Weird Issue with popping system?

[ac19189]

So I am running an aftermarket deck with two tens on a 600 watt amp. It works great no issues no popping or anything but I just had a light bar put in at a shop. The issue I am having is everything works like it should work but when I turn off the light bar I get a pop from my system I understand why the system volume jumps but I don't get why I have a pop the installer said the popping was normal considering the amount of power the bar is drawing but I just want advice to make sure that's the case.

The light bar is a 54" bar rigid its drawing 36 amps at around 1000 watts. It is wired directly into the battery on the hot side the ground is to the pillar of the truck. The amp for the subs is ran on a zero gauge wire from hot back to a distribution block where it has a short run to the amp then the grounding for that amp is also running zero gauge wire to the rear body of the truck cab to a distribution block as well. To answer it before people as I am planning on adding in more amp's the blocks seemed the less of a pain route.

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[huberoy123 10+ year member]

The installer is probably correct, as to why you are getting the popping sound. However, there should be a fix. Call another stereo installer and explain your symptoms. They may have a solution to your problem. Then, take it back to your installer and tell him how to fix it.

 

[ac19189]

I haven't been able to find many places open sadly. The shop I took it to was open because he also does work for the local PD installing radios and lights so on. However I would imagine that someone knows how to fix this. I imagine its due to a drop in the amp load on the battery I thought maybe switching from the AGM battery to a Lithium might solve it or maybe a capacitor for the radio itself to help keep a more stable load going to the amp but I am really guessing here I don't have the background some people have when it comes to this stuff.

 

[huberoy123 10+ year member]

Try talking to a car stereo installation tech at Best Buy. They often deal with the pop issue on some car stereo installs. Also contact Crutchfield.com. They provide great customer service, and may be able to guide you. Good Luck.

 

[Louisiana_CRX 5,000+ posts]

You could try adding a car Audio capacitor to the hot lead of the light bar that way when you turn it off it will be a gradual loss of power instead of strong burst of power loss... there will be a minor delay when switching it on as well due to capacitor recharging .. but actually light bulbs are used to charge up a capacitor when using them anyway ..

 

[Lasherž]

In this case you're trying to prevent a power spike rather than a sudden power loss. The pop is happening due to a voltage drop disappearing. Capacitors are usually thought of to reduce voltage drops, but they also reduce transient spikes. Depending on where the pop originates (amp or head unit) I'd put the capacitor in parallel with the terminals of that device. Alternatively you could put it in parallel before the switch on the light.

If you want to get a more dramatic result from less capacitance you could also use a transient clamping device like a crowbar which acts like a zenner diode to divert voltage to a capacitor when it gets above a certain threshold. They make premade devices meant to go on 12V wiring for this very problem that use the crowbar latching method because it requires less capacitance for the same result, it just doesn't help stability for drops, only spikes.

 

[ac19189]

In this case you're trying to prevent a power spike rather than a sudden power loss. The pop is happening due to a voltage drop disappearing. Capacitors are usually thought of to reduce voltage drops, but they also reduce transient spikes. Depending on where the pop originates (amp or head unit) I'd put the capacitor in parallel with the terminals of that device. Alternatively you could put it in parallel before the switch on the light.

If you want to get a more dramatic result from less capacitance you could also use a transient clamping device like a crowbar which acts like a zenner diode to divert voltage to a capacitor when it gets above a certain threshold. They make premade devices meant to go on 12V wiring for this very problem that use the crowbar latching method because it requires less capacitance for the same result, it just doesn't help stability for drops, only spikes.

Solid info this was what I was looking for just wasn't sure what route I needed I didn't think a cap wouldn't really have the desired effect I wanted it's just meant for huge spikes in draw doesn't really help the flow of it. What option would you go with I thought about it and a diode made more sense to me but not sure where would be best place to put one. Never heard of a crowbar latching gonna need to look into it I think my spoke is due to a spike not a drop. Going from like 40+ amps and dropping to 10 amps or less is causing a massive spike and I don't want it to destroy any of my gear.

Could you maybe link me to a device that uses that latching you mentioned.

 

[Lasherž]

Some interesting reading on the circuit basics.

12V 12A resettable crowbar circuit

The idea is to protect the input stage of a control card from improper power supply connection. The power supply is a standard desktop AC-DC power adapter (Meanwell GST160A12) with inbuilt shortcut,

electronics.stackexchange.com

So one that I found is https://www.littelfuse.com/~/media/...utomotive_tvs_diodes_application_note.pdf.pdf

I think the best course of action before deciding on one is to figure out how big that spike actually is though. If you're experiencing a pop from only 2 volt difference then these devices will be a current draw on your car constantly. If however the spike is like 10v then you'll start to be able to find devices like the one I linked which will clamp that without affecting normal operation. The spikes are caused by the alternator adjusting its pull, so it's quick to adjust but will never be instant enough without some mitigation.

Large spike go for a circuit protector, small spike go with a paralleled capacitor.

 

[Lasherž]

I didn't think a cap wouldn't really have the desired effect I wanted it's just meant for huge spikes in draw doesn't really help the flow of it.

Don't forget, capacitors for cars are usually 15-16v in capacity and when they charge they draw huge amounts of current. Think of a voltage spike as a charge for the cap. Capacitors resist changes in voltage while coils resist change in amperage, spikes and dips are rounded off equally.

 

[ac19189]

Tonight something happened that makes me think its overvoltage even more I turned on the light bar while the truck was off and when I turned on the truck when my deck came on even though it was really low volume I had MASSIVE and I mean MASSIVE distortion it was like someone turned the volume way up past what the speakers could run at while the deck was at a really low volume I am talking like 5 or 10 which is near a whisper level.

It sounded like the audio was playing with the mic in someones mouth I shut off the car and turned off the deck and everything went back to normal but I don't know why it would have done that even with the light off.. I turned it on before this all happened maybe the relay for the light bar was sticking? But if that was the case I could have seen light coming from the bar so I dont know...

 

[Lasherž]

Tonight something happened that makes me think its overvoltage even more I turned on the light bar while the truck was off and when I turned on the truck when my deck came on even though it was really low volume I had MASSIVE and I mean MASSIVE distortion it was like someone turned the volume way up past what the speakers could run at while the deck was at a really low volume I am talking like 5 or 10 which is near a whisper level.

It sounded like the audio was playing with the mic in someones mouth I shut off the car and turned off the deck and everything went back to normal but I don't know why it would have done that even with the light off.. I turned it on before this all happened maybe the relay for the light bar was sticking? But if that was the case I could have seen light coming from the bar so I dont know...

Yeah man, that sounds like the light bar may be a bit too much for your battery. If it's as many amps as you say it is I have no doubt it'll cause enormous voltage drops. Car amps draw huge currents too, but not constantly like that light bar. I'd never use it when the car is off, but I'm curious just how big of a drop you're experiencing. If it's too much then you may not need the cap, it may be more prudent to just go right to a second battery or at the very least an AGM. I'm betting your alternator is damn near maxed out when the bar is going, so I'm not surprised there's a little whiplash when the load suddenly disappears.

My head unit used to malfunction at like 10v, so that's a pretty crazy amount of drop. The second battery wouldn't help a ton with your spike issue when you turn the bar off, but it will affect it so I don't think there's any point in trying to address that before the voltage drop problem.

Another thing I just thought of is if the cabling for the light bar or the relay is too close to an RCA it could cause that pop as well. The relay is a solenoid magnet so it's going to affect an RCA signal through any shielding when it switches on and off and the cable going to the light bar is also generating a small EMF.

 

[Louisiana_CRX 5,000+ posts]

In this case you're trying to prevent a power spike rather than a sudden power loss. The pop is happening due to a voltage drop disappearing. Capacitors are usually thought of to reduce voltage drops, but they also reduce transient spikes. Depending on where the pop originates (amp or head unit) I'd put the capacitor in parallel with the terminals of that device. Alternatively you could put it in parallel before the switch on the light.

If you want to get a more dramatic result from less capacitance you could also use a transient clamping device like a crowbar which acts like a zenner diode to divert voltage to a capacitor when it gets above a certain threshold. They make premade devices meant to go on 12V wiring for this very problem that use the crowbar latching method because it requires less capacitance for the same result, it just doesn't help stability for drops, only spikes.

I was saying to put car audio capacitor on light bar power wire .. not car audio system wiring .. I dont think it would do a thing for the car audio system... but it should fade out the power on the hot lead of the light bar so it's no longer a spike in the voltage ... those light bars can operate in a wide voltage range ... if I was having the issue I'd definitely try it ..

 

[Lasherž]

I was saying to put car audio capacitor on light bar power wire .. not car audio system wiring .. I dont think it would do a thing for the car audio system... but it should fade out the power on the hot lead of the light bar so it's no longer a spike in the voltage ... those light bars can operate in a wide voltage range ... if I was having the issue I'd definitely try it ..

If you put a capacitor between the terminals for the light bar it will make the voltage drop worse as the cap charges due to leakage current since the last time it was charged and won't affect the voltage spike because the switch will separate it from the rest of the system along with the light bar. If you put it before the switch it won't, but putting it between the + and ground on the radio will be equally protective. The extra voltage isn't coming from the light, it's coming from the alternator dealing with the light and then not responding immediately when the light electrically disapears from the circuit so the effects of that are felt over the whole electric system of the car except for the now sealed off section including the light bar.

 

[Maverick38344]

He came by today and I looked at it. The pop is after he turns his lights off and the load drops. The voltage spikes back up for an instant then normalizes after the voltage regulator in the Alternator adjusts. The pop is coming from the amp, which is heavily loaded (possibly beyond recommended levels). After disconnecting the amp, the audio pop was not audible from the stereo. My guess is that the amp suffers a voltage drop and the overload on it causes distortion.

 

[Lasherž]

He came by today and I looked at it. The pop is after he turns his lights off and the load drops. The voltage spikes back up for an instant then normalizes after the voltage regulator in the Alternator adjusts. The pop is coming from the amp, which is heavily loaded (possibly beyond recommended levels). After disconnecting the amp, the audio pop was not audible from the stereo. My guess is that the amp suffers a voltage drop and the overload on it causes distortion.

Yeah, sounds about right. Well boys, we may have found one of the few cases where an auto audio capacitor is actually a decent investment. I'd wire it parallel to the terminals on the amplifier.

If you know anyone with a good min/max recording multimeter like a Fluke 187/189 or an oscilloscope it would be useful in determining that peak for the best solution, the crowbar latching devices only work well if the voltage goes beyond what the car normally sees with voltage, so if it peaks from 12.2v to 14.4, well then it's not going to work very well because every time you're driving around with 14.4 it's going to be latched using up power or oscillating from its own voltage drop. If however the peak is at 16v you can be pretty certain that your vehicle's never going to get that high of voltage and it won't latch during normal use except during that spike. If you're not sure and have no equipment to test that peak on you're going to want to go with the capacitor because it will help regardless of the spike characteristics.

When buying an car audio cap it's buyer beware, a lot of the farad ratings are just outright false. I would check youtube videos of people checking their values or just buy maxwells or illinois power caps and assemble the proper capacitance myself. Once again you'd want the characteristics of that peak to know exactly what value you're looking for, but 1-2 farads should be plenty for minimizing the intensity of the pop if it doesn't go away entirely.