Quote:
Originally Posted by rickst29
The MOSFETs in the switches consume 1-2 Volts of output potential on the 'Load' circuits. The DC heater side, however, runs 10.7 Amps at @ 14VDC. The 2V voltage drop creates a significant loss of power on this path: At the 12 Volt net potential after 2V loss in the SSR, we will run at only 9.2A (yielding just 110 Watts, instead of 150). This is below Norcold's minimum DC voltage limit of 13.5V, so I could need to add a Buck Boost DC regulator as well.
|
Rick -
That may be overly pessimistic.
First, I seem to recall that in some thread, it was pointed out that the "spec" of 13.5 volts is a typo by Norcold, and that the real number was 11.5 volts. I'll see if I can find that comment.
EDIT: Found it. See posts 3 and 4 here
Second, my guess would be that the minimum voltage spec applies only to the voltage that operates the electronics, not the voltage applied to the heater. If the heater voltage is low, it would not get as hot, which would slow down the cooling process, and 110 watts vs 150 might be a significant hit. But I'm not sure it would affect anything else.
Please remind me why the MOSFET switches, with their 2-volt hit, can't be replaced by a relay? Or maybe a pair of relays, a small one driven by the PID, to operate the power-handling relay? I think you discussed it at one point, but I'm not finding it.
Bill