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Old 13-02-2008, 21:19   #16
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One soution I have heard is to seperate your banks in two with the inverter running off of one of the banks, if you need to use the inverter you have to flip to that bank, otherwise you use the first bank. Think I read this in Nigel Calder's book. Pain in the butt IMHO. I have the same issue with the my charger/inverter.

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Old 14-02-2008, 01:05   #17
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The issue is the smoothing of the ripple from the charger supply. Rick has sent me a humungous capacitor that I am going to connect to the line tomorrow. Wow, this will make the lights dim when she energises. Plus a choke to fit into the AC line which should greatly reduce the Triac switching noise.
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Old 20-07-2009, 22:33   #18
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Sorry for reviving such a LONG DEAD thread - Alan, what was the final outcome? Did you find a simple/stable resolution?

While initially I thought only the VHF at the nav station was affected in my case (see my previous post), in fact it happens on the cockpit VHF too, I just didn't notice it initially when I replied, and I never updated the thread (to be fair, it's worse at the nav VHF (older, not so great) than at the cockpit one (newer, nicer). I don't think I mentioned SSB in my post, but it's there too...

In my case, it happens if the charger is in 'charge' mode, whether it's shore power or using the on-board generator. Noise in the Xantrex Freedom charger I believe, and probably NOT a grounding issue between AC and DC. A ferrite on the VHF's power did nothing.
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Old 21-12-2009, 23:35   #19
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Freedom 30 noise

For five years my electircal system operated flawlessly. Recently I began to hear noise (AC hum) in my VHF and AM/FM radios when charging my batteries with the Freedom 30. It occurs only when charging, whether from shore power or from onboard genset. I disconnected the freedom and put another charger into the system hooked up with the same wires used for AC input and DC output to the Freedom 30, and the noise disappeared. I did some other tests to isolate the source of the noise and was convinced it came from AC pollution of the DC output in the charger itself. I sent the Freedom 30 to an authorized Xantrex repair facility, paid them almost $500 for the replacement of a circuit board, and was assured by them that they put an oscilloscope on the output of the charger and that it was clean DC.
Reinstallation of the Freedom 30 left me where I was in the beginning - still with the noise - but $500 poorer.
During a long conversation with the repair facility today, I was actually referred to this site and this thread. I read all the replies in the thread but did not find any specific help. Surely there is a marine electrician out there who can shed more light on this issue. I have been trying to get a marine electrician to come to my boat and help me sort out the problem - paying them their hourly rate of course - but so far 2 have expressed a willingness to do so, and then have not shown up. Near my wits end.
I may simply have to do what I have been doing. Charge my batteries with the engine alternator during times I think I might need the VHF - which of course means anytime I am on the boat. But that leaves me with the worry that the AC pollution in my DC may be causing harm to something I do not know about - like my electronic instruments and even the batteries which I just replaced for another $600.
I did talk to technical support at Xantrex and they were useless. Perhaps some of you have found a solution, or at least can point a direction.
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Old 22-12-2009, 00:00   #20
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I think the general problem is that the filters in the Xantrex charger and the radios degrade with age. I had some hum on my VHF signal from the adler-barbour refrigerator--rewiring it straight to the starting battery helped a lot, and replacing the radio eliminated the problem.
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Old 22-12-2009, 10:04   #21
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Daedulusk, don has a point. Many times the filters are capacitors, and they often degrade and fail as they age. Even when they are coils or inductors, they may degrade as they age. (Less likely but still possible.)

The primary question is are you dead certain that nothing changed? You didn't add any wiring, any equipment, change a light bulb (G) or anything that might have created a new noise souce or path? And this noise has just been building up over time?

Electrical noise on a boat will be of two types, radiated noise, or direct noise carried in the wiring. It sounds like Xantrex performed an expensive board swap, possibly instead of replacing aged capacitors on that board, or possibly just because that's what their procedure manual said to do. And if they say they used a scope to confirm there is no AC coming out of the outputs--that would only confirm there is no direct noise being put onto the power lines, it would not affect the larger issue of RFI/EMI being broadcast by the supply and getting into other things like the VHF.

One of the ways to go hunting for an RFI/EMI source is to take a plain cheap "transistor" radio, the $10 AM kind, and tune it to receive the noise signal as loudly as you can. You can also use a handheld VHF for this, since you are getting noise on VHF. Tune for the loudest noise--and then take off the antenna if you can. Then start using it like a metal detector, waving it around wires, harnesses, and the invertor, and see where the noise peaks again. If it keeps coming from the charger, I'd call Xantrex direct and say "Your dealer didn't fix my charger".

The good news is, the contractors (of all kinds, boat or home) who don't show up on time and can't call ahead to let you know about it? They're usually sloppy guys who you are better off not having do the job in the first place.

Tracking down noise and intereference sources is half art half science, requires a great deal of patience, but IS something you can probably do yourself.
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Old 25-12-2009, 19:38   #22
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Add another boat with a Freedom 20 charger inverter, and serious "hum" on M802 receive and transmit signal when in charge mode. When I get the boat back to the US I'll get to work on this problem myself.
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Old 29-12-2009, 20:17   #23
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Freedom 30 Charger Noise

I have written previously on this thread, but have had a new development. I had sent my freedom 30 to an authorized repair facility in Orlando. Since my presenting problem was the ac buzz in my VHF radio during charging, I asked them specifically to put an oscilloscope on both the inverter and charger output.

When I received the unit back (along with the $500.00 repair bill) and reinstalled it, the ac buzz was still there. A lengthy conversation with the repair facility followed and they again said absolutely that there was no ac contamination of the charger output.

Today I paid an ABYC certified marine electrician to check out my wiring system. He found absolutely no faults in the wiring system/ground system/shore power/genset setup.

But he did find one thing! Using an ac volt meter on the dc charger output terminals, he found an ac voltage that ramped up to .5 volts as the charging rate increased to only 15 amps. He checked to see what frequency the ac was, and found a reading in the 400's, which could be a harmonic of the 60 cycle current.

I had previously done this voltage test myself, but discounted the reading as false. He says it is not false, but indicated ac leakage into the dc system from within the Freedom 30.

Tomorrow I am going to remove the Freedom 30 from my boat and have a local bench technician put an oscilloscope on it. If it shows what my electrician says it will show, my next step is a $500 argument with the original repair facility.
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Old 30-12-2009, 17:13   #24
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Freedom 30 nnoise plot thickens

Now they admit it! After confronting the Xantrex repair facility with the determination by my marine electrician that there was ac voltage on the dc output terminals of my Freedom 30 inverter/charger, they admit that they never used an oscilloscope to test it.

Further they claim that the "ripple ac current" is normal, and that, as the charging current ramps up, it can exceed the 0.5 volts ac I measured.

Even further, I telephoned Xantrex technical support, and a Mr. Florante Barona told me that same thing! He e-mailed a "proposed" cure. I have attached his e-mail to this.

For what it is worth, something stinks here, and I think it is Xantrex. I am going to try to get to their engineering department and see what is really going on. But that probably will not happen. Maybe West Marine can help me get to them because they sell a lot of the Freedom units.

Whatever............
Attached Files
File Type: doc Zantrex Technical Support.doc (21.5 KB, 387 views)
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Old 30-12-2009, 17:40   #25
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Ripple current is neither normal nor abnormal. Rather, it is one factor that proper engineering and design provide for and either allow or limit.

There's always a way to lower ripple current, the question is whether someone is going to say "that's good enough" or spend more money on the product to reduce it.

Obviously, if there's enough ripple current to interfere with "normal" marine operations, someone might say that's not good enough for a product sold to the marine market. "D'OH!"

Some 12volt DC power supplies, sold for use with radios, are designed with a frequency control that allows the frequency in the switching circuit to be shifted up/down somewhat, so that any RFI which is produced can be shifted away from the frequencies the radio is being used on. So one consideration that some engineer should have had, was whether this power supply could just be retuned to shift the interference away from VHF frequencies. Might still be a problem with SSB, but at least the more common VHF should be able to get a clear window.

I would suggest that if Xantrex considers that amount of ripple, producing that amount of buzz, to be normal, then they should refund your "repair" charge AND supply you with the components to make the unit suitable for the intended use. Inductors and capacitors aren't all that expensive in the bigger picture of things, and noise filtering isn't a black art, it is an engineering and (ahem) accounting decision.
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Old 30-12-2009, 22:35   #26
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The note from Xantrex was about inverter noise, not charger ripple.


The morning VHF net in Trinidad starts by asking everyone to turn of chargers, inverters, and refrigerators in the interest of clear communications....
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Old 03-06-2010, 22:15   #27
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I'm about to go to the boat with a 91,000 mFd capacitor and an oscilloscope. I'm hoping that by placing the capacitor across the high current battery leads at the Freedom 20, I can damp the ripple which infects my electronics when in battery charge mode. I'll try to document the results with the oscilloscope and report back here.

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Old 04-06-2010, 16:05   #28
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That might very well do it. I've got a kilowatt power supply that has a nice pair of one farad (each) caps mounted in it to clamp any ripple. Power light stays on quite a while after the switch is off, but there's no ripple. :-)
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Old 08-06-2010, 20:14   #29
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With the Freedom 20 in charge mode and putting 70 amps into the house bank, my oscilloscope showed spikes of 2.2 volts p-p and .36 volts rms on top of the DC charge voltage, occurring at a 120 Hz rate.

Putting the 91,000 mFd capacitor in parallel to the charger output dropped the AC component by about 35%, and reduced audible 'buzz' in some of the electronics somewhat, but not as much as I had hoped. Below is a picture of the scope screen capture before the addition of the capacitor. I can't imagine that this charger is actually functioning to specs....

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Old 09-06-2010, 13:59   #30
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I'd call a 2.2VDC spike on a 14.4VDC line unacceptable. Have you asked Freedom what they think about it?
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