Alternator feedback?

[FourWinnsLC]

I'm told I am getting alternator feedback through my speakers. We unplugged the RCA cables from the Amp and it obviously stopped. The feedback gets louder when you throttle up the engine.

I'm told that the longer the ground cables are the more feedback I will get, but the radio worked just fine last year and this until now?

I always had feedback when you either turned the batteries on or off.

Is there anything thing I can do to fix this? Let me know if you need anymore information.

 

[UncleWillie]

Re: Alternator feedback?

... The feedback gets louder when you throttle up the engine...

What does this sound like? A Whine, Squeal, Buzz?

Are you talking about a whine that changes pitch is sync with the RPMs?
Or a feedback squeal like when a microphone gets too close to the speakers?

 

[jhebert]

Re: Alternator feedback?

I'm told I am getting alternator feedback through my speakers...

It is probably alternator whine due to common mode noise in the power supplied to the amplifier. Filter the power lines.

 

[FourWinnsLC]

Re: Alternator feedback?

What does this sound like? A Whine, Squeal, Buzz?

Are you talking about a whine that changes pitch is sync with the RPMs?
Or a feedback squeal like when a microphone gets too close to the speakers?

It's defiantly a whine, and is in sync with the RPM's.

The buzz comes when you turn the batteries on and off but goes away in a second or two.

 

[FourWinnsLC]

Re: Alternator feedback?

I'm not the best with electronics, if I go to a ABC warehouse and ask for filters they could hook me up?

 

[KD4UPL]

Re: Alternator feedback?

It's not feedback. It's alternator whine. Powerline filters should help. You can get them at car stereo stores, possibly Radio Shack, and online. You may have some bad or corroded ground connections. You may have a ground in one of your pre-amp cables that has gone bad.
If you heard alternator whine and turned your batteries off that must mean the engine was running when you turned your batteries off. If you really did this you quite possibly fried your alternator. They should never be run with no batteries connected.

 

[UncleWillie]

Re: Alternator feedback?

There is No reason to buy power filters for any modern boat.
The radio should be able to filter any ripple present in the DC power system.
The alternator outputs rectified DC and the battery acts like the best filter in the world.
Unless the battery is not connected, the ripple from the alternator will never make it to the Radio.

If you switch between batteries while running, always which #1>Both>#2 and never #1>OFF>#2.
The instant you switch through the OFF Position, the alternator looses regulation. The Rectifiers may Fail.
If the Rectifiers have Failed, the alternator may now be delivering 12v AC instead of DC. The Battery will not filter that out!
Also the Battery is no longer being Charged.

With the engine running and the whine in the radio, measure your 12volt power. It should be well above 13.5 volts. (<14v)
If it isn't, fix the DC Power issue first. Alternator whine hasn't been heard in a radio since Radios had Tubes.

There is a difference between the two end of the wire between the alternator and the battery.
Be sure you are getting the 12v to the radio directly from the battery, not the alternator.
If you taped into the 12 power anywhere else, Whine is possible.

 

[bruceb58]

Re: Alternator feedback?

It could also be an alternator with a blown diode that can cause this. if you have just one blown diode, the alternator could create a ton of AC ripple. Measure the battery voltage with your meter on AC and report what you get. Should be way less than 100mV.

I always had feedback when you either turned the batteries on or off.

Please explain what you did here.

 

[FourWinnsLC]

Re: Alternator feedback?

There is No reason to buy power filters for any modern boat.
The radio should be able to filter any ripple present in the DC power system.
The alternator outputs rectified DC and the battery acts like the best filter in the world.
Unless the battery is not connected, the ripple from the alternator will never make it to the Radio.

If you switch between batteries while running, always which #1>Both>#2 and never #1>OFF>#2.
The instant you switch through the OFF Position, the alternator looses regulation. The Rectifiers may Fail.
If the Rectifiers have Failed, the alternator may now be delivering 12v AC instead of DC. The Battery will not filter that out!
Also the Battery is no longer being Charged.

With the engine running and the whine in the radio, measure your 12volt power. It should be well above 13.5 volts. (<14v)
If it isn't, fix the DC Power issue first. Alternator whine hasn't been heard in a radio since Radios had Tubes.

There is a difference between the two end of the wire between the alternator and the battery.
Be sure you are getting the 12v to the radio directly from the battery, not the alternator.
If you taped into the 12 power anywhere else, Whine is possible.

I will be checking 12volt power with the engine running, unfortunately my meter is at work and I am on Vacation

A vacation on the boat with no radio lol.

Also when I do switch the batteries I always do it like you said. 1-both-2

As for not buying filters, I should of mentioned that I installed this radio last year and I have a long run of wire, and I was told just for the fact of a long run that I may need the filters? What is your opinion?

I wired the the radio, and the amp directly to Battery #2, ..... Battery number 2 is actually 2 batteries in parallel. Battery number 1 is one battery.

The first thing I did was check all connections for corrosion and emery clothed all connections, and it did not fix it.

Thank you for your input I learned a lot.

 

[FourWinnsLC]

Re: Alternator feedback?

It could also be an alternator with a blown diode that can cause this. if you have just one blown diode, the alternator could create a ton of AC ripple. Measure the battery voltage with your meter on AC and report what you get. Should be way less than 100mV.

Please explain what you did here.

Its always buzzed when you turn the batteries off for the day, Engine off.... then batteries off
Just recently it has started to get alternator whine all the time.

I will have to wait until I get my meter back to check the AC output

If a diode is bad, will the alternator still work? Charge the battery? I just completed a 10 hour trip and had no issues with power/batteries.

Thanks for all the help.

 

[FourWinnsLC]

Re: Alternator feedback?

Just to give all details
I just installed a three bank battery Tender.

I bought the Pro Mariner (Cabela's brand)

 

[bruceb58]

Re: Alternator feedback?

If a diode is bad, will the alternator still work? Charge the battery? I just completed a 10 hour trip and had no issues with power/batteries.

Yes. You will have reduced output but it will still charge.

I still want to know what you meant when you said you had whine with the battery off.

 

[FourWinnsLC]

Re: Alternator feedback?

Yes. You will have reduced output but it will still charge.

I still want to know what you meant when you said you had whine with the battery off.

I must of misspoke , I meant buzzing when turning the batteries off, it last about 3-5 sec.

Boat off, turn batteries off.

 

[UncleWillie]

Re: Alternator feedback?

I must of misspoke , I meant buzzing when turning the batteries off, it lasts about 3-5 sec.

Boat off, turn batteries off.

Can we assume you do not turn OFF the Radio and the Amp before switching OFF the Batteries.
And WHY are you switching the batteries OFF?

 

[bruceb58]

Re: Alternator feedback?

Can we assume you do not turn OFF the Radio and the Amp before switching OFF the Batteries.
And WHY are you switching the batteries OFF?

Not sure what the issue is. Amps are always powered. The radio sends a signal to turn the amp on.

Why wouldn't you turn the battery switch off?

 

[FourWinnsLC]

Re: Alternator feedback?

Not sure what the issue is. Amps are always powered. The radio sends a signal to turn the amp on.

Why wouldn't you turn the battery switch off?

I'm with Bruce on this one
This boat does not have a ship to shore.
It is trailered to the water and home every
Everyone I know turns the batteries off at the end of the day.

As far as not turning the radio off, you can assume correct I do not turn it off.
But I will start turning it off if it stops the Buzzing.

Thanks again for the information it all helps.

 

[UncleWillie]

Re: Alternator feedback?

Not sure what the issue is. Amps are always powered. The radio sends a signal to turn the amp on.

Why wouldn't you turn the battery switch off?

Just asking!
So if the radio is powered OFF the AMP powers down also, and it is just a habit to switch the battery OFF.

My boat spends most of its life on a trailer on the side of my house also.
I turn everything OFF including the Radios, but have never switched the Battery OFF.
I need to pull out a rear seat to access the switch,
it is not that this is such a big chore, but I see no advantage for the effort.
The battery survives just fine for weeks on end. We are still waiting for the rain to quit in the East!

The Tall Ships are in Cleveland this weekend. I just may brave lake Erie in the Rain!