FireFly Battery Notes II

[Adelie]

Originally Posted by freshalaska

Someone please explain to me what .4c and .2c means.
Thank you!

Originally Posted by sailorboy1

C = battery 20hr discharge rating in amp-hours (AH), for the FF G31 each is 116AH so 0.2C is 116x0.2=23.2amps

SB1 explained for a single battery.

For a bank of several batteries where the batteries are wired in parallel, C is the sum of all the batteries 20-hr capacities so for 3 G31s in parallel that's 3 x 116 x 0.2 = 69.6A.

For a bank with batteries in series and parallel the batteries in series act as a single battery to deliver the desired voltage, so count the strings that are in parallel. An example of this would be 6v GC2 batteries, 225Ahr capacity wired to produce 12v. So each string is 2 batteries to get the 12v. If you had 6 batteries in the bank then 6 batteries / 2 batteries/string = 3 strings. So C = 3 strings x 225Ahr = 675A x 0.2 = 135A.

The only time you would see more than 2 batteries in series on a boat is if you were using odd voltage batteries such as 4v or 2v to get 12v or using a higher voltage system such as 24v, 36v or 48v. Then you would see more batteries in each string. The 36v and 48v systems are only typical for folks with electrical propulsion but there are occasionally folks that set up higher voltage systems for their own reasons. Voltages higher than 48v are rare on boats for safety & liability reasons, 60v and up is considered "high" voltage.

[chris95040]

Anyhow, the original Firefly inventor has told us that fast charging does improve the electrochemical processes inside the battery

Sorry for the thread drift but this caught my eye.

Sounds like Firefly no longer has relevant chemistry and materials science expertise in-house? Yikes.

Zombies like that are fine if it’s pretty simple and straightforward product, but do carbon foam batteries fit in that category? When cost pressures suggest a tweak to a manufacturing process, who is there to -understand- the impact on performance and safety? The trade school sparkies in quality assurance? The folks answering the phone?

I had planned to switch to the Firefly this spring but now I’m rethinking this. Hmmm.

[sailorboy1]

Originally Posted by chris95040

Anyhow, the original Firefly inventor has told us that fast charging does improve the electrochemical processes inside the battery

Sorry for the thread drift but this caught my eye.

Sounds like Firefly no longer has relevant chemistry and materials science expertise in-house? Yikes.

Zombies like that are fine if it’s pretty simple and straightforward product, but do carbon foam batteries fit in that category? When cost pressures suggest a tweak to a manufacturing process, who is there to -understand- the impact on performance and safety? The trade school sparkies in quality assurance? The folks answering the phone?

I had planned to switch to the Firefly this spring but now I’m rethinking this. Hmmm.

I will say i asked the manufacturer a question once and got a non answer reply. I doubt this is any different from lots of battery manufacturers as far as how batteries apply to boat use.

The only real reason to switch to FF IMO is if you plan to be off grid and experience a lot of partial state of charge use. If so and you are concerned about that there are only 2 choices, FireFly and LFP. I doubt the LFP suppliers have more answers than FF.

Us boaters have to figure this out. It will take 10 years at least probably.

I have the FireFly batteries. The math on them based on claims is they should last 20+ years. If they last 10, but I don't have to worry about psoc anymore i will consider it a good choice.

[Jetx]

Originally Posted by BillKny

Your solar controllers have no direct way of knowing what the tail current actually is because they can not know what amount of power they produce is going into the batteries and what is going out to loads.

If you have a Victron BMV battery monitor and a CCGX, they can all be linked, and the solar controllers can see the measured current going in/out of the batteries, and can be configured to drop from absorption to float at any tail current you like. You just have to enable what Victron calls DVCC - distributed voltage and current control - which works quite well.

We have 8 x FF group 31’s and can only charge routinely at 0.2C with generator or shore power (120A from Victron Multiplus + 60A from standalone charger). To perform the 0.4C recovery charge in the past, I’ve simply disconnected the ground cable from four of the batteries, charged the remaining four, and then swapped/repeated. It’s a hassle, but not too bad. Just have to be sure all charging and all DC loads are disconnected before you go swapping cables.

[Skipper Lee]

I am wondering if the Charger I bought with my Thunderstruck 5 Kw e-drive system will work fine with the 4) G31 Fireflies that just I bought for my conversion? BTW Its a Balboa 27 ft 4900 lb sloop.
I have the drive system installed now (yet to be used) and after checking out threads here I decided it was better to upgrade to the Fireflies.
When I bought the conversion kit I told them I was going to use lead acid and was sold the TSM2500 non can controlled charger. There is a Can controlled charger available.
I inquired to Thunderstruck as to the effectiveness of the charger using Fireflies and was told it should work fine and the non can controlled just means if I change to other than lead acid it wont be able to change the outputs to suit other types.
I find I am worrying now that I perhaps jumped in to quickly and this charger isn't what I truly need.
The charger I now have is the Thunderstruck Motors (TSM2500 48 V non can controlled) charger.
I am good at some things but after reading these forum comments I recognize that I have no idea about charging and charger selections.
I am truly scared about ruining the 6 Fireflies (2 House) (4 drive) as they cost as much as I paid for this project boat.
I see so many graphs, read about so many things I haven't got a clue about that I wake up scared.
It's just that the comment,Should work fine is not at all comforting.

Has anyone used this TSM 2500 charger with the Fireflies?
Can I get a suggestion of what charger to buy for the Firefly house bank? I don't have one yet!
If I hear it wont work for the 48V drive batteries what should I have bought?
Here's the link to the charger I have,

https://www.thunderstruck-ev.com/tsm...v-non-can.html

I am looking for as simple as possible, Plug in at the dock and use a 2000 watt inverter when anchoring.
PS
I do not have much room for solar but will also fit what's possible for the house bank.
Hoping to be reassured about this charger or???

[Adelie]

Originally Posted by Skipper Lee

I am wondering if the Charger I bought with my Thunderstruck 5 Kw e-drive system will work fine with the 4) G31 Fireflies that just I bought for my conversion? BTW Its a Balboa 27 ft 4900 lb sloop.
I have the drive system installed now (yet to be used) and after checking out threads here I decided it was better to upgrade to the Fireflies.
When I bought the conversion kit I told them I was going to use lead acid and was sold the TSM2500 non can controlled charger. There is a Can controlled charger available.
I inquired to Thunderstruck as to the effectiveness of the charger using Fireflies and was told it should work fine and the non can controlled just means if I change to other than lead acid it wont be able to change the outputs to suit other types.
I find I am worrying now that I perhaps jumped in to quickly and this charger isn't what I truly need.
The charger I now have is the Thunderstruck Motors (TSM2500 48 V non can controlled) charger.
I am good at some things but after reading these forum comments I recognize that I have no idea about charging and charger selections.
I am truly scared about ruining the 6 Fireflies (2 House) (4 drive) as they cost as much as I paid for this project boat.
I see so many graphs, read about so many things I haven't got a clue about that I wake up scared.
It's just that the comment,Should work fine is not at all comforting.

Has anyone used this TSM 2500 charger with the Fireflies?
Can I get a suggestion of what charger to buy for the Firefly house bank? I don't have one yet!
If I hear it wont work for the 48V drive batteries what should I have bought?
Here's the link to the charger I have,

https://www.thunderstruck-ev.com/tsm...v-non-can.html

I am looking for as simple as possible, Plug in at the dock and use a 2000 watt inverter when anchoring.
PS
I do not have much room for solar but will also fit what's possible for the house bank.
Hoping to be reassured about this charger or???

That charger will not work for both house and traction banks. The charger is 48v nominal so it will work for the EP bank. The house bank is 12v I assume and will require a different charger or something like a stepdown echo charger.
The charging profile shown for 48v is weird and I don't have the time to research it. Probably fine.
The max amps is somewhat concerning, they like to be charged at something like 0.3-0.4C. For a 116Ahr battery that would be 35-46A. 25A is probably OK at 0.22C. SB1's first post in this thread quotes FF support: "We do encourage folks to upgrade at least one of their charge sources if they are getting FF so that a minimum of 0.2C charge current can be achieved."
My guess is you fine with the EP. Charging at .22C instead of .3-.4C will probably cost you some life but not a lot.

If you wanted a bigger charger the only things I can find for 48v are forklift chargers that run off of 208/240v AC
48 Volt 50 Amp | Forklift-Battery-Charger.com

Of bigger concern is the house bank. Assuming they are in parallel, that gives you a bank size of 232Ahr. That means you need to a 45A or larger charger. The total wattage will be less than the EP bank but it still needs to be the higher amperage. Examples:
https://invertersrus.com/product/cotek-cx1250/
https://invertersrus.com/product/kisae-ac1260/
https://invertersrus.com/product/samlex-sec1250ul/

Both chargers running at the same time will be putting about 1800W into the battery which means somewhat more is drawn from the shore power. Figure together they will be drawing 20A from shore service. That means being careful to not use shore power for much other than charging when your first plug in. If the shore power is at all dodgy then you probably don't want to use the power for anything else and maybe stagger your charging by an hour, that it start the EP bank first and when demand for that tapers down some then start charging the house bank.

If you are charging off of a Honda 2200 then you will only be able to charge the EP bank initially then add the house bank an hour or so later. The EP charger will be drawing 1300-1400W initially, and the max continuous rating on the Honda is 1800W. That would be able to push a 30-35A charger if you could find one.

[sailorboy1]

Was away from boat last week so there was reduced power load and solar got batteries completely charged a couple days in a row. This was low charging current, but at 14.4V. Add it kept it there for 5 hours (if amps get real low it drops to float and doesn't cook the batteries). Now that I am back I can see that morning voltage is higher than prior at same power out.

My conclusion is that just like any lead acid battery, FireFlys like long low amps at absorption. Maybe the high current does make a difference for capacity recovery starting at a low state of charge. But for everyday operation holding the 14.4V is the goal.

This of course is my personal opinion based on off grid live aboard use.

[rgleason]

Maybe the change was due to two reasons:
1. Marketing higher charge rate.
2. Some technical solutions to loss of capacity that was being experienced by some users.
It becomes an additional tool to maintain the FF and it looks more attractive to users who are interested in higher charge rates with alternators as compared and competing with LFP/BMS.

[sailorboy1]

Maybe, as the marketing for AGMs says they charge faster but that only applies at a small point of SOC and is nothing of practical cruiser use really. Plus in my correspondence with Ocean Planet they hint that this helps them sell higher charge capable "stuff"

[Sternwake]

Notes of trends and tendencies in actual usage over time, is priceless.

Thanks for sharing.

Does firefly spec a maximum charge rate?

[OceanPlanet]

From the Firefly manual:

"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."

So there is such a thing at too fast...

[sailorboy1]

I was off the boat for a few days again recently, which means power usage was down. During those days solar really could keep charging at the higher end on the SOC and the batteries stayed at absorption voltage for hours. They never got t the 14.4V and 0.5amps charge rate, but probably got to 1-1.5amps a couple of times. Just like last time I was off boat and this happened I can tell from morning voltages that the batteries appear in better condition. They have the same characteristics if my old T105s back when healthy.

So IMO you should plan to operate your FireFly batteries just like you would any FLA/AGM batteries with the exception of worrying about getting 100% everyday. But getting there every 1-2 weeks appears to be worth doing it. far as the "doesn't suffer from Partial state of charge", wouldn't know that for years.

Overall I am happy with them as they provide the power I expected and I am not thinking about them as much.

[rgleason]

Originally Posted by OceanPlanet

From the Firefly manual:

"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."

So there is such a thing at too fast...

Can you please explain this a bit more? Thanks.

[OceanPlanet]

Originally Posted by rgleason

Can you please explain this a bit more? Thanks.

It's fairly universal for all battery mfgs to recommend a limit in charging current. Pitfalls of charging too fast can be overheating, excessive gassing, the increasing chances of internal corrosion, etc.

[rgleason]

Is charging at 0.5C on a regular basis acceptable?