Thread: lithium ?
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Old 10-20-2019, 01:54 PM   #24
Gordon J
City: Hampton, va
Country: USA
Vessel Name: Didi Mau
Vessel Model: 2003 Ocean Alexander 456
Join Date: Jul 2015
Posts: 955
Dome questions

Originally Posted by stevemitchell View Post
I ended up converting my FLA house bank to LiFePO4 recently for a few reasons, all of which have been mentioned. Those include: space, weight, ease of maintenance, and most importantly to me, charge time.

I've written the whole thing up at Victron + Wakespeed + Battle Born power system and still have a follow on article left to finish on the Wakespeed stuff alone.

I don't expect these batteries to last 10+ years, but I do expect 2000+ cycles out of them without much degradation. That is still a long time for my use case - I would need to have fairly deep discharges for 200 days out of each year before I reached 2000, and that would be 10 years total.

I've had LiFePO4 and Firefly battery banks before on a different boat (see LiFePO4 power design, installing and using the LiFePO4 bank, and Firefly power system upgrade) and had plenty of time to love/hate parts of those systems too.

The Fireflys were great, but they only come in two sizes which limits many installs, including the boat I have now. They are even more sensitive IMHO to charging profiles than most drop-in LiFePO4 banks, so you have to make sure you have updated equipment everywhere, including generator/alternator/etc. They also were hard to get for a couple of years, and their manufacturing is in a different place than the original sets I had.

The standard LiFePO4 solutions from Victron and other major manufacturers can be quite a pain when it comes to all of the extra equipment you have to have around them, which you can see a part of in the article on my previous sailboat LiFePO4 setup. The sheer complexity of devices involved just for power really bothered me for long term use, let alone troubleshooting.

The drop in stuff I'm using now doesn't require that, but it has its own pros/cons, just like FLA, Firefly, or anything else. Reduced overall charge rates per battery, BMS cutoff issues, etc.

For me, it was worth spending the extra money to have the charging rate capabilities I have now. I can charge my entire house bank in 2 hours or less on engine - no generator required. I can go 2+ days on battery now, versus barely one with FLA, without charging at all. I also do not have to worry anywhere near as much about FLA discharge levels, water/electrolyte, and power in general, as we have a more robust system in my opinion.

I have talked to so many people about the benefits and problems with varying types of batteries and power systems - there is no real right answer or major reason to consider LiFePO4 over Firefly over FLA. It is a mix of everything from budget, space, usage, goals, and expertise.
After installing 900 amp hours of fire fly oasis batteries, I am curious about what you term to be their sensitivity to charge profile. I do not find them to be any more sensitive in set up then a normal AGM. Also, as you learned, they do charge faster than a normal AGM, and you can run them all the way to zero, without harming them. They advertise 4500 Cycles if only discharge to 50%. I reckon I will never have to buy batteries for this boat again.

About your lithium batteries, are they installed in the engine room. I am a bit concerned about the heat in my engine room and the coal location of my battery banks. My understanding was that lithium is even more sensitive to heat. Has that been your experience?
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