Radio interference

[SgtPepper]

Well I've had almost one year of faultless running with my classic lite. The only thing that get's on my nerves is the interference it creates when I am listening to my am/fm radio. Is there anything I can do, short of ear plugs, to alleviate this??

[Vic]

Hi Sgt ..,

Try reading this Thread,  and also look at the Link to discussion on the wind-sun Forum noted in Reply #14,   IIRC:
http://midniteforum.com/index.php?topic=2057.0

Often, the best bang comes from locating your receive antenna outdoors,  AWAT from the PV conductors/power conductors,  and for FM,  try using a directional antenna that looks for your favorite FM stations off of the back of the directional antenna (if possible).

Also,  note that Inverters are often larger culprits than are CCs.

FWIW,  More later,   Vic

[boB]

welcome to the forum! First question is does the interference happen only during the day while the classic is running? Or does it also occur at night when the classic is resting?

does your a m f m radio have an outside antenna or is it an inside radio some were else in the house ?  or is it near by the classic and other equipment ?

[SgtPepper]

welcome to the forum! First question is does the interference happen only during the day while the classic is running? Or does it also occur at night when the classic is resting?

does your a m f m radio have an outside antenna or is it an inside radio some were else in the house ?  or is it near by the classic and other equipment ?

It happens during the day as soon as the sun hits the panels. a small amount at night too when resting, but it's bearable.

My radio is just a step up from a transistor radio with a telescopic antenna, no outside one.

[boB]

Try this during the day.

Tune to a channel that is causing interference but you can here somewhat at least...

Then, connect or disconnect the Classics' chassic ground and reconnect it and see which way, if any,
is better or worse for the radio reception of that signal.
Hopefully you have a ground connection handy and if already grounded, try this if it isn't too hard
to disconnect that ground.  Sometimes it is very hard to do because of the Classic's mounting
method to the rest of the system... For instance, when the Classic is mounted to a back-plate and
to an E-panel with a conduit makes it difficult usually.

This may help determine what EMI reduction might help.

boB

[SgtPepper]

Thanks for the help Bob, I'm away from home for ten days, but will try it when I get home. Shall I disconnect the earth at the earth rod or where the earth connects to the CC chassic?

[boB]

Disconnect right at the classic chassis.

If you had some ferrite toroids to run the input and output wires through at the classic, that would be the next trick to try, usually.

boB

[SgtPepper]

Roger that Bob, i'll let you know how I get on.

[bcroe]

I don't know what a "classic lite" is.  But a modulated pulse style charge controller generates
an on-off current in the whole panel-battery loop, which then is an antenna to radiate the
high frequencies of the pulse edges.  The first fix it a controller that greatly slows & controls
the rise & fall of the pulses, limiting high frequencies.  That costs more and increases heat some. 

Any MPPT type system uses a much higher frequency modulation, which isn't directly connected
to other equipment.  Properly filtered and shielded, radiation should be very small.

When all that fails, the offending equipment can be put in a shielded "box" which has plenty of
ventilation holes.  Screen with soldered cross points (hardware cloth) works.  Then all power wiring
is sent through FEED THROUGH style radio frequency filters mounted in the shield.  Ready made
AC line filters are available, and these can be used for DC if max voltage & current are observed. 
Bruce Roe   K9MQG

[TomW]

I don't know what a "classic lite" is. 

Bruce;

From MidniteSolars Products Page:

The Classic Lite is identical to the standard Classic except it does not have the Graphical Display, push button programming or Arc Fault protection, Instead it has dip switches for programming and LED’s for status.

The "Classic" is an MPPT charge controller, by the way.

Tom

[bcroe]

I don't know what a "classic lite" is. 

Bruce;

The "Classic" is an MPPT charge controller, by the way.   Tom 

An MPPT should be easy enough to filter, since there is no direct switching of the
input or output currents.  There will be some level of internal filtering, but apparently
not enough.  Some switchers I built took 2 layers of switching for a complete cure. 
Bruce Roe

[Vic]

Perhaps this is not exactly on target for SgtPepper's situation;

However,   Most CCs that are designed and tested to pass FCC Class B emissions often have little or no suppression devices that are (intentionally) active below 30.00 MHz.   As,  30 MHz is the low frequency limit of this test.

Suppression of EMI/RFI in the MF and HF frequency ranges is usually expensive,  and DOES  reduce efficiency (at least a bit).  And for the AM Broadcast band,  the emissions can be quite high,  even for battery-connected devices that meet FCC B.

Generally,  the largest emissions from battery connected CCs are Line-Conducted,  and by definition,  the FCC B test requires connecting an interface (LISN)  to THE AC conductors connected to the device under test (and there are none of these for most battery-charging CCs).

The experience here,  is that the PVs and the conductors connected to them are, by far,   the largest antenna for radiated emissions.   Generally the battery connections are compact and fairly short,  compared to the PVs and the cables connected to them,  and thus usually smaller emitters.

Separation of the receiving antenna from the PVs and power system,  and  from Inverter AC conductors  is often the best bang for the effort,  if  there is sufficient space for such separation.

Opinions,   FWIW,  YMMV,   so on,   Vic

[bcroe]

Perhaps this is not exactly on target for SgtPepper's situation;

However,   Most CCs that are designed and tested to pass FCC Class B emissions often have little or no suppression devices that are (intentionally) active below 30.00 MHz.   As,  30 MHz is the low frequency limit of this test.

Suppression of EMI/RFI in the MF and HF frequency ranges is usually expensive,  and DOES  reduce efficiency (at least a bit).  And for the AM Broadcast band,  the emissions can be quite high,  even for battery-connected devices that meet FCC B.

Generally,  the largest emissions from battery connected CCs are Line-Conducted,  and by definition,  the FCC B test requires connecting an interface (LISN)  to THE AC conductors connected to the device under test (and there are none of these for most battery-charging CCs).

The experience here,  is that the PVs and the conductors connected to them are, by far,   the largest antenna for radiated emissions.   Generally the battery connections are compact and fairly short,  compared to the PVs and the cables connected to them,  and thus usually smaller emitters.

Separation of the receiving antenna from the PVs and power system,  and  from Inverter AC conductors  is often the best bang for the effort,  if  there is sufficient space for such separation.

Opinions,   FWIW,  YMMV,   so on,   Vic 

After all the regs and testing, SgtPepper can't listen to his radio.  I'm telling him
how to solve the problem, if he cares to do so.  I have been doing so since my
mothers' vacuum wiped out my short wave radio in 1956. 

Sure EMI filters add some cost, so mfrs are tempted to do the legal minimum
amount.  Filters have loses, so do wires.  If the losses are in the first 2 decimal
places, it isn't designed right.  Separating wires and antennas is still going to
leave a level of noise in your AM radio.  Lately there seems to be a tendency
to accept "barely good enough", but I still carry the "best practical performance"
banner. 

If the PV wiring is the typical worst offender, start there.  The filter could be as
simple as a couple feed through capacitors rated at the voltage and current.  A
few good bypass caps might work, with the right inductor(s).  I use off the shelf
filters when possible.  Shielding will be custom. 

When my 2 inverters went on line at 15KW, I immediately checked for radio
interference.  They were very quiet, the included EMI filters were doing the job. 
If not, I would have caged them and filtered all connections, as my radio tower
is not far away.  Bruce Roe

[vtmaps]

Hi Bruce, welcome to the midnite forum.

I've read many of your posts over at solarpaneltalk, and look forward to reading some here.

--vtMaps

[boB]

Welcome Bruce ! You must be a ham, too maybe ?

Yes, filtering enough to be able to hear the radio ~shouldn't~ be too hard but it sometimes takes a bit
of trial and error of hooking up filters and grounding, etc.

We also have been working on a filter for the Kid controller.  It isn't designed for 60+ amps
but maybe we should think about one for higher current, too ?

Usually it consists of a ferrite toroid or two and a couple of capacitors, or maybe 3 or 4 caps connected as close
to the controller as possible for, mainly, common mode noise and a small amount for differential.

boB