Ferrites, and buzzing

[landyacht318]

Hoping to start a discussion, not solve any issue here.

I have a "watt's up" wattmeter clone from Windy Nation. This came with 8awg leads instead of the usual 12awg.

I'd found its AH and KWH figures were straight from bizzarro world when tested against other meters, and gave up on it. But it is still useful for voltage and wattage, So I put it in between the Screwy31 and the schumacher Sc2500a "intelli" charger whose display is now toast, but other wise operates as it did new.

So this wattmeter on the schumacher, the voltage and amperage readings just bounce around. At 2 amps it will bounce from 0.07 to 8.82 amps and voltage will bounce +/- 0.5 volts. Another wattmeter inline is nice and steady.

When placed between battery and load this wattmeter reads amps volts fairly accurately, but in between schumacher and battery and it goes battcrap crazy.

So I have some Snap on Ferrite cores that fit over both 8awg leads together, and after doing so, the battcrap crazy level of 10, falls to a level 7.

Eyebrow raised, but Eh, shoulder shrug. Screwy31 is charging. Voltage with Schumacher unplugged from 120vAC still accurate.


Today, I found another snap on ferrite core, slightly smaller inner diameter. I thought perhaps more ferrites would perhaps help soothe the battcrap crazy wattmeter. It would not fit over both 8 awg wattmeter wires, or both 10AWG wires coming out of Schumacher. So I go snap it over one 10awg Schumacher output wire.

And as soon as the two halves get close to each other the schumacher starts buzzing loudly, Surprisingly loud. Open core back up and noise attenuates. I can modulate the volume of the buzzing just by how closed the snap on ferrite is over either + or - output wire.

Sounds like 60Hz.

It seems like I can actually feel the ferrite vibrating in my fingers.

What The pluck is going on?

[MEXICOWANDERER]

Electrolytics are polarity marked. In decimal microfarads the caps are capacity denoted and can be connected either way. Look for a capacitor the size of a rubber pencil eraser. Make sure the leads come out the same side. And -nothing- colored blue. Connecting a varistor won't hurt it but it will play possum. When playing capacitor fire drill I use jumper leads with clips.

[landyacht318]

Ignorance is such bliss.

While not learning anything, i was happy that the schumacher would seek and hold a respectable absorption voltage for almost not quite long enough on the AGM setting to actually get the battery close to full charge. It floats at 13.6, so eventually....

Now I had to go and experiment with wattmeters and ferrites and found all is not just a 'super groovy just fine'.

I wish I had the time and gumption to get the ferrite to not buzz.

But the battery charges. it is simply the one wattmeter does not like it. I have another one which does not care.

The problem only became apparent when I tried to get the unhappy wattmeter to be happy.

But is it really a problem?

Hmmm.

So say I have various cheapowatt recycled capacitors I was willing to put on the output terminals to see if I could eliminate the ferrite buzz, and perhaps get screwy wattmeter to not jump around whack a doodle like. How do I go about finding which capacitor leads go on the + or -?

I get that new capacitors are cheap, but, I am not buying anything I do not absolutely need to at this point, and this does not even come close to that threshold.

[MEXICOWANDERER]

Choke Choke...
The key of E flat......

"Eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee"
(smoulder)
"eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee"
(smoke)
"eeeeeee............................"

I smoked a 9.5Kw 3-phase transformer by an overdose of wishful thinking. Shorted all three X secondary windings before the 10-amp breaker tripped. So much for my SCR PWM control circuit.

Put unit to work
Have caps ready to clip
Resist connecting electrolytics in reverse polarity.
Pluck your magic twanger by passing the ferrite near the wire.
If it starts to scream - try cap #2
And so on.
If you want to buffer lower freak ripple a 470uf electrolytic will help
RCL can be soooooo much fun! Resistance/ Capacitance/Inductance

[landyacht318]

It sounded like the noise was coming from the inside Schumacher, but I could feel the buzzing in my fingers as I closed the snap on ferrite.

I have the powerpole only 5 inches from the schumacher and the ferrite within that space so it is not so easy to tell exactly where the noise was coming from.

The buzzing it too loud to deal with. It is easily heard over a computer fan rated at 37dba

Snowman9000, thanks for the report on the Turnigy. I was very bummed that on a regular load the Windynation 8awg Wattmeter readings were so far adrift from the other wattmeters and my battery monitor.

It also froze up a couple times.

[MrWizard]

What was buzzing
The charger or the ferrite bead
If it was the charger remove that bead

If it was the bead don't worry about it, except for being annoyed by the buzz

[Snowman9000]

I know you are not trying to solve it, but let me add that I've seen similar behavior on the readings with my Turnigy wattmeter, when using the cheap Harbor Freight charger.

[MEXICOWANDERER]

Ah yes the world of resonant frequency and 2nd and 3rd harmonics. I tried to list capacitors in ordinal the likeliest first. Just a guess but something is whispering the noise may be in the 5-10 KHz range. It would ignore a 200uf capacitor. Do try the .01uf If it is an issue with resonance the .01 just may affect it enough to gain a clue. This is feeling my way at midnight with heavy gloves but hopefully it will get you moving forward.

[pianotuna]

Mine go over both wires--but it is coax wire.

landyacht318 wrote:
Are the ferrites supposed to go over both wires and not just one?

[landyacht318]

Wonder if any of the cheapowatt's capacitors could be recycled.

The outputs on the circuit board are basically male quick connects.

When I added 10AWG all I had to do was get new female quick connects and crimp/solder 10AWg to them and slide them over the output terminals.

The only real 'issue' is the Windynation wattmeter itself simply does not like the schumacher. I have a regular GTpower wattmeter that I modified with 8awg, and it has no issues reading correctly when put between Schumacher and battery.

As the WN wattmeter's AH and KWH readings are half of what they should be, although amps and voltage are fairly accurate, I figure it is just a POS, and was good enough for the POS Schumacher on a battery that should have shorted a cell a year ago.



I was just stunned that the ferrite on the outside of a single wire caused such a loud buzz.

The Schumacher keeps me from lugging the Screwy31 to the meanwell or the meanwell to the screwy 31, so I hope the POS holds on.

[MEXICOWANDERER]

Try attenuating with electrolytic capacitors. .01 -.1-.47-10-47 uf 50 volt are cheap. Need to go as near to the source as practical. I cheated inside the BORG with tantalum because of size/fit limits. Schmucker, really has some issues these days. I suspect everything has been outsourced and from designer to screw tightener the far east crew has never gotten near a genuine battery. Unbelievable what I've seen...gimmee a break button rectifiers pressure sandwiched between to aluminum sheet metal plates?

Try the caps and maybe you'll slide on this one.

[landyacht318]

Are the ferrites supposed to go over both wires and not just one?

The schumacher had, and I returned, A non snap on Ferrite on the output leads 3 inches from circuit board.


The larger ferrites on the both wattmeters leads did not cause any noise and are only 6 inches away from the one that causes the buzzing clamped over only one wire.

I replaced the original 12awg with 10awg to the circuit board, and use 45 amp anderson powerpoles. I did the 10 AWG mod hoping it would keep it from going to 16.4v and perhaps the display would read closer to actual voltage.

Neither improved, and now display does not say anything but 18.8 all the time. Kind of need some deisplay on the output to see if I pressed the right buttons for AGM and for 2 12 or 25 amps.

[westend]

Your Schumacher is an escapee from the Wave Form Insane Asylum. The feedback from the output is what you are modifying with the ferrites. The chopper circuit in the schizo charger is trying to power the induction from the ferrites and having a poor time of it.

[DrewE]

The charger is not producing a nice clean DC output, but rather some sort of pulsed output. This is not unusual; many battery chargers have no output filtering, and batteries basically don't care.

It would be interesting to look at the current output waveform from the charger on an oscilloscope. The voltage output is somewhat steadier since its excursions are moderated by the attached battery.