[PSUBS-MAILIST] Lithium Batteries

[River Dolfi via Personal_Submersibles]

LiFePO4 batteries are definitely the way to go, the hard part is the price
tag. The good news is, depending on your usage case, they may actually be
more cost effective than an AGM.

Flooded lead acid and AGM's typically limit you to charging at ~0.2C. So a
100ah AGM battery could only be charged at a max of 20A, and would require
5 hours to fully charge.

A commercially available 100Ah drop-in LiFePO4 battery system (Like
Battleborn, Trillium, Relion, etc) can be charged happily at 1C, or 100A,
so a total battery charge can be done in an hour.

Typical PSubs usage is several short dives over the course of a day. You
may be able to get away with carrying less battery capacity simply because
you can charge the batteries significantly faster. Instead of spending
all-night charging in the hotel parking lot for a day's worth of diving,
you may be able to design a submarine around several short dives in one
day, with quick recharges in between.

I imagine it would be something like this:
Morning Dive- 3-4 hours
Recharge and Lunch- 1-2 hour
Afternoon Dive- 3-4 hours
Recharge and Dinner- 1-2 hours
Night Dive- 3-4 hours
Recharge, drinks, then sleep.

If I were building or owned a K250, or something similarly sized, this is
exactly what I would be doing.

-River J. Dolfi

rdolfi7 at gmail.com
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