Test of accuracy
Full power battery charge
Before I send the PC boards to the board house, I wanted to determine how accurately the charger can measure the Current, Voltage, and Temperature.
250V with a 10 bit converter has ~0.2V resolution, and the current has about a 2 ma resolution. The temperature is about 0.3 degrees F resolution.
Also wanted to see how clean the signals were.
After making a few component changes I am satisfied that we have a reasonably accurate system.
Of course I could have put in a dual slope or delta sigma stand alone A/D converter with higher resolution, but that would have added more cost and complexity. This seems to be good enough to do the job.
Will finish up the PC boards with a much higher degree of confidence, and should be sending them out tomorrow afternoon.
I did a thermal test of the Maintenance charger, and saw about a 35 degree F temperature rise, so I will be installing fans in those as well as the Overnight.
The fan I will use is the Sunon MB40101V2-0000-A99.
It has maglev bearings, and is rated at 7CFM.
I ran the two chargers at full power connected to a kilawatt meter, and see that at 120VAC the Maintenance uses about 80 Watts, and the overnight was at ~ 240 Watts.