Victron 75/15 MPPT RFI Problem on HF Receiver

Hello Operators

Last week the Victron 75/15 mppt charge controller was tested for RFI. Unfortunately, the load port dumps an enormous amount of RFI on an HF receiver, while the receiver is powered by the 75/15 load port and charging with solar power. The next clip is a short video published on Instagram and YouTube showing one of the RFI tests.

Toroids arrived 21AUG2022, testing continued.

Testing the effectiveness of an FT240-31 toroid, in removing RFI from the @victron_energy 75/15 load port during solar charging. 

Test: inconclusive

Unfortunately, the clouds have rolled in, so this test will continue when the Sun returns.

Here’s what we’ve learned so far

  • The noise is generated inside the controller.
  • Adding a toroid on the PV input doesn’t help!
  • Noise is introduced to the radio on the power cable.
  • Changing the PV from portable to tower-mounted and grounded doesn’t help.
  • Very little noise via antenna!
  • The noise gets worse on lower bands.
  • Noise increases with greater current.
  • RFI stops when the battery is fully charged.
  • Without more than 7 amps current from the PV, RFI is difficult to detect on 17 meters or above.

Validate my tests

If you’d like to make your own tests with the same or similar Victron model, here are my testing perimeters.

  • The radio is connected to the load port of the Victron.
  • With the solar panel connected, be certain more than 5 amps are coming in from the solar panel
  • With the radio connected to the load port, solar panel connected and charging, test 80m, 60m 40m, 30m, 20m, 17m, & 15 meters for RFI.

Some operators report no RFI when connecting their radios directly to the battery, without using the load port on the Victron. If others can validate, this is a good thing! The only problem is losing the built in logging statistics from the load pott as well as the incoming current from our Solar panels. If we don’t use the load port, we can’t get statistics on the incoming and outgoing energy directly from the Victron.

That’s all I’ve got for now guys. Please comment with your test results in the comments below.

Julian oh8stn
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  1. Hallo Julian,
    I’m using the Victron MPPT 75/15 for many years in my shack to load different batteries. In main lead acid and lead gel batteries. I never have seen any RFI in all bands hf anf uhf. I did not load lifepo4 batteries until now. Therefore my suspect ist that the power management of your lifepo4 battery may be the source of RFI.
    vy 73

    • It’s a great point but I need to update the post. I already tested with a lead acid battery, and still have the same result. I even tested a lithium iron phosphate battery which had no battery management system. Same result.

  2. Hi Julian
    The voltage of the solarpanel should be at least 5 volts higher than
    Youre battery voltage , Maybe thats solves the problem
    I have bought me also a victron solarcharger and read in the
    Manual that it is better to have 2 panels in series ,
    Just a simpel tought from my side

    73 ph7fe harry

  3. Hi Julian
    My experience is that ANY DC/DC converter makes tons of noise with its buck regulator, it is just the matter at what switching frequency is it operating. I suggest L-C filtering at the output. You can buy them on popular sites, search for dc/dc lc filters..

    73 S55ES

  4. Julian – thanks for opening up the discussion on this. Some thoughts:

    () Generally, there are two ways that this noise gets in to our receivers: radio supply coupling and over the air.

    () The source of RFI from supplies and converters is almost always from high frequency current transients creating fields in the near-field. The solution is usually to squash these at their source to keep them from radiating and also to keep the ripple out of the radio supply.

    () As Janez points out, DC-DC switching converters are inherently generators of noise – at harmonics of their switching frequency because the waveform of the current at the power switches is a sawtooth with abrupt changes at each cycle. Heavy L-C filtering will smooth that out at the output, as will ferrite filtering (inductive choke). That needs to be done on both sides of the DC-DC converter as both sides are connected to long power lines that act as RFI radiators.

    You’ve already demonstrated that most of the problem is radiated. That means you attack the problem by keeping the noise from getting out on the air and you keep your antenna as far from the noise source as you can. Ferrite filters at all three ports of the charge controller, with the biggest ones at the highest current lines (PV and battery) should help.

    Depending on the design of the controller, the switching currents (between input cap and switches, and switches and switching inductor and output cap) might be long and unshielded. If so, the PCB itself will be radiating. If the ferrites and physical isolation are not enough, you’ll need to form a faraday cage around the unit. Copper and nickel are best… you can also source thin u-metal impregnated RFI absorbing sheets. Most practical would be a copper foil wrapper with the seams soldered. The fields created by the internals hit the absorber and get dissipated. The rest hit the copper and create eddy currents which cancel the fields which generated them.

    It takes purposeful design to create a high current switcher that is RFI quiet. High quality consumer electronics manufacturers design for this in mind, because they often have their own radios on board.

    I do have one of these Victron units buts it’s not deployed near my antenna and the radio supplies are filtered, so I haven’t noticed this problem.

    • Brian AG6WR here again… attempting to share a couple of videos I made of my own experiment with my Victron MPPT charge controller and looking on a spectrum analyzer at the resulting noise generated. Some notes:
      () I have heavy ferrite filtering on the solar side and the battery side by virtue of my station, though it’s not immediately obvious in the setup.

      () Charge rate for both experiments are relatively low — only an Amp for the first experiment and 2A for the second experiment.

      () Antenna used is not tuned for HF, nor does it need to be for this experiment. I’m looking at relative levels only.

      () Conclusions seem to support the idea that with FT140-31 cores and 6-10 wraps on the PV and battery side, the case itself is the dominant radiation point for the HF noise. Better shielding on the unit seems to help but not eliminate the measured noise, though the actual desense it causes in operation has a lot to do with proximity of the unit to your antenna and the local ambient noise level.

      () In my experiment, neither of my normal-use HF antennas could hear the noise.

      Brian, AG6WR

        • Julian – maybe. I’m limited in what I can do with the limited solar I have. Here in the Fall, I have trees covering the panels most of the day and it’s oblique angle when full sun. I was hoping this would be enough to get you to filter the PV and battery side and to show us far away the unit is from the receiving antenna.

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