400Ah Prismatic LFP Bank - Late 2010 Pricing:
4 X 400Ah Winston Cells = $1032.00
Shipping Cells = $250.00
Tyco EV200 Contactor = $79.00
House Power BMS Control Board = $75.00
BMS Cell Boards = $54.00
Aluminum for end plates/cell
compression = $64.00
3/8" Polycarbonate = $27.00
Anodizing of
Aluminum Case = $60.00 (minimum charge)
Nuts, Bolts, Threaded Rod, Washers etc. = $12.80
Bus Bar = $4.80 (Blue Sea)
Switches,
Alarm Buzzer, BMS case etc. $44.00
Terminals = $9.50
High Voltage Cut Relays $24.00
Total Materials (my cost) = $1731.60
Total at current cell pricing $2704.10
Things I already had (from lead days) that others may not:
Balmar Regulator for
alternator = $$$
Solar or
wind controller with fully adjustable voltage parameters = $$
Class T fuse = $
Benchtop DC Power Supply - 30A minimum (for balancing the cells) = $$$
HO
alternator with serpentine pulley kit = $$$$$$
We use our capacity to 80% DOD or about 315 - 320Ah's before charging.
Usable Ah's cost us $5.49 per Ah. If you factor in
current cell pricing that makes it; $8.58 per
usable Ah.. Usable Ah's is only a small portion of the cost equation and cycle life is a critical component.
We initially wanted high acceptance/fast charging and a
battery that holds voltage under load well, in a lead acid battery. I was leaning towards Odyssey TPPL's at that point in time but had been studying LFP since about 2008. Firefly was not yet out so the EnerSys TPPL was our potential choice.
4 - 100Ah Odyssey PCM2150's for a 400Ah AGM bank = $1613.44
(Just batteries I am not including the hold downs in that
price just the batteries)
Claimed Lab Cycles
Odyssey Cycled at 80% DOD = 400 Lab Cycles
Winston LiFePO4 at 80% DOD = 2000 Cycles (Today they claim 3000)
$$ Per Cycle Odyssey = $4.03 per cycle (@ 400)
$$ Per Cycle LiFePO4 = $0.86 per cycle (@ 2000)
Today the cells are 9 years old and are zeroing in on 1100 cycles, most of which went all the way to 80% DOD. Some went to 90% DOD and a couple times I let them go all the way to zero. At 0% SOC, just for the sake of experimenting, I started the 44HP
diesel 10 times, back to back, without so much as a hint of a struggle.
The cells have been capacity tested to 0% SOC every 50 cycles to track performance. These 2009 cells are still delivering well over 400Ah's or no perceptible change in capacity.
$$ Per Cycle LiFePO4 = $1.57 per cycle (@ *1100 / 80% DOD Cycling) *Actual cycles to 80% DOD
$$ Per Cycle Odyssey = $4.00 per cycle (@ *400 / 80% DOD)
*These batteries would likely never deliver 400 cycles in the real world yet even using
lab data they still cost more than we spent on LFP actual cycles to lab cycles.
Our LiFePO4 bank has shown no signs of any degradation and still exceeds the 400Ah rating even closing in on 1100 cycles.