LiFEPO4 vs Carbon Foam

[cat-keys]

Hello all


I am currently starting a project on our 2009 Leopard 40 catamaran to either fix or replace our Northerlights M673 generator or upgrade our solar from 5 x 85w to 5 x 140w rigid (similar size to the current 5 x 85 that are 10 years old) + 2 x 175w semirigid on the coachtop and add high amp alternators


the reason is two fold - the powerhead on the generator is broken, but the 630Ah Lifeline AGM battery bank we have does get down to 60-50% DOD since our Ah estimate usage at anchor is about 280Ah (pls dont reply "go on a power diet"). Its over 500 underway but can offset that with thge 80Amp Alternators.


the issue I would very much appreciate feedback on is battery technologies vs cost and expected cycle life

I have watched numerous youtube videos on Firefly carbon foam on pacific yachts as well as lifepo4 on custommarineproducts and other brands of lithium and I must admit if am still very confused


seems carbon foam can also handle DOD down to 80% and still have a decent cycle lifespan



Lithium may last longer, but the upfront cost is about 1/3 higher at about $8.99/Ah Lifepo4 ($899/100Ah example) vs $5.69/Ah Firefly ($660/116Ah example).



so if I have to buy 6 of these this would end up being about a $2000 difference. If I want to upgrade my usable Ah to perhaps twice that amount to be able to potentially run a soft start AC for the night for a few hours, then cost is significant and I wonder if it makes sense to move to LiFEPO4 vs Firefly.


is there any side by side neutral comparison of these two battery technologies that could help drive my decision?

[sailorboy1]

I just went through choosing comfortable with the charging dangers and “all between the 2 and got the FireFly because I wasn't comfortable with all my batteries being in 1 unit. But i think you are wrong about the pricing.

I got 4 FireFly G31 for $1953 for 464AH. Could have got 400AH system my batteries with BMS/BPS for $1900 from the Electric Car Parts Co.

[RickG]

What is your charging system - alternators, solar controllers, shore chargers? Can they be configured properly for LiFePO4? In 2017 we replaced solar controller and shore charger with Victron components, and the external regulator for the Balmar 110amp alternator with a Balmar MC-614 and went with 800ah Carbon Foam Firefly G31 batteries with a usage profile like yours. All of the charging sources are LiFePO4 ready. I did not feel at the LiFePO4 options were ready for prime time in 2017. That may have changed, but I have a 15 year battery bank and will look at other options when the time comes.

If it was me on a 40-foot cat in Miami, I'd repair the generator and replace the solar. Air conditioning is good. When the Lifelines are end of life replace the batteries with then current technology.

Cheers, RickG

[cat-keys]

Thanks RickG - we have a brand new Xantrex 2000w inverter charger so no issues charging LiFEPO4.



I see Relion 300Ah online at about $3200. so abnout $10k I am thinking of upgrading to 3 x 300Ah, then upgrading the solar from 425w to 1000w. Maybe another $3k



astly I am thinking of adding a climma 4200 btu mini AC just for our mast stateroom which only draws 35Ampsabout $1400


all in all maybe $15k vs a new generator which would be about the same but have to calculate diesel cost

[RickG]

Honestly, if you want air conditioning I'd just get a generator. My Honda 2000 with a long run adapter 3 gallon gas tank can run our 14KBTU air conditioner for 24 hours. It's quiet enough that I forget that it is running. We rarely run the air conditioner, so adding a built in generator is not on the list.

Cheers, RickG