Aux output based on FET temperature

[dbcollen]

Robin,
Could you use the smaller terminal blocks on the pv, and the larger ones on the battery side?

[JerryB]

Hi Robin,

Thanx for the reply. I apologize for the delay in responding; we were out on the boat for the month of July and part of August. Regarding the array size, the panels are mounted horizontally since the (azimuth) orientation of a boat is unpredictable. If you run the trig on the panel output, factor in substantial heating under full sun conditions and conversion efficiency, the amount of time the panels are actually putting out more than 1300 watts is pretty small. This is based upon perhaps five weeks of intense scrutiny via the local ap (great program!). What I wanted was a more substantial output when the sun is low and when conditions are not perfect. The (classic) ambient temperature is usually well below 25 celcius, but the case and fets get very hot as the current approaches the 97 ampere internal limit. Lacking an aux output triggered by FET temp, I arranged a case temperature sensor which activates a 6 inch external blower which dramatically lowers the FET temperature. My original point was that such an aux option should be a simple and useful "tweak" to the firmware. The "clipper" that you refer to was an attempt to harvest power during the time when the Classic cannot absorb all of the power from the array. This would occur if a) the panel output were over 1300 watts and/or b) when the battery is approaching full charge. In both cases the input voltage will increase above the nominal MPPT point. My circuit is a Pulse Width Modulated gate which applies the panel voltage to a 10 ohm load (the hot water tank heating element) beginning at about 85 volts and is full "on" at about 95 volts. It works just fine. If you feel I should isolate this load from the classic input with a diode for some reason, I can do that, but I felt the input capacitance of the Classic would smooth the waveform and thus not confuse the controller. I understand that a dead short on the input of a buck regulator would create a problem, but that's not what we have here.

The #6 wire does not feel hot, but I can and will increase its size. I can fabricate a terminal for it.....

Thanx again for the input.

Jerry

[Resthome]

The #6 wire does not feel hot, but I can and will increase its size. I can fabricate a terminal for it.....

Thanx again for the input.

Jerry

I suspect Jerry is using Marine Grade wire if the Classic is mounted in the engine room on a boat. Marine #6 is the largest size you are going to get into the battery terminal block on the Classic 150. I used the MN Mini-Buss bars to connect the Marine #6 and Marine #2 together and even the Mini-Buss bars had to have the 4 gage holes in the buss bar enlarged to get the #6 Marine wire in.