Alternator or Battery Problem?

It has a new 24F AGM battery bought back in October/November, along with the FORD DIODE, was constantly 14.2-14.7 with my accessories on including the ultimate headlight upgrade along with my 1200w RMS stereo.

The last few months I’ve noticed that the amp for the sub cuts out as if not enough juice. Doesn’t go into protection mode, turn it down or I restart it and seems ok again. I’ve checked wiring and everything is ok.

In the past few weeks, it has gotten worse and my voltage only only hovers around 13.1-13.5 with my radio playing pretty loud lol! I’ve thought maybe because of the bad heat wave we’re going through. Been running this set up for about 4 years, assuming this is the original 7 OEM alternator.

Battery as it sits, fully charged.


Running with no load


Load test, lights on, A/C on, fogs, light bar. Radio playing at moderate volume, driving around town it will hover 12.9-13.5 depending how loud I play my music.


And off it was 12.8 volts.

What do you guys think??? I’m thinking alternator.

 

Could be. Just had my alternator in my 2013 start to go, one of the diodes went bad.

 

Looks nominal. Voltage does not imply amps...but with an 8 mo old bat you should be fine. Go back and check/clean/tighten the various connectors to your stuff.

 

You could check the actual alternator output voltage.
Check it from the alternator terminal, and not through the battery.
That should help narrow down the “voltage” question.

 

checked the amp, checked the power wire in the engine bay. Behind the headunit as well.

 

If your battery is starting your truck then you know it is capable of dumping hundreds of amps. Not a battery problem. Connectors, wires or components is where your issue is. By "checked the connections" I'm assuming you disconnected, cleaned and reconnected them?? How much current does your amp draw and what gage wire are you using?

 

Yes. There’s 4x 30 amp fuses and I’m using 0 gauge wiring, a true 0 gauge.

 

I'm surprised you're getting any reading with the black lead not plugged into the common port.

 

Hawkeye...

 

help me out lol!

 

Agree on testing the alternator at the output, but that does seem a bit low. Do a health check on the battery; new doesn't always mean good.

 

Do you have any stiffening capacitors connected for the amplifier?

It will help with power hogs such as your amplifier.

If you do maybe one of them is having a connection issue or is going bad.

 

I don’t have one, which one would you recommend?

 

You have the meter set correctly. The test lead should not be plugged into the far left terminal.
That and COM allow you to measure up to 10 amps through the meter. The COM terminal is common to the other 2. The jack on the right is for everything else.

 

Respectfully disagree; the meter is set to the 20V DC range. Therefore, the negative (black) lead should be connected to the 'COM' (Common) jack and the positive (red) lead should be connected to the V/O/ma jack. I'm actually not sure what a meter would do if you have it connected to a voltage source in this configuration; I would have thought it would blow the voltage fuse, but apparently not.....

 

The meter is set correctly to the proper range 20vdc is what I meant. But ya, I can see the confusion. I had to zoom in and make sure it was DC and not AC when I wrote that.

I like the little transistor tester it has. Sadly that's pretty much a relic now with surface mount components.

 

So put the black lead in the middle???

 

Would you say the problem is the alternator??

 

Very difficult to say, but based on what you've said, I would start my trouble-shooting there.