Hi guys,
I have a jbl 1200.1 running 1 audiobahn and my lights dimm everytime the sub hits hard. Now i know to fix this problem i need a cap.. but wat other option do i have in which i do not have to pay a lot of money. i cant afford to chang emy alt i know that is one way. anything else?

upgrade your ground wires in the engine bay, deep cycle battery, new alternator etc etc.

throw a stinger yellow top back there in line with your amps and ground it. It should stop your lights from dimming. Mine bairly do it and i have 3 of them jbls.

Put a bigger power wire running from the alt to the battery and also a bigger ground on the battery. and so on. Bigger wire everywhere you can think of basically.

If you want to do it cheap, first upgrade the ground wire from the chassis to the battery. Most cars only have 4 awg and you should have at least 4 awg running to that amp. Therefore, anything else electrical in the car has to share the same wire. Upgrading to 0/1 awg is easy. I remember seeing an 0/1 awg neg. bat. wire at crappy tire for around $20. Give 'er a shot.

If not, then upgrade the battery. If still no, then all the other main wires under the hood (Bat. to alt, and alt to -)

I think a cap will do nothing for you. I see a cap as a water cistern. It will provide the necessary drink for a big hit, but after that big hit, it desires to be full so it too is now drinking from the system. Then both the amp and the cap are thirsty and your problem is still not solved. But, I don't want to get into the whol cap debate here. Save the cap as a final attempt.

And then get ready to buy a new alternator as adding a second battery on to a factory charging system is a great way to quickly burn out the alternator.

Upgrade the "big 3" wires under the hood with at least 4g wire. Do a search if you don't know what these wires are.

Get an electrical system test done to make sure the battery and alt are performing fine.

If the factory battery in the vehicle is really small upgrading to a larger one may help, otherwise buy a bigger alternator.

It's probably less work to put a cap in, but won't solve the problem, just patch it up. We spent so much time in my car upgrading EVERY wire. This means block to body, body to battery and alt to batt have to be added to to handle the additional load. I've seen people run 4 g back to the amps and the charging wire and ground wires and like spaghetti. I just shake my head. I think this improves most systems but it can be a pain in the arse.