Project Midnight Calm: How to quiet a MidNite Classic Charge Controller for $9

For the most part, I’ve been very, very happy with the solar power system I set up for my off-grid office.  Functionally, does exactly what I hoped (and rather exceeds expectations most of the time).  But I have one complaint about it: The MidNite Classic 200 is really, really noisy.  And this noise comes in a fairly distracting form at times.

This is a companion discussion topic for the original entry at

(Comments from Blogger)

2018-10-22 by xnfrmn1

How has it measured up over time? I want to add the cooling effect of another fan to extend the life of the internal fans. This seems like a great way to do it.
Thank you for posting!

2018-10-22 by Russell Graves

So far, so good! I did have to send the Classic in to get some inductors replaced (they were whining badly and driving me up the wall - 11kHz and 14.5kHz in my office is not an enjoyable whine - though they did say it was purely an annoyance, not at all a functional issue), but the fan box is working great. I almost never hear the 40mm fans anymore, and this fan is far, far quieter. It does a great job of keeping the temperatures below the 40mm setpoint, and I run it on low.

I’d fully encourage you to build something like this. I’m entirely happy with the result.