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Old 29-08-2019, 08:02   #1
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Firefly Oasis : 2 years old and dead

Hi,
two years ago I Installed 4 xAGM firefly G31 (4 x 116AH @12V) on our boat. We live aboard and have been cruising in the Med, through the Atlantic and Caribeean.
When I first received them, they had been leaking during shipment and had faulty valves that I had to change once sent from India.
The first capacity test only yielded 75% of rated capacity. After a year of service, the capacity test yielded 50% of rated capacity and we found out that one battery was bad. It got replaced under warranty. I was asked by the head of engineering at Firefly to revive the bank by equalizing them (which we are not supposed to, but...) It worked to some extant. One year later, bank capacity is below 50%, and Firefly has accepted to replace the three other batteries.
I have 350W of solar (yielding max of 1.7kWh /day), with a Victron MPPT controller, a Balmar AT200 and a 614 external regulator. We are barely at the dock, but when we are, I have a programable Victron Multiplus Compact Inverter/charger 70A.
I have followed all Firedly recommendation as far as settings.

So... Have you experienced such longevity issues with these batteries? what is your experience? do you follow the monthly maintenance/restoration process?
I m heading to the Pacific after moving up north the the Sea of Cortez, but would like to get know if I should switch to lithium (Trojan Trillium) before we go to the South Pacific.

All inputs are welcome. thank you.
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Old 29-08-2019, 08:48   #2
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Re: Firefly Oasis : 2 years old and dead

We just installed 5x G31 firefly batteries, so I can't comment on longevity yet. But I can say that we chose them because nearly all reviews I've read are glowing. All I can say is that its possible that initial damage (leaking) had something to do with their premature failure.
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Old 29-08-2019, 10:14   #3
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Re: Firefly Oasis : 2 years old and dead

Would you please guide me towards these glowing field experience feedbacks? I can't seem to find much about Firedly despite my researches on the net.
Thanks
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Old 29-08-2019, 10:27   #4
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Re: Firefly Oasis : 2 years old and dead

We have two firefly oasis batteries, and are on our second year with them, we have had no issues whatsoever thus far. We are a full time live aboard couple. It does sounds like the batteries were damaged before you took ownership of them. I have only heard good things about them outside of your experience. Hopefully the new batteries will live up to expectations.

Fair winds,
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Old 29-08-2019, 10:50   #5
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Re: Firefly Oasis : 2 years old and dead

I just purchased 6 G31 firefly and shipped them to the boat. Id had enough of Chinese AGMS that lasted on a few seasons.

I'll be keen to see how they do. The cost of the FF and shipping wasn't much more than purchasing good AGMS in south America.

If I had been in a first world country and planned to keep the boat more than another season or two I would have gone lithium, more than likely Victron as I have a full Victorn system.
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Old 29-08-2019, 11:47   #6
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Re: Firefly Oasis : 2 years old and dead

A thread called “my attempt to murder my firefly batteries “
I believe that was the thread title, under electronic, batteries forum .
Hope that helps. Also look at Maine sail’s “ marine how to” site he has good info there.

Fair winds,
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Old 29-08-2019, 12:58   #7
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Re: Firefly Oasis : 2 years old and dead

I've got three banks installed over two years, no capacity losses at all so far, but they were perfect at install and been well coddled.

Do the capacity restore only after unavoidable PSOC, but don't wait, soon as plentiful well-regulated power becomes available.

Do not go below 50% unless required, infrequent.

Expecting 5-7 years before hitting SoH 70-75% EoL
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Old 30-08-2019, 09:53   #8
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Re: Firefly Oasis : 2 years old and dead

What you have is a fragile battery that is not ideal for deep cycle (despite all the hype. AGM is built with minimal electrolyte so any leak or loss of water is likely to have immediately written off the battery with no possibility of repair.

The (potential) advantage of Fireflies is that you can discharge to a lower SOC therefore giving more usable power but less reserve. A standard flooded cell is also capable of discharging to 20% but if done regularly will have a shorter service life than the firefly (but often not a lower lifetime cost)
So 3 110 fireflies =330ah total; 215ah daily usable cycle capacity with 3-5 year life appox $2100 ($4-6000 over 10yrs)

4 6v FLA L16 = 860a/h total. 215a/h daily cycle from 85% SOC gives the same daily capacity but only discharges to 61% At these levels you should get 10yrs+ life and the cost is $1300 so lifetime cost is close to 1/4 than the fireflies. The bonus is that you have that 61% available as a reserve if occasionally you have a high demand or poor charging.
As with all batteries the key to long life is not DOD but getting them FULLY charged at least 1 month preferably weekly. Any discharge not returned withing a month is likely lost for good and the idea that you can continuously cycle batteries only recharging to 85% DOD will rapidly kill any battery
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Old 30-08-2019, 10:19   #9
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Re: Firefly Oasis : 2 years old and dead

Quote:
Originally Posted by FredVeroMakani View Post
do you follow the monthly maintenance/restoration process?
.
Im not seeing anyone answer this question.... I dont think.
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Old 30-08-2019, 11:19   #10
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Re: Firefly Oasis : 2 years old and dead

Quote:
Originally Posted by roland stockham View Post
What you have is a fragile battery that is not ideal for deep cycle (despite all the hype. AGM is built with minimal electrolyte so any leak or loss of water is likely to have immediately written off the battery with no possibility of repair.

The (potential) advantage of Fireflies is that you can discharge to a lower SOC therefore giving more usable power but less reserve. A standard flooded cell is also capable of discharging to 20% but if done regularly will have a shorter service life than the firefly (but often not a lower lifetime cost)
So 3 110 fireflies =330ah total; 215ah daily usable cycle capacity with 3-5 year life appox $2100 ($4-6000 over 10yrs)

4 6v FLA L16 = 860a/h total. 215a/h daily cycle from 85% SOC gives the same daily capacity but only discharges to 61% At these levels you should get 10yrs+ life and the cost is $1300 so lifetime cost is close to 1/4 than the fireflies. The bonus is that you have that 61% available as a reserve if occasionally you have a high demand or poor charging.
As with all batteries the key to long life is not DOD but getting them FULLY charged at least 1 month preferably weekly. Any discharge not returned withing a month is likely lost for good and the idea that you can continuously cycle batteries only recharging to 85% DOD will rapidly kill any battery
Well I guess next time I will go lithium. All my chargers are capable so I will not hesitate.
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Old 30-08-2019, 11:33   #11
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Re: Firefly Oasis : 2 years old and dead

Quote:
Originally Posted by roland stockham View Post
What you have is a fragile battery that is not ideal for deep cycle (despite all the hype. AGM is built with minimal electrolyte so any leak or loss of water is likely to have immediately written off the battery with no possibility of repair.

The (potential) advantage of Fireflies is that you can discharge to a lower SOC therefore giving more usable power but less reserve. A standard flooded cell is also capable of discharging to 20% but if done regularly will have a shorter service life than the firefly (but often not a lower lifetime cost)
So 3 110 fireflies =330ah total; 215ah daily usable cycle capacity with 3-5 year life appox $2100 ($4-6000 over 10yrs)

4 6v FLA L16 = 860a/h total. 215a/h daily cycle from 85% SOC gives the same daily capacity but only discharges to 61% At these levels you should get 10yrs+ life and the cost is $1300 so lifetime cost is close to 1/4 than the fireflies. The bonus is that you have that 61% available as a reserve if occasionally you have a high demand or poor charging.
As with all batteries the key to long life is not DOD but getting them FULLY charged at least 1 month preferably weekly. Any discharge not returned withing a month is likely lost for good and the idea that you can continuously cycle batteries only recharging to 85% DOD will rapidly kill any battery

Totally agree and this is how i went with my battery system. After nine year I'm on my second set of 6V GC31 batteries.


However I do have a question about the amp hour capacity. You give 860 amp hours for 4 X 6V batteries. Correct at 6V but if connected series/parallel for 12V that would only be 430 amp hours unless you're using some monster 6V and not golf cart size.
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Old 30-08-2019, 11:52   #12
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Re: Firefly Oasis : 2 years old and dead

L16's are around 430 each so 4 gives 860 @ 12v. I prefer to go with larger batteries but they do require good height, the L16 is the same footprint as a G31 but about 2x the height. Alternative is to go for 8 G31's but they will not be as robust.
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Old 30-08-2019, 12:00   #13
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Re: Firefly Oasis : 2 years old and dead

Quote:
Originally Posted by FredVeroMakani View Post
Well I guess next time I will go lithium. All my chargers are capable so I will not hesitate.

Lithium is a good option for boats with very high peak demands such as electric cooking, air con run off batteries, electric drive or very large inverters. Anything above about C4 discharge rate seriously reduces the capacity of a lead acid battery but Lithium will handle it no problems. Costs are extreme, technology on boats is still somewhat cutting edge but progressing rapidly and it requires a good level of technical knowledge to set the system up. It does not look 'plug and play' to me yet. If you have these sort of high demands or just have no room to fit normal batteries it may be worth looking into otherwise why spend the $.
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Old 30-08-2019, 13:14   #14
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Re: Firefly Oasis : 2 years old and dead

Quote:
Originally Posted by roland stockham View Post
L16's are around 430 each so 4 gives 860 @ 12v. I prefer to go with larger batteries but they do require good height, the L16 is the same footprint as a G31 but about 2x the height. Alternative is to go for 8 G31's but they will not be as robust.

Ok, you're going with the big ones. I don't have the height in my battery compartment nor the back to manage the weight. G31s will be my weapon of choice for the time being.
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Old 30-08-2019, 13:35   #15
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Re: Firefly Oasis : 2 years old and dead

I have eight total on two house banks; 4 and 4.....two years old, no issues they are so far better than what I expected.......I believe you had some damaged goods
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