Why doesn't MidNite tout it's Part 15 Subpart B certification more?

[Gordon]

Hey Folks,

Was just wondering why MidNite doesn't make a bigger deal out of how clean it's charge controllers are? This was a major factor in my decision to buy the Classic 150 and not too many other manufacturers are making clean-running (RFI) charge controllers. It's not in the owner's manual or on the label on the unit either.

I would think that a lot of people who need an RFI-free environment would want to know this. I notice right away by how clean my electric guitar sounds when there isn't all that noise floating around in the air.

[Resthome]

Hey Folks,

Was just wondering why MidNite doesn't make a bigger deal out of how clean it's charge controllers are? This was a major factor in my decision to buy the Classic 150 and not too many other manufacturers are making clean-running (RFI) charge controllers. It's not in the owner's manual or on the label on the unit either.

I would think that a lot of people who need an RFI-free environment would want to know this. I notice right away by how clean my electric guitar sounds when there isn't all that noise floating around in the air.

It's not all that clean when charging. In particular Marine VHF channel 68 if you are anywhere close to the CC is unusable.

[Gordon]

I've had both an Outback MX-60 and the Xantrex C60 and they make some serious noise. This is the testing that I saw done by a Ham radio operator.

https://www.midnitesolar.com/pdfs/Radio-Frequency-Interference-Charge-Controller-Comparison-Report.pdf

[boB]

One of the reasons we don't tout that too much is that any Class B compliant device still makes noise. It's just a matter of degree or how much EMI and at what frequencies.  Evidently Resthome has found that his Classic even crosses one of the VHF marine frequencies.  That's a matter of luck or lack of luck because I'm sure that any birdie made up there will change in frequency with individual Classic or temperature.  It is very weak at VHF though but enough to break the squelch ?

Also, to be technically under the class B line at around 40 MHz, you need to add a common mode ferrite toroid around the battery and PV lines.  It was barely over the line without that as I remember.  Maybe 3 or 4 dB over.  But VHF and above, didn't really matter much as the EMI was much lower than the requirement.

It's not too bad though. Could be a lot worse. 

boB
K7IQ

[Resthome]

One of the reasons we don't tout that too much is that any Class B compliant device still makes noise. It's just a matter of degree or how much EMI and at what frequencies.  Evidently Resthome has found that his Classic even crosses one of the VHF marine frequencies.  That's a matter of luck or lack of luck because I'm sure that any birdie made up there will change in frequency with individual Classic or temperature.  It is very weak at VHF though but enough to break the squelch ?

Also, to be technically under the class B line at around 40 MHz, you need to add a common mode ferrite toroid around the battery and PV lines.  It was barely over the line without that as I remember.  Maybe 3 or 4 dB over.  But VHF and above, didn't really matter much as the EMI was much lower than the requirement.

It's not too bad though. Could be a lot worse. 

boB
K7IQ

boB. No ferrite toroidal and Ethernet cable connected to a one port router. Once I push off over 10-15ft from the side of the boat where the CC is mounted in side it stops breaking the squelch. Just happens the Marina uses VHF Ch 68 so my radio is set to scan that Ch.

[Gordon]

As far as interference goes, just breaking the squelch is basically very little. I'm glad to hear that's all it does.

From what Bob is saying above though, it seems that maybe the units don't really have the certification that I thought they did and they're just very close to the limit, but still a bit above the cutoff at 40 Mhz.

Anyway, really clean from and RFI standpoint, which was a major factor in my purchasing decision.

[Gordon]

I'd be curious how it does with the Ethernet cable disconnected, since that is the one condition that the guy who tested for RFI noted as being problematic.

[Resthome]

I'd be curious how it does with the Ethernet cable disconnected, since that is the one condition that the guy who tested for RFI noted as being problematic.

I think he mention if it was connected to an Ethernet switch. Mine isn't connect to a switch. But I will check that out next time I'm up there.

Yeah it's not just breaking the squelch it also produces a very loud noise and can not be squelch. Only solution is to move away.  My main VHF antenna is a good distance away an no problem with that radio.

[Vic]

Just a few cents-worth ...

IMO,  for electronic devices under FCC Part 15 (b),   which are NOT designed to be connected to the utility AC power lines,   there is no Emission limits specified,  below 30.0 mHz.   There is no measurement device specified for connection of the measuring  equipment to the device under test:
https://www.law.cornell.edu/cfr/text/47/15.107

That linked test summary may not apply very well to other situations,   as the test setup-is not well specified,   even for comparative tests.   Small differences in the setup of the cable routing/dress can make relatively large differences in measured emissions.

Not to diminish the importance of the work done by MidNite.   In a direct swap of OB MX-60s for MN Classic 150s,  with identical PV arrays,   the emissions in the HF radio spectrum  were diminished by about 4 - 6 dB,  using the same PV array,   cabling at nearly identical output current levels,  depending on many variables ( receive antenna used,   antenna location/orientation, etc. ),   and CC operating Mode,  etc.

Common-Mode chokes on both the battery and PV cables,   close to the Charge Controller  are very,   very effective in reducing emissions in the HF spectrum.   Obviously,   the emissions from these MPPT CCs are much greater at lower HF frequencies than those in the higher HF ranges.

The emission birdies are surprisingly stable,  at lower frequencies,   so often any emission birdies that do exist can often be avoided.

Of course,  once the emissions from CCs are reduced appreciably,   one can often begin to hear emissions from other power electronics,   like inverters.   But,   inverters that are designed to be connected to the power mains DO need to comply with Part 15 (b) Conducted Emissions,  which cover the frequency range from 150 kHz to 30.0 mHz.

The above are just my  opinions.   Am very happy with the MidNite Classics (and KID)  CCs,   and the MX-60  was an amazingly capable CC,  when it was first introduced,   and know of many MX-60 that are still in service  --  some have served 15,  or more years.

But,  would not trade any of the Classics here for any other CC.    Thanks MidNite!
FWIW,   Vic