Rogue MPPT, 490W and charging mysteries
Now that we were finally all in one place - me, Rogue 3048 and my rig - it was time to have some fun. 1)Battery: old starter, tested beyond dead, plates above the water. No wonder, 8 months in Mex...
Forum Discussion
Almot wrote:
Float set up 13.6.
22C, Float=13.69 on multimeter on the battery. Ideally should be 13.69. Rogue display reads 13.8.
23.5C - fluctuating 23-24C, Float fluctuates 13.64-13.65. Ideally should be 13.645. Rogue reads 13.7.
25C, Float=13.63. Ideally should be 13.6. Rogue reads 13.7.
Best to disconnect the temp sensor when you do the VTRIM adjustment, so you can eliminate any fluctuation in voltage due to changes in temperature. That way, when you have the float setpoint at 13.6v, you know to be looking for 13.6v at the battery when adjusting VTRIM.
The controller's actual voltage measurement resolution is (at best) 0.025v, and the display's resolution is 0.1v, so it's certainly possible that a 0.030v increase in voltage, for example, could cause the display to read a tenth of a volt higher. All of this is done digitally, and there's only so much that can be done to scale a 100+ volt signal down to the 3.3v max that the analog-digital converter operates on, and maintain excellent precision...especially when there's noise that has to be filtered, etc. At least within the cost constraints of these kinds of products.
The same can also be said about multimeters, so unless you have a known-calibrated meter, it's also possible that the DMM is compounding the measurement error a little.
