Here's my "boilerplate" LFP summary, mostly from marine electrics discussion forums involving long-term users and professionals, with special thanks to Maine Sail (see below).
Any and all feedback is welcome, especially if more "canonical" information from the links cited conflict with my summary.
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Systems: OceanPlanet (Lithionics), Victron, MasterVolt, Redarc (Oz specific?)
Bare cells: Winston/Voltronix, CALB, GBS, A123 & Sinopoly
Best to size your cells for two parallel strings for redundancy, unless you have a separate reserve/backup bank. Don't go past three, or you may see balancing issues that affect long-term longevity, maybe four in a pinch.
Note nearly **every** vendor, also those of ancillary hardware touted as "LFP ready", gives charging voltages **way too high** for longevity.
My (conspiracy) theory is that manufacturers would prefer their cells get burned out in under 10 years.
EV usage is very different from much gentler House bank cycling. Most EV people talking "lithium-ion" mean other chemistries not as safe as LFP, much shorter lifetimes, and with completely different setpoints and behaviors.
My charge settings for LFP: 3.45Vpc, which = 13.8V max for 4S "12V".
The point is to look at the SoC vs Voltage chart, and avoid the "shoulders" at both ends, stay in the smooth parts of the curve.
Either "just stop" charging when voltage is hit, or if you want another couple % SoC capacity, stop when trailing amps **at your spec'd voltage** hits endAmps of .02C, or 2A per 100AH.*
Note even at the "low" max charge voltage, letting the charge source continue to "push" even low currents long past the endAmps point is **over-charging, and will** greatly reduce lifecycles.
So if you can't then "just stop", set Float well below resting Full voltage, at say 13.1V, but that is a compromise, and *may* shorten life cycles.
With LFP, you don't need to fill up all the way at all, as far as the cells are concerned. In fact, it is bad for them to sit there more than a few minutes. Therefore only "fill up" if consumer loads are present, ready to start discharging, ideally right away.
Many sources claim there is a "memory effect" from keeping charge voltage and ending point exactly the same every time lower than manufacturer specs, that can apparently over time lead to apparent lower capacity. The recommended fix is to "go higher, into the shoulder" every so often, similar to "conditioning" a FLA bank monthly. To prevent the issue, vary your setpoints a bit, sometimes go a point or two higher or lower, vary Absorb time a bit etc. There is no consensus just how serious the problem is.
Store the bank as cool as possible and at 10-20% SoC, or maybe higher to compensate for self-discharge, if not getting topped up regularly (I would at least monthly).*
Letting the batts go "dead flat" = instant **permanent unrecoverable** damage.
Same with charging in below 32°F / 0°C freezing temps.
Persistent high temps also drastically shortens life.
Charging at 1C or even higher is no problem, as long as your wiring is that robust, vendors may spec lower out of legal caution.
Again, going above 14V won't add much AH capacity, but will shorten life cycles dramatically.
And of course, we're talking about gentle "partial C" House bank discharge rates, size appropriately and be careful feeding heavy loads like a winch or windlass.
Following these tips, letting the BMS do active balancing is unnecessary and potentially harmful, just look for LVD / OVD and temp protection. Multiple layers of protection are advised if it is a very expensive bank, so you don't rely on any one device to keep working.
Check cell-level voltage balance say monthly to start, then quarterly, finally every six months if there are no imbalance issues, but only if that seems safe to you.
This thread is long but informative
http://www.cruisersforum.com/forums/f14/...65069.html
, make sure to give both Maine Sail and Ocean Planet your close attention.
Also MS' summary notes here
https://marinehowto.com/lifepo4-batteries-on-boats/
**Everything** at that site is worth reading, very valuable. He also has great articles in Practical Sailor. His new site under development transitioning the pbase content is here
https://marinehowto.com/support, feel free to make a donation to help with those expenses.
Best of luck, and do please report back here!
