current and make so much light when connected to a 12V source. Doesn't matter if that source is 8 AA batteries or a large,bank of 20 X 12V 8D batteries. Charging a battery will work the same way.

But hook that same light bulb up to 24 V. What will happen and why?

[john61ct]

All discussion of varying current sources and charge acceptance has to assume the source will competently cap Volts at the configured setpoint.

If it doesn't, IMO it should be taken out of service immediately.

[skipmac]

Originally Posted by StuM

But that "properly regulated" is the key.

A battery that will accept 10 Amps of charge current at one input voltage will accept more current at a higher voltage. That's the whole point of "constant current charging" in the bulk phase.

Of course this is correct. Electricity 101, but that isn't the issue. Bill's point was that having a larger charger will not overcharge the batteries per se. The point is, two chargers, if set at the same charge voltage will only charge the battery at the rate it will accept, even if one has a capacity of 100 amps and the other 20 amps. However, if the battery will accept 50 amps then obviously a 100 amp charger will bulk charge the battery faster than the 20 amp charger. So other than cost and possibly installation of the larger unit, there's no downside to a larger charger. In addition to higher output a larger charger, depending on the system, state of charge, etc will usually be running at a lower percentage of it's rated output so run cooler and last longer.

Originally Posted by StuM

But hook that same light bulb up to 24 V. What will happen and why?

What will happen is you will demonstrate Ohm's law in the form of I=V/R. In simple terms, V doubles then I will double, the R will probably make a very bright light for a very short time and then produce smoke.

[ranger58sb]

Originally Posted by sailorman33

I have done some further research regarding discharging Firefly Oasis batteries down to 20% capacity.

Firefly Oasis states in their literature that their battery is good for 3600 cycles at 50% discharge and 1000 cycles at 80% discharge.

Lifeline Agm states in their literature that their battery is good for 1000 cycles at 50% discharge and 500 cycles at 80% discharge.

It is true that the cycles on a Firefly Oasis batteries will be substantially reduced when discharged to 80% (3600 vs 1000).

It is also true that when comparing Oasis Firefly and Lifeline, Firefly will give 1000 cycles at 80% discharge and Lifeline will give 1000 cycles at 50% discharge.

A Firefly Oasis battery discharged to 80% will give as many cycles as a lifeline battery discharged to 50%.

Because Firefly Oasis has a much larger useable capacity the battery bank does not need to be as large. Cost saving and weight saving.

When on anchor you are probably only able to charge your battery to 85%. With a discharge down to 50% you have a useable capacity of 35%. With a discharge down to 20% you have a useable capacity of 60%

The ability to discharge down to 20% will almost double your useable capacity when you are only charging to 85% (from 35% to 60%).

If this math is correct... (??)

Looks like Trojan T-105s are least expensive (of these particular comparisons) then Firefly Oasis discharged only to 50%, then Lifeline to 50%, then Oasis to 80%, then Lifeline to 80%...

I chose the 3/G31 vs. 4/GC2 comparison because that's our real-world situation: we had space for 1x8D, 3xG31s, or 4xGC2s.

Trojan and Firefly prices are a quick WAG from the first Internet return I found, prolly doesn't include transportation, tax, etc. Lifeline prices were what I paid last month. I included Trojan T-105s here simply because they're a popular flooded lead-acid solution, presumably not too dissimilar from other decent 6V FLA brands.

Small differences in bank weight don't seem particularly significant, to me.

No guarantees the math is correct.



-Chris

[john61ct]

Need to add Sam's GCs at under $180 the pair.

[ranger58sb]

Originally Posted by john61ct

Need to add Sam's GCs at under $180 the pair.

Would likely be even less expensive than the Trojan option, but would depend on predicted cycle life... if you tell me that, and give me capacities and weights, I'll remake/repost the chart. (Are they East Penns of some sort?)

I thought about including Odyssey, too, since that's what we've had good success with... but since that part of the thread was focusing on Firefly and Lifeline, I just held it to that... and threw in the T-105s to stir the pot.

But I was mostly just intending the chart -- just a simple spreadsheet -- to simply illustrate a way folks could do comparisons relevant to their specific situation -- how many batteries, space issues, required capacity, etc. Assuming the math is correct and the comparisons are logical/appropriate.

Of course all that doesn't take into account that real-world "cycle life" -- relative to manufacturers' published specs -- is kind of a crap shoot. Doesn't take into account other battery issues, either, like servicing wet batteries, reduced off-gassing and self-discharge for AGMs, recharging capability, etc. mostly since those don't lend themselves toward quantification.

-Chris

[john61ct]

Originally Posted by ranger42c

Would likely be even less expensive than the Trojan option, but would depend on predicted cycle life... if you tell me that, and give me capacities and weights, I'll remake/repost the chart. (Are they East Penns of some sort?)

Yes Duracell GC2 sold at Sam's / B+ is made by East Penn, the Deka GC-10 and the EGC2 is a Deka GC-15.

And I agree that calculating cycles per dollar is too pie in the sky, rewards the company that lets marketing puff the specs up, those cycles vs DoD charts are only good for comparing lines within one mfg.

Just $ per AH (maybe cents/kWh better mixing 6V & 12V) is enough, it's pretty clear with these trusted mfg, spending more does get you better longevity, just can't be quantified without say Practical Sailor paying Maine Sail to do a Consumer Reports style study over many years.

Also AGM should be separated from FLA, include Odyssey and Northstar as well as Concorde.

Additional FLA should include Rolls/Surette, US Battery, Superior, Crown.

Make it a Google Sheet live, share editing access with those adding lines, would turn into a good community project.

[john61ct]

I couldn't find my source for these snippets:

s550 Rolls batteries will produce 428ah (in series) at 12v and cost about $680 for the pair. = $1.59/ah/3000 cycles = $0.00053 /ah/cycle

Sam's Club Energizer GC-2 deep cycle golf cart batteries will produce 208ah and cost $169 (locally) for the pair. = $0.81/ah/700 cycles = $0.0012 /ah/cycle

-----
just for examples about units, as I said before if these calcs are done there, the caveat needs to be spelled out in big red letters

same with local costs vs shipping charges, that alone blows things right up on a small/cheaper bank

[ranger58sb]

Originally Posted by john61ct

Yes Duracell GC2 sold at Sam's / B+ is made by East Penn, the Deka GC-10 and the EGC2 is a Deka GC-15.

And I agree that calculating cycles per dollar is too pie in the sky, rewards the company that lets marketing puff the specs up, those cycles vs DoD charts are only good for comparing lines within one mfg.

Just $ per AH (maybe cents/kWh better mixing 6V & 12V) is enough, it's pretty clear with these trusted mfg, spending more does get you better longevity, just can't be quantified without say Practical Sailor paying Maine Sail to do a Consumer Reports style study over many years.

Also AGM should be separated from FLA, include Odyssey and Northstar as well as Concorde.

Additional FLA should include Rolls/Surette, US Battery, Superior, Crown.

Make it a Google Sheet live, share editing access with those adding lines, would turn into a good community project.

Originally Posted by john61ct

I couldn't find my source for these snippets:

s550 Rolls batteries will produce 428ah (in series) at 12v and cost about $680 for the pair. = $1.59/ah/3000 cycles = $0.00053 /ah/cycle

Sam's Club Energizer GC-2 deep cycle golf cart batteries will produce 208ah and cost $169 (locally) for the pair. = $0.81/ah/700 cycles = $0.0012 /ah/cycle

-----
just for examples about units, as I said before if these calcs are done there, the caveat needs to be spelled out in big red letters

same with local costs vs shipping charges, that alone blows things right up on a small/cheaper bank

Tried to capture the part about Energisers, at least how I interpreted your note... but didn't get the same results you got, so maybe I misunderstood or our calcs are different. Or maybe my math is wrong. Still seems favorable, though...

I also added the Odyssey batteries we've had installed all this time, but only using they're typical spec of 400 cycles/80% DoD (haven't found their spec for 50% DoD). Our oldest bank of 3x that we just replaced was from a March 2006 installation... Or other large bank of 3x is from Sept(-ish) 2009, and I'm thinking to eventually replace that one with 3x Firefly Oasis batteries when the time comes. Pretty sure I don't have room for GC2s there, anyway. Still have to do some comparisons of Firefly cranking amps and minimum engine requirements, though, but looks good so far.



I didn't try to include the Rolls batteries, simply 'cause they don't fit our use case; too tall.

And doing much more is maybe a project for somebody who knows how to spell Google Sheets... and even then, the number of potential use cases are so varied that each particular installation would likely need it's own calcs.

The caveats and the intangibles seem like the biggest deal to me. As you say, "marketing math" doesn't necessarily reflect reality, and as RC (Maine Sail) has said, each lab tests differently so predicted cycles from various makers maybe aren't all on the same sheet of music in the first place. And then how would one measure intangibles like reduced servicing requirements or reduced off-gassing, alternative installation positions, etc.?

Still, some attempt to quantity using whatever info is available seems a slightly better approach then just buying the green ones, or the blue ones, or the pretty orange ones...

-Chris

[john61ct]

No need to even think about cranking CCA ratings once you get up to hundreds of AH.