Originally Posted by monte
I think Simons monitor uses ams in and out and peukerts to calculate SOC. Otherwise SOC would jump to 100% using the theory that it resets at 12.7v. I believe our mastervolt is the same, currently showing 13V but at 90%. Of course I could be wrong!
Most battery monitors/ Ah counters /Coulomb counters do not use the amps in/out to calculate full
... They rely on an accurate reset
. If they do not reset accurately
, when full, and most DO NOT, they will snow ball and counting errors can become huge...
Most Ah/Coulomb counters reset on:
in % of "C" (usually 2% or less)
Time at % "C" current
Time at voltage
It is very, very, very easy for solar
or hydro to replicate the above "re-set" parameters. When this happens the battery monitor will reset to 100% regardless of where -Ah's are.
I have been standing there at a nav desk when a battery monitor for a 460Ah bank suddenly went from 91% SOC to 100% SOC... That can't physically happen, but the solar system made it appear
to happen to the Ah counting monitor..
These devices were designed around battery chargers and alternators that can provide a steady current and voltage in excess of the set parameters so when set parameters are attained it is usually a somewhat accurate representation of what is really happening (course far to many charge sources enter float prematurely so that involves another very long discussion on why your Ah counter may not be accurate..) .
and hydro can easily mimic "full" parameters unless the monitor is carefully calibrated and "known full" human powered resets are performed regularly. Ah coutners require human intervention to work the best they can.
At a bare minimum they also need to know:
Peukerts Constant (which is really never "constant" but the best we can do)
Battery Temperature (avg case temp or add a temp sensor if it allows)
Ah Capacity (very rare that a bank is delivering at "rated capacity")
Charge Efficiency/Coulombic efficiency
As to solar not performing panel temps reduce efficiency. The fact that on most boats the panels
are flat mounted can also affect performance. Long wire runs with small gauge wire can also eat into charging
performance. For the best charging
performance it becomes necessary to get the voltage to the battery terminals so the most current can flow into the bank..
I was on a boat earlier this year where the wire from the controller to the bank was sized for a 3% drop. Yep it had slightly more than 3% at 3.4% when I measured it.. What did that mean at the batts when the controller was pushing current? It meant that the bank was seeing 13.9V not the 14.4V the controller thought
it was regulating/limiting voltage to. On top of that this was an MPPT
controller and the wires going to the controller were also dropping precious voltage so his MPPT boost
performance was also lacking. A few wiring
tweaks and his solar performance was, and I quote, "stellar man".......
There is a lot at play here and many things that could be leading to the performance issues.. We really need more data... Nolex's test outlined above is the easiest to perform. Turn on a load larger than the solar and if solar performance does not change or improve the issue is not full batteries it is in the solar system. If the solar output goes up, you are dealing with Ah counter calibration issues.