Originally Posted by Maine Sail
Damn with that small bank you are going to pass me in no time. I just broke 231 cycles today...... With a 400Ah bank I can discharge to 80% DOD in about two hours but to charge takes me 5+ unless I want to lug my 100A charger
into my office. So 1 per day max for me and if I am around then occasionally two.......
Your voltages match mine quite closely but I suspect those are not long rests.
My bank is currently sitting at 74.6% SOC (approx 21 hours) and is resting at:
The difference may be that I am drawing this cycle down at 11.5A - 12A which barely touches it...... I suspect I may get 500Ah at 11.5A - 12A out of this 400Ah bank.......
I finally completed my 0.03C test to simulate our own boats max avg loads. The results are in.
The bank puts up 441 Ah's at .03C.
The only real difference between a .25C load / 100A and a 11.5 - 12A / .03C load is that the .25C load hits 2.800V at -425Ah's and the .03C load hits 2.800V at -441 Ah's..
If I stop the .25C load at -425 and, let the voltage rebound, then turn on the .03C load I can get -440Ah's from the bank.
So a net difference of 1 Ah and well within the margin of error.....
I could get 500Ah's at a low "C", never assume! 500Ah's was not the case but I am still performing better than the face value rating when drawing at below .5 "C" / 200A which is what the bank is rated at from Winston.
I think, for house bank use, we can take away that a .5C load would never be the load so we use on-board. If that is the case then we can expect slightly better Ah performance when drawing at well below .5C if the cells are within spec....
I suspect that a .5C load would yield 400Ah's +/- to 2.800V per cell but that if I turned it off, let the resting voltage rebound, then applied .03C I might still get the -440 +/- out of it... (this is another assumption and could easily be shown to be incorrect.)
Results of three complete capacity tests:
.25C = -425 Ah's to 2.800V
.25C to 2.800V / Rebound / Apply .03C = -440 Ah's
.03C = -441 Ah's to 2.800V
Initial capacity test 232 cycles ago: .25C = -425Ah's to 2.800V (I did not test for rebound with .03C)
In all cases I am charging CC/CV to a 13.8V pack voltage and allowing the current
to drop to about 5A before terminating charge. This gives up a tad bit of performance on the very top end, perhaps 2% but allows for a head
*Cell Voltage Monitored Using Cell Log 8S (Calibrated to Fluke)
*Cell Voltage Manually Checked With Fluke 179 (Calibrated)
*Pack Voltage Measured Using Fluke 179
*Ampere Hours Recorded Using Victron BMV-602
*.25C Loads Applied Using 2000W Inverter
and Ceramic Disc Heater
*.03C Loads Applied With Light Bulb
Hope this data helps....