BUMP!Anyone? I have 2 batteries, a stock up front and a optima yellow top in the back, that should be fine for the 1200 watts + a 4x90
what else could it be?
I would say that a Yellow
should be enough to power about 1400W RMS, but you are pushing just a little more than that. The thing is, if you have a weak alt and the batteries are not keeping charged because of that, then you are eventually going to run them down to the point where they no longer help very much.
1) First things first, go buy the DMM. You have no right installing your own audio if you don't have a $5 DMM in your tool box. It is that essential.
2) Now check the resting voltages of both of your batteries. You do this by removing the NEG- wire from the battery you are checking first, then check the voltage with the DMM. Check each one individually. If the front battery (assuming it is stock) is below 12.6v or if the Yellow is below 12.8, then you have batteries that are not fully charged. Make sure you put the NEG- wires back on after testing.
3) If they are fully charged, now start the engine and check the voltages again, but this time, leave the NEG- wire attached. Note the voltages at each battery. If either of the batteries is greatly different at this point, you have a wire disconnected somewhere. You should expect to see about 13.6v to 14.4v in this test and both batteries should show a very similar number.
4) Now that you know that your batteries are getting voltage from the alt and are keeping charged, you can now test your voltage of you batteries under load. Turn you audio on to a moderate volume. I usually use about half volume to start. Now again check the voltages as you did in step 3. You may see the voltages drop during a bass note. That is to be expected to some degree. If you are seeing a drop below 12v, that is where you would expect to see some light dimming. If you are dropping below 11v, that is where you would expect possible protect modes kicking in. If you get down to 10v, you can be assured that your amps will cut off in order to protect themselves from overheating due to low voltage.
5) If you have completed all of these steps and still have issues, I would still check all of your wiring going to and from the HU and see if you have a bad ground or a short somewhere.
Make sure you post back so we know what helped.