Firefly battery issues

[tfox2069]

Anyone else experiencing issues with Firefly batteries prematurely failing?

In 2019 I started kicking around the idea of installing Firefly G31 batteries in my Hunter 36 to replace aging 4D batteries and after some discussions here in forums I decided to install two of them in parallel for one large house/starting bank. On the advice of MaineSail I upgraded my charging system as well, both the shore charger and replaced the "dumb" original alternator with an 80 amp from Rodd and an external regulator.

Fast forward one year and one of the two Firefly batteries would hold no more than ~40ah, even after a careful restoration charge. The other battery was fine. The bad battery was confirmed as so by the local seller and replaced under warranty. I purchased an additional G31 Firefly and wired the bank or now 3 together in parallel.

Fast forward to fall 2021 and I noticed my bank underperforming noticeably while out on longer trips. I would reach my low voltage warning in my BMS way before I calculated it should be so. I finished the season and brought the batteries home for bench testing and careful restoration charges. Results: One battery is holding ~35 ah after a restoration, the second ~70, and the third restores to slightly more than its expected full capacity. Restoration is done with a 65 amp bench charger that can be manually adjusted for voltage so I can strictly adhere to the manufacturer's restoration charge instructions.

Interestingly, this article articulates almost exactly what I'm experiencing, and they had to have multiple replacements before they got Fireflies that worked as expected: Firefly Woes – Our Next Adventures and then article #3 in their Firefly series that indicated they finally got batteries working as expected Firefly Redeemed – Our Next Adventures .

System setup: Three firefly G31 batteries wired in parallel used as start and house for Hunter 36 sailboat with Yanmar 3YM30 diesel auxiliary. Boat is used occasionally for overnight or multi-day trips, but mostly day trips with shore power left on when at the dock and shore charger left connected to maintain batteries when away from the boat.

Shore charger: Sterling Pro Charge Ultra 60 amp charger set to custom profile for Firefly batteries per battery charge/float instructions in Firefly manual
Alternator: Externally regulated 80a alternator; Wakespeed WS100 regulator set to Firefly charge/float profile (available setting from factory) and field output set to 75%
Solar: One 160 watt panel with Victron MPPT 100/20 controller set to charge/float settings per instructions from Firefly

 

[Stu Jackson]

CF has had a lot of firefly discussions

FireFly Battery Long Term Users - Speakup - Cruisers & Sailing Forums

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

www.cruisersforum.com

Firefly battery bank restoration charge question - Cruisers & Sailing Forums

As mentioned on another recent thread here (I did not want to hijack that thread) , I am interested in doing a restoration charge on my firefly bank. Just looking for best practices and tips or tricks

www.cruisersforum.com

You could read more there.

 

[Hello Below]

Interestingly, this article articulates almost exactly what I'm experiencing, and they had to have multiple replacements before they got Fireflies that worked as expected: Firefly Woes – Our Next Adventures and then article #3 in their Firefly series that indicated they finally got batteries working as expected Firefly Redeemed – Our Next Adventures .

And in August 2021 they gave up on the Firefly and reported that they had ordered Lithium.
Firefly Part II: Electric Boogaloo

 

[tfox2069]

CF has had a lot of firefly discussions

FireFly Battery Long Term Users - Speakup - Cruisers & Sailing Forums

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

www.cruisersforum.com

Firefly battery bank restoration charge question - Cruisers & Sailing Forums

As mentioned on another recent thread here (I did not want to hijack that thread) , I am interested in doing a restoration charge on my firefly bank. Just looking for best practices and tips or tricks

www.cruisersforum.com

You could read more there.

That's an excellent thread Stu. One of the consistent conditions anecdotally quoted for killing the Fireflies seems to be boats sitting mostly at the dock with the batteries on float. That would match my typical usage. When I bought them I expected to be doing more cruising and using the PSOC advantage they offer but...work. Firefly does provide a recommended float voltage for them, which I honor, and with 12v only refrigeration its not feasible to turn them off when not at the boat.

Part of me is wondering whether the Sterling Pro is really fully charging them - even on the custom profile with the right voltages. The charger is not programmable for a multistage profile - e.g. (per Firefly) charge at 14.5 volts until the battery acceptance drops to 0.5 amps and then drop back to 13.5 volts for float, just voltages. I don't know enough about the charger to know how it behaves in that sense relative to what the Fireflies need (e.g. timed vs acceptance dropdown). I'm using a bench charger at home and doing it manually, but I can't do that on the boat - i'm stuck with the Sterling Pro profile. That is, unless I make the float charge the same as the bulk charge and then manually drop the float charge to the right level when I get to 0.5a acceptance. That just seems ripe for me forgetting when I leave the boat and killing all three batteries and making a mess from overcharging. .

What does make me scratch my head is the number of folks who just "set it and forget it" and the Fireflies seem to do fine. I'm apparently paying a LOT more attention to mine than many seem to be doing, with much worse results than some (except for the one battery that plods along).

If I can't get this to work out in this upcoming season it may be back to FLA from a high quality manufacturer, which is what Mainesail recommended to me in the first place, given my use case.

 

[jssailem]

Sterling Pro profile

Are you "stuck" with the Sterling Pro Charger or the Sterling Pro Charge Ultra?

If you have the "Ultra" model, then the following option applies.

• One custom, user programmable battery charge profile. Can be set from the charger, no need for a computer.

This is the feature that MaineSail has shared as the optimum value. You can set your profile so that it meets the specification sof the battery manufacturer.

 

[tfox2069]

Are you "stuck" with the Sterling Pro Charger or the Sterling Pro Charge Ultra?

If you have the "Ultra" model, then the following option applies.

• One custom, user programmable battery charge profile. Can be set from the charger, no need for a computer.

This is the feature that MaineSail has shared as the optimum value. You can set your profile so that it meets the specification sof the battery manufacturer.

I have the Pro Ultra - purchased from MaineSail, for the exact reason you state - setting the optimum custom values for the Firefly. I have always had that set up, but haven't been certain that its charging on TIME (the ubiquitious egg timer) or VOLTAGE, or ACCEPTANCE. I ran across a thread from Stu, I think, from some time back that seems to indicate its voltage - which might be OK, although acceptance would be better since the batteries need to drop to 0.5a acceptance until the charge is reduced to float according to Firefly.

Have the question into Sterling now and will post the answer.

 

[Stu Jackson]

I don't know enough about the charger to know how it behaves in that sense relative to what the Fireflies need

I have always had that set up, but haven't been certain that its charging on TIME (the ubiquitious egg timer) or VOLTAGE, or ACCEPTANCE. I ran across a thread from Stu, I think, from some time back that seems to indicate its voltage -

Have the question into Sterling now and will post the answer.

Here is the link to Maine Sail's article:

Installing a Marine Battery Charger - Marine How To

Choosing A Charger With battery banks getting larger & larger and battery technology becoming more and more expensive a quality battery charger is not the place you want to skimp on features or quality. *For this article we are installing a: Sterling ProCharge Ultra Battery

marinehowto.com

I'm pretty sure he answered your question about "How it works" in that article. This is just part of it:

The ideal charge algorithm, for marine battery chargers, has not yet been implemented


Why?
In order to have an ideal recharge the charger really needs to know what is a house load and what is going to the battery. Seeing as battery chargers only know output current, or more accurately the percentage of its power supply being used, as well as voltage, they can’t have any idea what is flowing into the battery and what is flowing to house loads. This makes implementing a voltage only algorithm difficult at best. Some chargers use smarter algorithms and some use fairly dumb egg-timer type algorithms.
The Sterling ProCharge Ultra uses a number of factors to adjust and adapt the duration of the absorption cycle to what it believes the battery needs. In terms of charge algorithms it works pretty well. A simple explanation is that the ProCharge Ultra examines the duration spent in bulk and can then add or subtract time spent in the absorption stage. This type of algorithm is certainly smarter than a simple egg-timer. While not perfect, it does a better job at keeping the batteries healthy than do many egg-timer based chargers.
In an ideal recharge a battery charger would not drop to float voltage until the battery bank had attained the 99.5% to 100% SOC point. Almost all battery chargers out there, for marine use, drop to float before the battery bank has attained 100% SOC. While this makes them “safe“, for the manufacturers lawyers, it also means that in order to get back to 100% SOC it just takes a bit longer. At a dock this is not a huge deal, if we are getting into the mid to upper 90’s before the float transition. Once the charger drops to float this dramatically extends the time it takes to get to 100% SOC. The absorption cycle is perhaps the most important stage of charging and if it is too short, due to an egg-timer, the batteries can become chronically under charged and suffer the effects of sulfation.
Unfortunately far too many chargers out there work on the simple “egg-timer” principal. Here’s how an egg-timer charger usually works.

 

[Maine Sail]

Sounds like you got a bad batch? That sucks but we've seen it with every brand.. have you talked with Bruce the US Importer?

 

[tfox2069]

Sounds like you got a bad batch? That sucks but we've seen it with every brand.. have you talked with Bruce the US Importer?

I have not, and wasn't aware of Bruce. I'm working with the local dealer - Coastal Climate Control in Annapolis. They replaced the first one in 2020, and are working with me on these next two. In each case they ask about the chargers and installation, including pictures if I have them. Fair enough. If its my fault with a bad installation or practices I wouldn't expect them to uphold the warranty. From what I can tell they put the battery on the bench and try a restoration, and probably some other tests. They did tell me that if they're able to restore the battery that I'd be responsible for associated labor fees, but they were unable to restore the capacity on the first one I returned in Jan 2021.

I was able to get one of the two batteries up to ~70ah capacity after one careful restoration cycle, so will give it another one or two tries before sending it back. But the other one is holding only around 35ah after two restoration cycles so I've given up on that one. I'm measuring the ah put back into the battery with a counter after depleting it to 10.5v under a 6 amp load, and then completing a full restoration cycle.

 

[tfox2069]

So in the interest of obsessing over this (since I can't be sailing right now), I'm wondering if I would achieve better balance in charging my 3-battery bank by changing from my current parallel schema to an adaptation of Impact Battery's "perfectly balanced charging" diagram (article here: How to Charge Lead Acid Marine and RV Batteries in Parallel | Impact Battery ). Thoughts? Disparaging remarks?

 

[jssailem]

No
NOT MORE BALANCED.
You will charge send a charge across the middle battery.
CURRENT SET UP IS BETTER.

 

[mermike]

Optimal is to have equal leads to common busbars. All positive cables the same length. All negatives the same length.

 

[Maine Sail]

I have not, and wasn't aware of Bruce. I'm working with the local dealer - Coastal Climate Control in Annapolis. They replaced the first one in 2020, and are working with me on these next two. In each case they ask about the chargers and installation, including pictures if I have them. Fair enough. If its my fault with a bad installation or practices I wouldn't expect them to uphold the warranty. From what I can tell they put the battery on the bench and try a restoration, and probably some other tests. They did tell me that if they're able to restore the battery that I'd be responsible for associated labor fees, but they were unable to restore the capacity on the first one I returned in Jan 2021.

I was able to get one of the two batteries up to ~70ah capacity after one careful restoration cycle, so will give it another one or two tries before sending it back. But the other one is holding only around 35ah after two restoration cycles so I've given up on that one. I'm measuring the ah put back into the battery with a counter after depleting it to 10.5v under a 6 amp load, and then completing a full restoration cycle.

Rob & Gretchen are excellent and will get you squared away.

 

[Johann]

So in the interest of obsessing over this (since I can't be sailing right now), I'm wondering if I would achieve better balance in charging my 3-battery bank by changing from my current parallel schema to an adaptation of Impact Battery's "perfectly balanced charging" diagram (article here: How to Charge Lead Acid Marine and RV Batteries in Parallel | Impact Battery ). Thoughts? Disparaging remarks?

View attachment 202279

This is what I am using with 3 batteries. The math works as long as all the interconnecting cables are equal length.

 

[Brad Hoff]

I have been having issued myself. Installed 3 Firefly 12v the fall before the pandemic. Boat did get left on float over the winter and I understand they do not like that. Was out for two weeks last summer and was not even able to get them to last overnight. I do not have my exact overnight usages but was running was several LED's, refrigeration (8amps), occasional water pump, and inverter to charge cell phones. I have done three restoration charges since then and still cannot get more than 4 hours before the inverter shuts off at 11v. I am using a MagnaSine MS2812 with 130 amp charge output. Engine charging is a Balmar 180 amp alternator with the new 618 regulator set at carbon foam. Also have the SG200 battery monitor and Bluetooth with phone app. Fisheries wants me to do restoration charge on each battery individually and check individual amp capacity. I have not had a chance to do this yet as It is going to take a long time. Getting these batteries to 10.5v is not easy with constant monitoring for several hours. Even when I set the inverter to 10.5 volts, there is still 11.5 resting volts left so have to take them down using the LED's. I am to the point where I am ready to dump these anchors and go to LiFEPO4. Over $1,800 spent and many hours trying to get them to work. Personally, I would not recommend these batteries.

 

[Davidasailor26]

Getting these batteries to 10.5v is not easy with constant monitoring for several hours. Even when I set the inverter to 10.5 volts, there is still 11.5 resting volts left so have to take them down using the LED's.

The capacity test should end when the batteries hit 10.5 V under the C/20 load. The voltage might bounce a little once that load is removed, but there’s still at 0% SOC; no need to drive them down with progressively smaller loads. See Battery Replacement - AGM

 

[Tater]

OK, so I am a day sailor and don't have a battery bank on my boat. I have watched this thread for a few days and have decided to add my 2 cents. I do have 40+ years experience in industrial electronics. In my occupation I do deal with battery banks. Wiring batteries in parallel creates problems because each battery is slightly different in voltage and available amperage. The result is a struggle between the batteries. An extreme example is one dead battery connected to good batteries. The good batteries take a dive. This could be a factor in the failure referenced in the OP.

If I needed a 12V battery bank with a high AH rating my solution would use single cell(2V) batteries, wired series. This is common practice in the industrial world. These batteries are normally flooded lead acid. The have heavy plates and are designed to last many years. I don't know if they can be AGM. Here is an example of a 200AH battery.
Single cell 2V 200A Deep Cycle Battery transparent tubular flooded VRL longlife | eBay

JMHO, AGM golf cart batteries are good. Anything marketed for boating is always overpriced.

 

[Davidasailor26]

Here is an example of a 200AH battery.
Single cell 2V 200A Deep Cycle Battery transparent tubular flooded VRL longlife | eBay

Sorry, I had to laugh at the marketing claim of “superfluous electrolyte technologies to offer a very high lever of reliability and a long service life”. It’s not everyday you see superfluous sold as a good thing.

In all seriousness though those cells are $149 per unit, so a 12V pack of them would be about $900. That’s not inexpensive. And to build a bank of more than 200 AH you’d still need parallel cells. I’m sure there are applications for them but I don’t know that they’re leaps and bounds better than what’s traditionally used on boats.

 

[Tater]

Sorry, I had to laugh at the marketing claim of “superfluous electrolyte technologies to offer a very high lever of reliability and a long service life”. It’s not everyday you see superfluous sold as a good thing.

In all seriousness though those cells are $149 per unit, so a 12V pack of them would be about $900. That’s not inexpensive. And to build a bank of more than 200 AH you’d still need parallel cells. I’m sure there are applications for them but I don’t know that they’re leaps and bounds better than what’s traditionally used on boats.

Somewhere I have seen that type in a larger AH. Also they are designed to have a 20 year life. We scrapped one of this type that was 12V and I used it at home for years. It died only when it was dropped during a move. The marine battery is good for 2-5 years. That is about standard for an AGM. The price I saw for the marine unit was $600. There may be a breakpoint on the cost. Now, I will research "superfluous". Thanks.

 

[tfox2069]

UPDATE
So, as mentioned in the MaineSail exchange above, I've been working on warranty replacement since initially notifying the local seller Coastal Climate Control in Annapolis, MD) of the battery issues on 31 Jan of this year. They processed my claim and put me in touch directly with the importer, Ocean Planet. We've had a good amount of back and forth, and I've supplied a lot of information regarding the batteries and my attempted restoration charges.

But we're almost 60 days into the process and I still don't have batteries. Ocean Planet has been very communicative, but they are clearly frustrated as the importer. As of a week ago Firefly had still not reviewed their application for warranty, and informed Ocean Planet that no batteries for warranty would be available until May. So it looks like I'll put the boat in the water in a few weeks with 1/3 of its battery bank. In May I expect to do some longer trips, including a circumnavigation of the DelMarVa peninsula, and will need my full battery capacity on board. Not a good situation.