Originally Posted by
rbarrow
One of the issues with using Open Circuit Voltage to determine State of Charge (SoC) on lithium iron phosphate is that they have the flattest discharge curve of all battery types, which makes it very difficult to estimate SoC on a simple voltage measurement. The voltage difference between two SoC values may be so small that it is not possible to estimate the state of charge with good precision.
I understand you are using the tools available to you but I found it unusual, based on our experiences, that you discharged your 50Ah bank in a single day to that low level unless you were in heavy current or high winds for a long period of time. Some of the LiFePo4 batteries on the market have integrated BlueTooth bms systems that measure actual current in and out. The results from the bms "gas gauge" app seems to point to a average discharge of no more than 50% on a typical fishing day using 112 Ultex. While I do not claim these are particularly accurate, they come close to mirroring my on-the-water experience.
I know ReLion is investigating a couple of approaches to bring us tools to give us a "gas gauge" but not quite here yet.