Radio volume drops when accelerating

MatrixEzgo

Radio volume drops when accelerating. Ezgo 2005 electric cart 36V. New radio newly rebuilt speed controller. As soon as I depress the pedal the radio lowers to a point I cant hear it….. as I continue to accelerate the radio builds louder to the point that it is when Im standing still.

Has anyone see this? Batteries are strong not sure whats going on. I ran the voltage through a voltage reducer 36 to 12V, then wired it to two 6 volt batteries (12v) acted the exact same way.

BGW

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crash test dummy

your drawing down the load of the battery pack at start up giving less power for reducer , which gives less power to radio .. when you get up to speed your pack load is less , then radio gets enough power and acts normal ... only cure is aux battery

Sir Nuke

wait.....you got a 36v to 12v reducer and wired it (the reducer) to two 6v batteries (12v).....well there is your problem. Your reducer is made to trun 36v into 12v.....but from you you typed, you are only supplying it with 12v....not 36v. The power for your reducer should be supplied with 36v, you should have wired it to the entire pack.....not just to two batteries. Fore as the voltage drops of just those two batteries when accelerating, the voltage goes below what it needs to run your radio.....if you were supplying the reducer with 36V from the pack and it converting it to 12v, you would have constant 12v power to your radio.

WAIT A MINUTE.....I think I misnuderstood you......sorry, when you said you wired it to two batteries....you must have been taking about the radio, not the converter....DUH. man, its just to early in the morning to be thinking this hard!

MatrixEzgo

Thank you, do you think 6 new batteries could also correct this?

JohnnieB

Another possibility is the fact that golf cart controllers emit (radiate or transmit) more electrical noise during acceleration and other periods of heavy loading.

Radios have an AGC (Automatic Gain Control) circuit that reduces the sensitivity of the RF stages (input from antenna) inversely proportional to the relative signal strength of the total RF spectrum impinging on the antenna. Therefore, while the controller is putting out a lot of RFI (Radio Frequency Interference aka electrical noise) the radio while be less sensitive to the desires signal and audio output will be less.

Try cleaning all the connections in the cart's high current circuit.

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If your sound system has a Auxiliary input such as CD or MP3, see if the same problem that occurs while using the radio input, occurs while using it.

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If your radio will tune between stations on AM, listen to the "hiss" as the controller puts out different power levels. There will be a18kHz tone the gets louder and quieter. (18kHz is the frequency of the controller's PWM)

davet

Matrix-Johnie B,man am I glad to see this thread,we are talking about RFI in another Speaker thread and I have some of the same problems on 3 differant carts with radios.One cart will lose FM stations on heavy acceleration or pulling on headlights.The other 2 just pulling on head lights,2 carts are 48v with key opp reducers,3rd is same only 36v. The 48v are alltrax and the 36 is stock.It is not voltage drop because we checked that and also went to aux battery same result,we tried antenna grounds to negitive no luck.Big question is how to protect or eliminate RFI ??Dave

JohnnieB

That is a simple question without any simple answers.

Any time you pass something resembling a square wave through a non-linear resistance, harmonics of the fundamental frequency are generated, producing a broad spectrum of electrical noise. Any time you change the material the conductor is made of, there is the potential for having a non-linear resistance.

(FWIW: A square wave is the algebraical sum of all the odd harmonics of the fundamental frequency from the fundamental frequency to infinity.)

In fact, copper washers with one side oxidized, were stacked together to form some of the metal rectifiers used in the early years of electronics, and are still used today is some very specific applications where silicone diode fail to work properly (IE: In intense nuclear radiation fields).

If the copper lugs on your cables are corroded, you may have non-linear resistances throughout your high current circuit and the output of the controller is pulsed DC, which resembles a square wave, so you may have what is effectively a radio jamming system.

DC to DC voltage reducers are also RFI sources, but to a lesser extent because the current they draw form the battery pack is far less. However, it is still pulsed DC. (They are "Switching power supplies", so the wave-shape on the power they draw, resembles a square wave)

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Code of Federal Regulations, Title 47, Part 15 (47 CFR 15) requires controller and voltage reducer manufacturers meet specific EMC (Electromagnetic Compatibility) standards to market their products within the United States, but that is for the device itself and the testing is done under ideal conditions. When connected to a power source that is less than ideal, the spurious radiation can be orders of magnitude higher.

Short of putting the Controller, battery pack, motor and cables and/or voltage reducer, in a Faraday Cage (Screen Room), about the only thing that can be done is make sure all connections are tight and corrosion free.

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Of course, using a Marine type external antenna located as far away from the controller, battery pack and motor as physically possible, may help.

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If the audio system also doesn't work when using something other than a radio as the audio source, the interference may be coming through the power lines, and power line filtering may help.

greg-g

Jonnie and davet

you are close but there is a lot going on here

1st ground is good but you need a ground plane usually the car body all metal the antenna picks up signal from this reflective surface something like a parabolic dish .

2nd I think some radios do have gain control (not AGC) but use the output of the alternator to judge the speed of the vehicle the volume gets louder as the car speeds up to wash out road noise open windows the alternator puts out more voltage as you speed up. (just the opposite of a golf cart)

now on lots of radios there is a knob around the volume control that controls this gain or output of the radio so as not to have gain or more gain when speeding up.

you are correct about RFI, filters are your friend! the two six volt batteries should have helped or stopped this if they were large enough.

there is more this should give you a start

JohnnieB

1. For starters, you spelled Johnnie wrong.

2. I am a wee bit more than close when it concerns RFI.
I used to track down RFI sources and do Tempest Testing so I do have a modicum of subject knowledge and hands-on experience, but you are correct that there is a lot going on. However, where "here" is depends on whose cart because each situation is, or may be, different. IE: The noise source and transmission method can be different, so the corrective measures will be different.

3. The radio antenna often used on a golf cart is a vertical half-dipole and as such it needs a counterpoise to be efficient. Otherwise it is simply a long-wire type antenna that happens to be relatively short and won't pick up much on anything except nearby emitters.

Antennae designed to be mounted on nonmetallic surfaces such as fiberglass boats/cars and the like, have a built in counterpoise.

Grounding is not necessarily good. Or at least grounding the antenna to the negative terminal of the battery pack isn't because the battery pack may be part of the RFI source as well as creating some electrical safety issues and there is the possibility of a ground loop, since the coax shield to the antenna may already be connected to the negative terminal via the power cable. (Depends on the radio design)

On the other hand, grounding the antenna to the frame may have some effect, but lacking significant horizontal surface, the shape of a golf cart frame makes a poor counterpoise. Plus the electrical distance between the cart frame and the antenna's vertical monopole may be more than a quarter wavelength away in the AM broadcast bands, reducing the efficiency rather than enhancing it.

4. An effective AVC (Automatic Volume Control) would have to be based on vehicle speed or ambient noise level of the passenger compartment rather than alternator speed (engine speed), or the radio would be going up and down in volume as the car shifted through the gears.

Back in the 60's, I built one using a microphone under the dash to pick up the ambient sound level. Only problem with it was when parked in some secluded spot with the radio turned down low, the volume would increase when you started whispering sweet nothings.

5. Batteries do make good power supply filters, but have no effect if the RFI is airborne.

6. You are correct again, there is more, a lot more. Volumes have been written on the subject.

crash test dummy

MY BRAIN HURTS !!!