I'm running a sundown sae1200v1 at 2ohms running voltage is 14.6 it dips down to 13.7-13.4... I'm running 1/0ga about 5 foot run its cca though all I had for ground was a chunk of 2ga it's about a foot long ran to the frame ... also got a 1/0 ga battery ground to the frame even went to a relay harness for the headlights

They will still dim slightly even with your electrical upgraded.  An alt and multiple batteries will reduce it but only way to totally eliminate it is to have HIDs

Pretty much what cloud said. There can be a pretty noticeable dim even with big electrical just due to how little difference it takes to be noticeable, if it's really that bad.

lame there just two basic 10s maybe 700 watts top alt is 150amps but who knows what it's actually at battrry is also a new hd one but ill just go the hid route

thanks for the quick replies was almost tempted to order a bunch of 0ga welding wire ill save my money

Iv had a 220 amp alt. 5 75 amp hour batts and 2 runs of 0 and when running even 1-2k rms I would sometimes have some dimming. Even when volts stay up

i got hids, ddm tuning is good company to buy from

without a battery in the back or a dedicated front to rear ground, you have no decent ground which will cause voltage drop.

You guys are kind of missing a bunch of basic laws here.

 

1.  Any upgrades in getting current to your amplifier (and decreasing voltage drop across that path) is going to lower the voltage level at the main battery up front due to the lower resistance between it and your amplifier.  This will in turn cause increased voltage drop at your headlights as they are fed off of your front battery.

 

2.  To decrease the voltage drop at your front battery (where your headlights are fed) you need to get the amplifier sourcing it's current from somewhere else, like another battery closer to it.  

 

3.  If you lower your ground resistance between the amplifier and the front of the car you again lower total overall resistance and enable the amplifier to draw more current from the front battery and in turn have more voltage drop to your headlights.

 

4.  Honestly, who cares if the headlights dim anyways?

Don't forget to run a sealed battery IF it is in the passenger compartment. Conventional battery's let off toxic gases, as why they are under the hood. I have even seen battery's explode from high wattage system's. Spraying liquid acid EVERYWHERE.