FireFly Battery Long Term Users - Speakup

[Dave Lochner]

Originally Posted by Jetx

We're on our second set of 8x G31 Fireflies. The first set died after 1 year, having been connected to shore power and kept on float most of that time. We carried out the FF recommended restoration procedure several times, but the batteries didn't recover. To their credit, OPE and Firefly acknowledged these were from a bad manufacturing batch, and they were replaced under warranty.

Now, 18 months later, our second set is showing signs of reduced capacity, although not nearly as pronounced as before. This set of batteries was PSOC cycled between roughly 45%-85% for most of the past 18 months. During 8 months of cruising this year, they were only fully charged 4 or 5 days. (Flexible solar panels died, and we chose not to rack up the generator hours that would be required to get through absorption to 100%.) We performed the restoration procedure multiple times again at the dock, and the batteries recovered somewhat, but definitely not all the way back to original. Based on voltage sag, I'm guessing they've lost about 20% of nameplate capacity.

I admit these batteries have been abused, and we didn't come close to following Firefly's recommendations -- periodic fast charging at 0.4C, and a full charge every 2 weeks. Run-of-the-mill AGM batteries would likely have been destroyed by the treatment we've given these Fireflies. Still, given that PSOC operation is what FF batteries are meant for, I had hoped for better. My conclusion is that the Fireflies hold up very well under extended PSOC cycling, much better than most lead acid batteries would, but even FFs will permanently lose capacity if they're not fully charged often enough.

If you have enough solar capacity, or get to the dock often enough to charge them to 100% at least every few weeks, Fireflies will probably work beautifully. But if you don't, then LFP is probably a better solution.

Reading these stories, I think the key to Firefly longevity is deep cycling and fully charging them. In a recent email from OPE I was advised to:

"Best advice I have is to cycle them hard a few times to wake them up and also fully charge them. If you can hold the absorption charge at 14.4v until the current drops to .5a per battery - that is best. "

Depending on the bank size this may not be possible with shore power charging as each battery would need about a 40 amp charge source. To charge them properly it seems a high output alternator with a good programmable external regulator is essential.

[Paul L]

This thread really shows the Fireflys in a poor light. Besides the short life failures seemingly too high. The solutions to deep discharge, full recharge, do it X times a week, etc are exactly what Fireflys were marketed as not needing vs AGM batteries. Too bad, as I was considering them as a good, easy install instead of a more complex LiPo upgrade,

[sailorboy1]

As the thread OP i feel you should note

- there are lots of users on this thread reporting great operation, myself included
- you should note there are some common operations for failures showing in the thread, especially for users leaving the batteries sitting on float
- there appears to have been some manufacturing issues for a while, suppliers admit and have honored the warranty

[Dave Lochner]

Originally Posted by Paul L

This thread really shows the Fireflys in a poor light. Besides the short life failures seemingly too high. The solutions to deep discharge, full recharge, do it X times a week, etc are exactly what Fireflys were marketed as not needing vs AGM batteries. Too bad, as I was considering them as a good, easy install instead of a more complex LiPo upgrade,

The reports of poor performance on this thread come from a small number of boaters. I would be hesitant to generalize too much from these few reports.

For some boaters, Firefly batteries area good choice, but not for all. It is necessary to have sufficient charging capacity to ensure optimal performance. Stock internally regulated alternators won't make, the manual specifically warns against it. 20 or 30 amp chargers are inadequate too.

Firefly batteries share two important characters with LiFePO4 batteries: 1) ability to accept high charging rates, and 2) more useable capacity, 2 FFs have roughly the same usable capacity as 4 230 6v batteries at half the weight.

[sailorboy1]

The only reason I got my Fire Fly batteries was to get rid of the lost of capacity from being at partial state of charge. If not for that I would still be using golf cart batteries at 1/4 of the cost.

If a boat stays at a dock plugged in most of the time it is a waste of money to have “fancy” batteries.

IMO

[Dave Lochner]

Originally Posted by sailorboy1

The only reason I got my Fire Fly batteries was to get rid of the lost of capacity from being at partial state of charge. If not for that I would still be using golf cart batteries at 1/4 of the cost.

If a boat stays at a dock plugged in most of the time it is a waste of money to have “fancy” batteries.

IMO

Absolutely! We bought ours and a high out put alternator because we would be out cruising and infrequently tied to a dock. I expected the batteries to go through a few hundred cycles in a year and infrequently brought back to 100% SOC. This would have killed AGMs and beat up the GC batteries I had.

[Jetx]

Originally Posted by Dave Lochner

Depending on the bank size this may not be possible with shore power charging as each battery would need about a 40 amp charge source. To charge them properly it seems a high output alternator with a good programmable external regulator is essential.

To achieve a 0.4C charge rate, I disconnect half of the batteries from the ground bus, charge the 4 that are still connected, then swap ground connections and charge the other 4, then put them all back online. Of course this is only for the restoration procedure, not for regular operation. Not a big deal.

The tougher and far more time consuming part of the restoration process is the first step… draining the batteries down to 10.5 volts. This takes lots of time with a large bank, particularly when many of your “useful” loads refuse to run on as the voltage gets below say 11.5 (inverter, fridge compressor). I bought some old school halogen automotive fog lights from Harbor Freight just so I could finish drawing the batteries down in less than 24 hours.

[mjgill1]

[QUOTE=
Firefly batteries share two important characters with LiFePO4 batteries: 1) ability to accept high charging rates, and 2) more useable capacity, 2 FFs have roughly the same usable capacity as 4 230 6v batteries at half the weight.[/QUOTE]

That's partially true. They are good for what they are, but have pretty specific needs in order to maintain the warranty. If you're ok with LFP, they are less finicky. You just have to set up your charging system properly and perhaps get a DC to DC charger for a standard start battery. As a current short term cruiser that has weighed the option of Carbon Foam Tech, I am sticking with AGM for now. When I transition to long term cruising, e.g. live aboard, LFP will be for me
Here are some quotes from the Firefly battery manual that can be found on Ocean Planet's website: https://docs.google.com/document/d/1...h.4bv333pi1q1d

3.Read through this entire section for complete charging information. Failure to charge according to the recommended guidelines will void the warranty. Note that there needs to be a means to charge at a rate of 0.2C (24A for a G31) for the “Periodic Fast & Complete Charge Cycle” described below and achieving 0.4C charge current is preferred.

4.Max discharge Current: The maximum recommended discharge current is 0.7C for extended periods of time to ensure the longevity of the battery. The FF battery can discharge up to 3C for short periods.

5.Max Charge Current: The max recommended continuous charge rate is 0.5C but 1C can be tolerated for sporadic charge sessions. Frequently charging at 1C will negatively impact the battery's lifetime.

9.Float-Charging: For charging sources that may be charging the battery for an extended period of time (solar, or an alternator if motoring for a while); set the float voltage to 13.4V or 13.5V for the G31 and 4.5V for the 4V 450Ah model. Firefly batteries do not require a float charge on a regular basis. However, if you are float charging, due to their longer projected lifespan, it is important to keep the float voltage at 13.4V or 13.5V (4.5V for each 4V/450AH) to ensure the battery lasts for as many cycles as possible. For this reason, Firefly batteries are not recommended for applications using internally regulated alternators.

11.Periodic Fast & Complete Charge Cycle Recommendations: Note that periodic fast (high current) charging from a low state of charge can help restore usable capacity after periods of repeated slow charging (less than 0.2C) or deep discharge cycles. It is recommended that the battery goes through a complete charge cycle from a low state of charge every week if they are being heavily cycled or at minimum every 30 days. Ideally the batteries will be charged at a current of 0.4C (46 Amps for an Oasis G31) but a minimum of 0.2C (24A per G31 battery) is acceptable. These charge cycles should end with a 24 hour float charge at 13.5V for the G31 and 4.5V for the 4V 450Ah model. For applications lacking fast charging capability, contact OPE or for alternative restoration procedures.

Restoration Charge
As stated, Firefly Batteries can operate in a partial state of charge for long periods of time without sustaining any permanent damage. The usable capacity will decrease, however, with each cycle within a partial state of charge, up to a point. In order to regain the full original capacity and in some cases more, it is necessary to perform a restoration charge. To perform the restoration charge: charge the G31 to 14.4V or the 4V/450AH to 4.8V and continue to charge until the current drops to 0.5 A on the G31 or 2A on a 4V/450AH and apply a float charge of 13.5V(4.5V for 4V model) for 24 hours. Fully discharge the battery to 10.5V (G31) or 3.5V (4V/450AH), and then repeat the same charge cycle.

Hope this helps whoever.

[sailorboy1]

Originally Posted by sailorboy1

I have had my Firefly house battery bank for 1.5 years now with no problems.

But I would like to read long term users stories (yes I know there aren't a lot that would be on the forum). Especially ones who have had them 5+ years AND spent long (months) periods of not pugging into shore power.

Speak up with your story.

see above, time to reset the drift

[BAD ORCA]

I know i would not be considered a long term user yet, but thought i would share my experience so far since im intentionally abusing my Firefly.

Purchased a single G31 Firefly about seven or eight months ago. Using it as a start battery and temporary house battery for light loads when i stay aboard.

I cant decide if i should go lithium or firefly's for my future house bank so reason im abusing this battery, to see if it can really live up to the claims. If so i will postpone lithium and use firefly's for the house.

Basically since iv'e installed the battery i will use it and run down the voltage from fully charged (12.7ish volts) to anywhere from 12.5 to 11.5 volts over the course of one to several weeks, without charging it. The use will be random days when i happen to be aboard the boat. When i do charge it i would charge it sometimes fully, sometimes partially, sometimes float it, mostly not, and start the discharge cycle all over again. I charged it from shore power only at different amperages. Sometimes at 15Amps, sometime 30Amps (mostly), sometimes 45 and occasionally 60 amps. I have on many occasions gone 3+ weeks without charging it and mostly discharge it to around 12ish volts but have gone into the mid 11's on several occasions.

I did my first restoration charge last weekend. I used the battery as heavily as i could over the course of a week. By the weekend i had it discharged to around 12 volts. I then turned on everything i could and drew it down to 10.5 volts. I immediately recharged it at 60 amps and floated it for the recommended 24 hours.

Before i did this restoration charge i estimate i had lost approximately 25-30% usable capacity. After full recharges it was almost immediately dropping to 12.3 volts after an hour or two of light loads (3 amps).

I havn't done a 20 hour test but after the restoration charge iv'e seen a big improvement. I would estimate useable capacity is sitting around 90% at the moment.

I plan to do a second restoration charge this weekend. In Nigel Caulders review, they found out they had to do two consecutive restoration charges back-to-back to fully restore their Firefly bank during their testing. He estimated they got back more storage capacity after the second restoration charge than when they started, so we will see how it goes.

I've completely murdered two sets of brand new FLA's doing this same sort of testing in under a couple of months, one being brand new T-105's so i have to say im a bit impressed and hopeful for these firefly's so far.


I know this is not the long term usage being requested, but hopefully useful in some way.

[crayiii]

We've had six g31 firefly's in parallel for a year and change. We're full-time and have 1000 watts solar and 800 watts of wind.

Our issue recently is voltage sag in the mornings. Our Victron monitor reports we have pulled 200AH by morning and says we're at about 70% SOC. With a 10-15 amp draw, we're seeing 12.25 volts.

Maybe that's normal and I'm just paying more attention to the monitor lately but the voltage seems low to me.

[FlyingScot]

Originally Posted by crayiii

We've had six g31 firefly's in parallel for a year and change. We're full-time and have 1000 watts solar and 800 watts of wind.

Our issue recently is voltage sag in the mornings. Our Victron monitor reports we have pulled 200AH by morning and says we're at about 70% SOC. With a 10-15 amp draw, we're seeing 12.25 volts.

Maybe that's normal and I'm just paying more attention to the monitor lately but the voltage seems low to me.

First make sure they are at 100% S.O.C. based upon end amps at absorbtion voltage. That way the 70% is more likely to be accurate.

See this thread about sag. Post 2 shows what looks like an official SOC / Voltage graph. https://www.cruisersforum.com/forums...ag-225444.html

[crayiii]

Originally Posted by FlyingScot

First make sure they are at 100% S.O.C. based upon end amps at absorbtion voltage. That way the 70% is more likely to be accurate.

See this thread about sag. Post 2 shows what looks like an official SOC / Voltage graph. https://www.cruisersforum.com/forums...ag-225444.html

Yeah, I think you're right. I pulled up data and it looks like the chargers haven't been keeping them at absorption voltage long enough. I made some changes to things and the graphs are looking a lot better today. I'll see how this impacts us in the morning.

[phantomracer]

We just completed our 6th year of beating up our firefly bank (2xG31)

I take NO care of them (which is why I killed expensive rolls batteries in about 3 years) and they are performing well.

I WAS JUST about to post a new topic (and I still will, so I don't hijack this thread) on a restoration charge.

This season I did notice some minor performance degradation. Mind you, i would have gone through 2 sets of FLA batteries by now!

I pretty much torture them. Boat is on a mooring in the summer. We have refrigeration on board, full array of electronics, Autopilot (used a lot), etc.. The only charging it gets is pretty much when we leave and come back from our weekend cruises to motor back to the mooring, or into a port. But Refrigerator, AP, electronics on for hours under sail.. every weekend. If the battery bank gets a bit low on charge, the fuel cell kicks on to bring up the charge level .

I do throw a small 35w portable solar panel on to assist while left on our mooring when the boat is not being used.

I put the boat away 2 years ago with the batteries at about 60% (according to the Balmar smartgauge) and left it all winter, and used the lights etc all winter while in storage doing projects.. launched the boat without even putting it on charge.

Have not done a restoration charge yet, I will likely do it this winter.

For my needs, the firefly batteries rock. I am so bad at taking care of batteries, and these things are taking everything I can throw at them, after 6 seasons, I am starting to see some slight performance degradation. Hopefully they can be restored like new, as they are always touted to be able to do. They are out performing FLA by leaps and bounds in my unscientific real world torture test!

[phantomracer]

Originally Posted by Paul L

This thread really shows the Fireflys in a poor light. Besides the short life failures seemingly too high. The solutions to deep discharge, full recharge, do it X times a week, etc are exactly what Fireflys were marketed as not needing vs AGM batteries. Too bad, as I was considering them as a good, easy install instead of a more complex LiPo upgrade,

Eh, look at my post above.. I have done none of that, after 6 years they are performing quite well, albeit, does probably need a restoration charge now. But 6 years of zero care taken, even dropped to 10v once by accident, the batteries did not seem to care.

They are 99.9% drop in replacements for FLA/AGM batteries. Great value, as, in my case, my battery budget has been cut in half, and is still falling with each year.