Adding Vents to the Classic 150

[Matrix]

... if you had the system in cooled space it would also keep your controls and battery cool too.   

Larry

I did today add 2 additional 18"x2" vents to my battery box on the top for a total of 4.  I already had one such vent at the bottom back as well,  but it was backed against the wall with about a 3" gap.

So today I also, cut a 4" hole in the lower back of the battery box and added a 4" toilet drain top to 4" PVC pipe 18" long that now draws from under my house.   I know that temps under the house are way cooler in the summer and warmer in the winter than outside air.  So I am hoping this is a double win for both summer and winter battery temps.

I also have the option to close any or all of these now 6 vents. 

We will see how the battery do the next warm day I charge.  But already,  with the install of the underhouse vent,  I can feel a draft in the box. 

[Matrix]

FET, Classic Cooling and Venting the Battery box update:

Finally got some warmish weather today.   80*F hi out side.

- 15x8 heatsink installed behind classic.  Found aluminum sheet metal to cut for shims for a more "full contact" connection with the sink
- 4" fan on the mid right of the CC that comes on when AUX 1 Waste Not Hi comes on.   
- Doubled my Battery box vent on the top and added a 4" PVC pipe into the box at the bottom from under the house

Max Results and Temps today:
- Generated 10.5 kWh for the loads / dump loads and 24v battery bank
- Batteries got fully charged up to 1.286 SG in the lowest cell
-Heated the water in my 40 gallon water heater to 165*F
- FETs never went above 60.7*C  (down from almost 70*C last time temps where this hi).   60.7*C was highest,  but that temp only hit there 2 times thru the later part of the day and only for about 1 hour total.  The average for the day once charging began was probably more like 56*C
- Battery temps Max inside the closed box never went above 28*C and again that was only for an hour at the end of the day.  So down about 4*C.   

Overall happy.   And probably about the best it will be unless I AC the control room. 

Battery Box vents attached:

[Matrix]

Just as a point of reference,   what should the Temp of the FETs be of a MidNite Classic at Rest?

- The sun went down over 4 hours ago
- CC is Resting: 4 Input voltage lower than battery voltage
- Outside temp is 68*F
- Control room is 73*F
- Battery Temp is 79*F
- Input voltage is 11v DC
- Battery Volts are 25.4v
- Discharge Amps range between 1-10 amps 24v DC


FET Temp = 46.4*C / 115.5*F

They never seem to get any much cooler than that, regardless of room temp.   Is the FET supposed to stay that warm all the time? 

[mike90045]

Yep. I've noticed the same thing.  Even pre dawn, that classic is sucking some watts to heat the boards and fets on the heatsink that warm.