Upgrading to LiFePO4

Maine Sail · Jun 14, 2020

Tim,

Start with this article and focus on the non DIY stuff such as "Drop-In" batteries. Keep in mind LiFePO4 are anything but drop-in replacements for lead acid. Warning: The article below is long, in-depth and covers a lot of ground including alternator considerations. The article below barely scratches the surface of LiFePO4. What ever you do don't cut corners on an LFP system. Victron is good so you're starting down the right path. Mastervolt is also good and Lithionics is about the best you'll get.

LiFePO4 Batteries On Boats

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kjretlaw · Jun 15, 2020

For all you'd spend to convert to LiFPO4 batteries you could just drop in a few Firefly Carbon Foam batteries and get a comparable amount of amp hours. Firefly Oasis Battery - Carbon Foam AGM I have a 32' and plan or replacing my batteries with Firefly before we start cruising on longer trips.

Maine Sail · Jun 15, 2020

kjretlaw said:
For all you'd spend to convert to LiFPO4 batteries you could just drop in a few Firefly Carbon Foam batteries and get a comparable amount of amp hours. Firefly Oasis Battery - Carbon Foam AGM I have a 32' and plan or replacing my batteries with Firefly before we start cruising on longer trips.

Firefly are excellent batteries and a good option to LFP but they are not LFP. To get your money's worth out of Firefly, you'll need temp compensated charging, for every charge source, and sources that are custom programmable to 14.4V and 13.2V to 13.4V. You'll also want at least one charge source that's capable of supplying .4C in charge current or 40A per 100Ah of battery. Stock alternators, solar controllers and chargers without temp compensation are not well suited for charging Firefly batteries.

dlochner · Jun 16, 2020

Maine Sail said:
Firefly are excellent batteries and a good option to LFP but they are not LFP. To get your money's worth out of Firefly, you'll need temp compensated charging, for every charge source, and sources that are custom programmable to 14.4V and 13.2V to 13.4V. You'll also want at least one charge source that's capable of supplying .4C in charge current or 40A per 100Ah of battery. Stock alternators, solar controllers and chargers without temp compensation are not well suited for charging Firefly batteries.

I've been considering changing from 4 GC batteries to 2 Firefly batteries. The latest version of the manual suggests charging the batteries at .5C (manual attached). The folks at Coastal Climate Control suggest a minimum of 25 amps per battery to bring them back to full charge. So, I'm still debating on what to do.

jviss · Jun 16, 2020

dlochner said:
The latest version of the manual suggests charging the batteries at .5C (manual attached).

No, it does not. The manual you attached says "The maximum recommended sustained charge current is 0.5C." It also says "If continuously deep cycling, then ideally once a week the batteries should be charged at a current of 0.4C (40 Amps for a 100 Ah battery) or 0.2C (25A per G31 battery) at minimum."

So, for a restorative charge it's 0.4C minimum, and 0.5C maximum sustained charge.

What this means in real-life terms is that you bulk at 0.4 to 0.5C, once it hits the absorption phase at 14.4V (for the G31), current will drop of with continued charging; stop at 0.5C.

By the way, I don't see the mystery or danger here with a smart alternator setup with temp compensated charging. And, while solar won't give you the 0.4C bulk you'd like occasionally, they will charge them up, and won't do any damage (per the manual). (This assumes you can deliver 0.4C times the number of batteries in parallel, or if you can isolate them for the restoration charge.)

If you don't have a smart alternator setup, only shore power and/or solar, you won't be able to properly perform the restoration charge, unless you spend a fortune on a shore power charger that can deliver 0.4C

Maine Sail · Jun 16, 2020

jviss said:
What this means in real-life terms is that you bulk at 0.4 to 0.5C, once it hits the absorption phase at 14.4V (for the G31), current will drop of with continued charging; stop at 0.5C.

You stop when the charge current has dropped to 0.5A at 14.4V, not at 0.5C.. Stopping at 0.5A at 14.4V is 0.0043C or .43% of Ah capacity. In otehrwords the battery is full when the charge voltage is at 14.4V and the tail current is at 0.5A..

jviss · Jun 16, 2020

Maine Sail said:
You stop when the charge current has dropped to 0.5A at 14.4V, not at 0.5C.. Stopping at 0.5A at 14.4V is 0.0043C or .43% of Ah capacity. In otehrwords the battery is full when the charge voltage is at 14.4V and the tail current is at 0.5A..

Yes, typo on my part.

Rick D · Jun 16, 2020

jviss said:
By the way, I don't see the mystery or danger here with a smart alternator setup with temp compensated charging. And, while solar won't give you the 0.4C bulk you'd like occasionally, they will charge them up, and won't do any damage (per the manual). (This assumes you can deliver 0.4C times the number of batteries in parallel, or if you can isolate them for the restoration charge.)

If you don't have a smart alternator setup, only shore power and/or solar, you won't be able to properly perform the restoration charge, unless you spend a fortune on a shore power charger that can deliver 0.4C

So, what you are saying it appears is that you would not recommend investing in Firefly tech batteries unless you extensively modify your charging sources. So, in my example, they will last about 4 times the life of my AGM's for about twice the cost IF all of the charging protocols are in place. Thinking about it, it doesn't appear worth the investment.

jviss · Jun 16, 2020

Rick D said:
So, what you are saying it appears is that you would not recommend investing in Firefly tech batteries unless you extensively modify your charging sources. So, in my example, they will last about 4 times the life of my AGM's for about twice the cost IF all of the charging protocols are in place. Thinking about it, it doesn't appear worth the investment.

I wasn't really saying that; it depends on your starting point. If you already have a high output alternator and smart charging regulator I think you can make it work. If you don't you'll have to evaluate the addition cost of those, plus the change in charging "lifestyle." If I was at a dock and plugged in I wouldn't do it.

Rick D · Jun 16, 2020

jviss said:
I wasn't really saying that; it depends on your starting point. If you already have a high output alternator and smart charging regulator I think you can make it work. If you don't you'll have to evaluate the addition cost of those, plus the change in charging "lifestyle." If I was at a dock and plugged in I wouldn't do it.

Balmar, Heart charger/inverter, but at the dock on shore power.

jviss · Jun 16, 2020

Rick D said:
Balmar, Heart charger/inverter, but at the dock on shore power.

Do you do any extended sailing where you're on the hook, i.e., not plugged in for a week or two at a time?

Rick D · Jun 16, 2020

jviss said:
Do you do any extended sailing where you're on the hook, i.e., not plugged in for a week or two at a time?

SoCal, so rarely on a hook; I have a mooring in Catalina where we stay for several weeks two or three times a year. 500 watts solar plus I carry a Honda 2000. The rest of the time it's hooked to shore power typically or I'm going to Mexico which is about 1/2 sailing, the other half motor sailing. So, it still doesn't seem worth it.

Davidasailor26 · Jun 16, 2020

(With apologies for the drift from lithium to FLA)

Any thoughts or experiences on how the Victron Super Cycle AGM’s ( Gel and AGM batteries - Victron Energy ) compare with the above options? They claim 700 cycles at 60% discharge, so better than twice my existing Deka AGM. Is this a way to get about halfway to the performance of Firefly with any less dependency on specialized charging?

JK_Boston_Catalina310 · Jun 16, 2020

I converted to LiFePO4 about a year and 3 months ago. I went with a DIY system following much of @Maine Sail recommendations. Here are a few things I have to offer:
1) don't consider it if you aren't a bit of a nerd,
2) don't consider it if you aren't a full-time liveaboard on a mooring or anchor,
3) don't consider it if you are not willing to change all components of your charging system (solar controllers, alternator and shore power charger) and,
4) don't consider it if you can't keep lead acid batteries for at least 5 years.

If you're still interested, read the Marine How To article over and over until it makes sense. Then you can start looking at other sources.

Honestly they are a great upgrade, if you put in the time. If you don't, I have met several cruisers who have thrown thousands of dollars away drying to do something other than a full system change. I have even killed a well made, expensive alternator not following all of the recommendations.

JK_Boston_Catalina310 · Jun 16, 2020

Tim22 said:
I have read Maine’s excellent article on LfFePO4 on boats and while I will not claim complete understanding, I did understand enough to know that I will not be doing a DIY! This leaves the factory integrated or system integrated battery system. My preference is probably for the factory integrated on the basis that I only have to deal with one manufacturer when things go wrong. Victron Lithionics and MasterVolt would be possibilities. I am particularly interested in Lithionics as I have huge respect for Maine’s research and recommendation of their system. My main focus is to end up with a long lasting, safe and reliable system.

Tim

I have a friend that reps Lithionics. Send me a PM if you want me to put you in touch. But be prepared that they are expensive. Likely over $5,000 for a 200 Ah system.

Good luck

Rick · Jun 17, 2020

Maine Sail and his expertise is beyond reproach. He is the "Mythbuster" of the marine world. Three years ago, when I was going to Lithium, and an upgraded alternator, Rod (MS) was nice enough to talk to me on the phone for over an hour. He prefaced the conversation with, I dont consult on lithium however these are my thoughts. Have not talked in a while, and there has been alot of progress made. My setup has nothing to do with MaineSail.
So if you are not a nerd, lol, and you want to take a calculated risk, you can do what I did three years ago and is still going strong. 4 Battleborn 100amp LifePO4s. A 100amp Balmar that I bought from him with an externally programmable controller. After 3 plus years of plug and play, my new Balmar sg200, which replaced my Victron 700, says my SOH (state of health is 96%). And we are the test track of bafoonery. We have flagged them twice, because after a day of sailing, we forgot to turn shore power ON after getting distracted on the dock. Oh and ran two spaceheaters! My inverter/charger does not have a Lithium setting. I let the BMS on the batteries do its thing. Now is this optimum? No. But they are tough little buggers and still going strong with an upgraded alternator and plug and play. I accepted the risk with my investment. We do not live on the boat. Not even near it. She sits on shore power (because we leave an ARB fridge on so we have a cold one upon arrival). with a backup solar panel on, just in case, sometimes for a month.

Cheers

jviss · Jun 17, 2020

Rick said:
We have flagged them twice,

What does "flagged them" mean?

Rick · Jun 17, 2020

jviss said:
What does "flagged them" mean?

Drained them until the built in battery management system (BMS) shut them down to save them!

Upgrading to LiFePO4

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