[PSUBS-MAILIST] Lithium Batteries

[Alan via Personal_Submersibles]

River,
I have seen cost comparisons between lifepo4 batteries & lead acid over
their life time as energy storage batteries in solar / wind generation systems,
& the lifepo4 batteries came out on top.
In a previous post I made the left field suggestion that a submarine could
be  used as part of a house hold solar power system. To me this makes sense
as batteries are usually the biggest cost in an off grid system & don't get a lot
of use in a submarine! Great excuse to justify a bank of lithium batteries.
Alan


> On 10/04/2020, at 10:30 AM, River Dolfi via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 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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