A Kill-A-Watt EZ was used to measure the power consumption of different combinations of ceramic strips energized with 120VAC.
Then, while keeping the fan connected to 120 VAC, the 144 V battery pack -- along with the PakTrakr -- was used to measure the power consumption of different combinations of ceramic strips energized with 151-146 VDC from the battery pack.
It's interesting to note that under both test conditions, the initial power consumption of the ceramic strips was much higher when cold and as the element warmed up the power consumption dropped considerably. For example: Initially powering up all 4 strips at 120 VAC would draw more than 2500 watts and then after a few seconds it would drop down to 1566 watts. Note: The unit is only rated at 1500 watts.
Current and power readings were only taken after the power consuption "leveled off." Results are as follows:
|Two inside stips||7.3||871|
|All four strips||13.1||1550||
|Two inside stips||6.8||1013|
|All four strips||13.3||1937|
*Average of several test for a general single element reading.|
**Variations in pack voltage were recorded and taken into consideration.
For anyone that cares, the AC readings are in RMS (effective values).
The ceramic stips did not appear to be identical and the more strips that were energized during a test would cause the average power consumption per strip to be less. Most likely because more energized strips caused the overall temperature of the element to increase -- fan speed unchanged -- dropping the power consumption per strip.
While my test equipment was not really precision, it seems that this heater unit will behave quite well with a 144 VDC battery pack and a DC relay rated at a minimum of 15A. Two 10A relays could be used to have high and low (1000W - 2000W) power settings.
It can also be assumed that as the blower speed increased the power consumption of the element will increase due to lower element temperature.