Expenses For Battery & BMS:
I can't wrap my head around the affordable part. Even if you can discharge them to 100%, that's an awfull amount of $ for batteries.... Must be the yankee in me.
Thunderstruck has a pretty good excel sheet that may assist you in determing what KW drives you would require for your boat. Unlike the folks in the booth next to MS at last years boat show, Thunderstrucks sheet takes stuff like continous run time & Perkerut into acount for minutes of operation based upon amp hours & DOD. May be a good starting point for you.
4 - 400Ah Winston Cells = $1032.00 (today's cost $2100.00)
Shipping Cells = $250.00
Tyco EV200 Contactor = $79.00
House Power BMS Board = $75.00 (Clean Power Auto LLC.)
Cell Modules = $54.00 (Clean Power Auto LLC.)
Aluminum for end plates/compression = $64.00
3/8" Polycarbonate = $27.00
Anodizing Aluminum = $60.00 (minimum charge)
Nuts, Bolts, Threaded Rod, Washers etc. = $12.80
Solar and Alt HVC relays = $8.60 (Cole Herse 70A)
Bus Bar = $4.80 (Blue Sea)
Switches, Alarm Buzzer etc. $44.00
Terminals = $9.50
Total Materials = $1720.70
($2780.00 at today's prices)
Compare that to a bank like this:
4 - 100Ah Odyssey PCM2150's for a 400Ah AGM bank = $1509.60
(note I am not even including the hold downs in that price just the batteries)
"Claimed Cycles" (disclaimer: I don't believe either of these "lab" derived claims and do believe they will both be lower in real world use.)
Odyssey Cycles at 80% DOD = 400 Cycles
Winston LiFePO4 at 80% DOD = 2000 Cycles
$$ Per Cycle Odyssey = $3.77 per lab cycle
$$ Per Cycle LiFePO4 = $0.86 per lab cycle
In the real world I had a bank of Odyssey's on a cruising customers boat die at less than 150 cycles to 50% DOD from chronic PSOC use (no solar on a mooring). This makes his battery cost $10.06 per cycle
My 400Ah LiFePO4 bank just surpassed 800 cycles most to 80% DOD and is still testing at more than 416Ah's (about 425 Ah's when brand new).. If I based my cost per cycle just on these 800 cycles alone it is already at just $2.15 per cycle with no usable capacity loss. If I had been using lead acid batteries, the way my customer was, who got 150 cycles, I would have been through 5 400Ah banks at a cost of $7545.00 and that is Ah to Ah..
You'd need an Odyssey bank of 900Ah to equal my 400Ah LiFePO4 battery because 80% DOD is murder in a PSOC environment......
When boaters do the actual math on how many deep cycles
they physically do before their lead acid batteries are dead they are usually shocked.
In a recent survey of more than 1000 sailors on battery use 79.5% of responders cycled their banks to 50% DOD less than 25 times per year. Stack that on-top of the fact that 82% of responders reported less than 6 years battery life and that means the vast majority of boaters are getting less than 150 real world cycles
out of their marine batteries... Ouch! Keep in mind that many of these companies claim 1200 "lab cycles" and these batteries are still failing in less than 150 cycles in marine use....
Still LiFePO4 is not for everyone
but when you compute the actual math
it usually costs less, not more
. Yep tough pill to swallow up front
but it pays back over the long haul.....