Car voltage problem

[SlayerAk23]

I am having a problem where my radio would turn itself off. It is an aftermarket setup. Watching the voltage meter on the capacitor that I installed when I initially did the radio, shows the voltage running low, about 11.5 volts. But it always doesn't run that low, the voltage sometimes would also run at about 14.3 volts and I would have no problem with the radio turning itself off no matter the volume. Could the alternator be going bad because of the low voltage when the car is running? And this also started to happen after the winter, which we had some really cold days in the Chicago area. If anyone could help me out, I would greatly appreciate it.

 

[ChrisJ]

I am having a problem where my radio would turn itself off. It is an aftermarket setup. Watching the voltage meter on the capacitor that I installed when I initially did the radio, shows the voltage running low, about 11.5 volts. But it always doesn't run that low, the voltage sometimes would also run at about 14.3 volts and I would have no problem with the radio turning itself off no matter the volume. Could the alternator be going bad because of the low voltage when the car is running? And this also started to happen after the winter, which we had some really cold days in the Chicago area. If anyone could help me out, I would greatly appreciate it.

I'm sure others will have different opinions but my first step would be to confirm the voltage with a reliable instrument such as a quality DMM. I would never trust the built in volt meter on a capacitor sold for automotive audio.

Even though, it may be true and even make sense, I would not trust it and would want an accurate measurement. You're going to need a decent DMM to troubleshoot the problem anyway so I would recommend buying one. Personally, I'm biased towards Fluke meters but I use my meter constantly so you might not be able to justify the cost of one.

If I was you, my first step would be to check the voltage across the battery terminals using a known good DMM. If you see 12-12.5V with the car off and your radio is messing up you have other issues somewhere else. You can start the car and check across the battery again to see what the alternator is doing, but the radio should work fine without any help from the alternator assuming the battery is decent.

 

[ChrisJ]

This looks like an ok meter for $20.
Be warned it will be slow and jumpy compared to a good one, but it should get you by.

Amazon.com: INNOVA 3320 Auto-Ranging Digital Multimeter: Automotive

 

[sonic007]

100% agree with ChrisJ on this one. Never use that as a baseline reading. The voltage will read different at the radio.

Is the radio shutting off with the car on or just sitting? I know the Sonic can handle it. I have 2 12s and, 2 channel, 4 channel, all speakers and aftermarket radio. I blast it all the time with no issues.

 

[SlayerAk23]

Thanks for the replies guys. I borrowed a meter from my school and did some poking around. Ended up being that the capacitor went bad. After I disconnected the capacitor and had it by itself, the voltage on it dropped to about a volt pretty quickly. Connected everything back up without the capacitor and it's all good. Thankfully it wasn't a bad alternator.

 

[SlayerAk23]

Oh, it was never the actual radio. It was either my processor or amp.

 

[ChrisJ]

Good to hear. Back when I had an A/D/S/ + Eclipse system I didn't run a cap as I was afraid of them. I had the system in the standard cab of a pickup so it was going to end up close to me.


I'd still advise buying a DMM as I couldn't imagine living without one. Personally, I also have a Simpson analog meter that I use for certain things, but I doubt you would need it. The analog meter is nice if you're trying to observe change rather than exact measurements. I'll use the analog meter when I don't feel like carting a scope around.