Any two years reviews for Firefly batteries?

[john61ct]

Nope, FLA golf cart batteries in 2x6V pairs are the best deep cycle battery value by far.

Specifically Duracell (actually Deka/East Penn) from BatteriesPlus or Sam's Club. Deka labeled same batts also sold at Lowes.

And they are each 200+AH, whether before as 6V, or after serially connecting into 12V pairs.

Others in that bottom price range aren't as good, but also get local pricing on Trojan, U.S. Battery, Crown and Superior.

Rolls/Surette is a whole nother level.

[fxykty]

I considered replacing our AGM bank with FF - cost about the same in NZ and can handle PSOC much better, and deeper, than the AGMs. But the deal killer is voltage drop - what good is it to go to 20% SOC with FF if the voltage is 11.xx? My instruments crap out and everything works harder when the bank goes below 12.2 and some load draws big amps for a short while.

For those with FF, doesn’t the voltage drop negate the advantage of deeper discharge?

[jkleins]

Originally Posted by fxykty

I considered replacing our AGM bank with FF - cost about the same in NZ and can handle PSOC much better, and deeper, than the AGMs. But the deal killer is voltage drop - what good is it to go to 20% SOC with FF if the voltage is 11.xx? My instruments crap out and everything works harder when the bank goes below 12.2 and some load draws big amps for a short while.

For those with FF, doesn’t the voltage drop negate the advantage of deeper discharge?

I have worried about it but not seen it. I occasionally get to 11.8 or so in the morning before heading out and I have not seen any of the problems with my instruments (Furuno) that others report. I did notice some decrease in fan speed but that was all so far. Also it can really go down (11.0 or so) with a big load like the windlass or the coffee maker but when it is that low I just turn the engine or generator on when I do one of those things. I guess it depends on what other equipment you have. I still worry about it though so one day I will go to Lithium just to avoid that.
I certainly don't worry about the 12.0-12.2 and stuff. Everything seems to work fine around there.

[Suijin]

Well you have the option of taking them down to a lower state of charge which of course you should be able to avoid. Sizing your bank so that you were routinely *needing* to go substantially lower than 50% would be foolish.

I occasionally let my FF's go below 12v but that's when I'm at anchor and know solar will bring them back up the following day.

As I understand it, it's still not great for the longevity of the batteries even if it does not reduce their capacity in the near term.

I've been super happy with my FFs after about a year with one caveat; they really don't like heat. My bank is in my engine room so on long motors they will only take so much charge. I've had to find ways to ventilate the engine room as a result.

[Pegu Club]

Originally Posted by fxykty

I considered replacing our AGM bank with FF - cost about the same in NZ and can handle PSOC much better, and deeper, than the AGMs. But the deal killer is voltage drop - what good is it to go to 20% SOC with FF if the voltage is 11.xx? My instruments crap out and everything works harder when the bank goes below 12.2 and some load draws big amps for a short while.

For those with FF, doesn’t the voltage drop negate the advantage of deeper discharge?

We by comparison to many other cruising boats have a low amp consumption. Our big draws are our B&G Zeus 2, 7”, and our Engle fridge. When we use the windlass the engine is running so that is not an issue. So we have had no noticeable drop in voltage thus far. We do keep our on board systems to to a dull roar as it were, less to buy, less to do maintenance on or replace later. This in theory keeps the fun to work ratio in good order.

Fair winds,

[john61ct]

Originally Posted by fxykty

But the deal killer is voltage drop - what good is it to go to 20% SOC with FF if the voltage is 11.xx? My instruments crap out and everything works harder when the bank goes below 12.2 and some load draws big amps for a short while.

For those with FF, doesn’t the voltage drop negate the advantage of deeper discharge?

Most loads are fine. You can put in 12V to 12V converters (stabilizers) on circuits for those few that aren't.

For big amp loads you need more Ah.

Or go to LFP

[chowdan]

To firefly battery owners - If you did it over again, what would you change now that you've been using them for a bit?

[admiralslater]

Due to circumstances ,posted earlier I am doing it again just ordered 5

[Pegu Club]

We would go with FF again, they suit our purposes very well. No special needs when installing. The usable amp hours is hard to beat. We would have had to purchase one or two more non FF agm’s to get the required amp hour availability.

Fair winds,

[jkleins]

Originally Posted by chowdan

To firefly battery owners - If you did it over again, what would you change now that you've been using them for a bit?

Today I would do the same thing as I did. If I was ready to mess with installing a BMS I would probably go with Li just for the voltage stability and increased capacity for the space. I could probably get the same functionality for less $$ just by adding more capacity to my FF bank but I don’t have room.

[fxykty]

Originally Posted by admiralslater

Due to circumstances ,posted earlier I am doing it again just ordered 5

Does this mean your batteries did not recover after the crash event? Bummer.

[admiralslater]

No they did not recover. After I discovered the problem it took several months before I could institute the recovery mode A couple of the batteries came back to about 70 percent and others were done . I don’t blame FF at all I did consider Relion but was not sure about the details
The FF batteries were faultless for 3 years before the crash.
The acceptance rate on fb was higher than Relion according to Ocean Planet, due to the throttled lithium bms

[Pete O Static]

I was one of the early adopters and now into my third year with Firefly. Not sure what all the discussion is about regarding voltage drop. Mine behave identically to the Lifeline AGM’s they replaced in that regard.

Last year I stored the boat for hurricane season and forgot to disconnect the Bluetooth Victron Smart Charger from the bank. Subsequently, the BT was active the entire time. When I returned to the boat, battery voltage was at 9.8 volts. Certain death for any lead acid battery. I recharged the Firefly bank and they are running today just as well as they were before I “killed” them.

All my charging sources go to the Firefly’s. Solar, Alternator and AC charger. The Firefly’s then charge a run of the mill automotive starter battery via a DC/DC charger. Couldn’t be happier. I also run with one less battery in the bank of Firefly’s than I had with Lifelines due to more useable capacity.

When these batteries do eventually die, I will likely transition to Lithium as the costs keep falling and I would love to get rid of the weight. I would never go back to Lifeline AGM’s or FLA again.

[tanglewood]

I was looking at the FF web site and was hoping to find charge curves, discharge curves, charge current min and max specs etc. The info seemed light, overall.

Has anyone seen details on how they operate, charge, discharge, etc.?

They did have cycle life figures for 25C temp and different DOD levels, and the numbers were impressively high, but has it been demonstrated? We are all hoping for long cycle life out of LFP, but that’s not proven beyond about 2000 cycles. So I’m skeptical that the FF numbers are more proven, and suspect they may be less proven since there isn’t a swarm of researchers working on them over the past decade.

Anyone seen otherwise?

[FlyingScot]

Originally Posted by tanglewood

I was looking at the FF web site and was hoping to find charge curves, discharge curves, charge current min and max specs etc. The info seemed light, overall.

Has anyone seen details on how they operate, charge, discharge, etc.?

They did have cycle life figures for 25C temp and different DOD levels, and the numbers were impressively high, but has it been demonstrated? We are all hoping for long cycle life out of LFP, but that’s not proven beyond about 2000 cycles. So I’m skeptical that the FF numbers are more proven, and suspect they may be less proven since there isn’t a swarm of researchers working on them over the past decade.

Anyone seen otherwise?

https://oceanplanetenergy.com/wp-con...al-G31-L15.pdf

https://oceanplanetenergy.com/advanc...asis-group-31/

https://oceanplanetenergy.com/wp-con...ales-flyer.pdf


I recommend the L16+ for greater expected cycle life.