voltage drop issues.

Hello again, Voltage at the amp is dropping down as far as 10.5 volts. My headlights dim as well. I have a high output alternator made by powermax (220AMP max). I have 4 gage wire running to the amp, and 4gage also grounding the amp. The Big 3 was done using this guide with 0-gage wire ( Big 3 Upgrade 00-04 impala). I removed the capacitor I had from the trunk, many people said it was useless. Any ideas on how I can get rid of this drop? -Details- HU: KDC-X794 (Crossovers set, no bassboost, natural sounding EQ set.) AMP: JBL GTO 1201.1 II *~1200W RMS @ 2Ohm* (Gain is set to around 1/3 of a turn.) (Crossover @ 100Hz) Alt: H/O Powermax Alt (220amp @ 1500RPM) Bat: Interstate Megatron II 700 CCA Front Doors: Alpine SPS-600 6-3/4" Rear Deck: Stock 6x9 (open to upgrade ideas) Cable size from bat to amp: 4 Gage Ground: Used dremel tool on trunk body, 4 Gage Subwoofers: Two RE SE-X 12" 4Ohm, wired to 2 Ohm (600W RMS per sub) Box: L port 4.0-Cubes @ 33Hz

You may as well use the cap since you have it, though it's probably best up front to help avoid dimming.... The "useless" cap advice is to prevent people wasting their money since the solution lies in bigger alternators or batteries. But once obtained, a cap may as well be used. (They do have some legitimate uses.) At 1200W => ~ 120A, your alternator should be big enough. You need to determine where the drop is occurring - ie measure from battery- to amp ground, and battery+ to amp +12V, and then each "segment" in between. Tackle the biggest drop first. At 120A, you'll get ~ 0.1V/m drop with 4G. Double up to halve that drop, or 0.06V/m for 2G etc. A second battery next to the amp may help, but where the voltage drop is should be determined first. (2nd battery should have a battery isolator, be an AGM, etc.)

Is it Dipping momentarily to 10.5 volts on the bass notes, or is it dropping to 10.5 volts and staying around there?

Make sure all connections are tight.  Start at the battery posts and work your way back (make sure they are clean!), check that the fuse holder it TIGHTLY holding the fuse.

ac0j wrote: Is it Dipping momentarily to 10.5 volts on the bass notes, or is it dropping to 10.5 volts and staying around there? Make sure all connections are tight.  Start at the battery posts and work your way back (make sure they are clean!), check that the fuse holder it TIGHTLY holding the fuse.

Only on the bass notes. Thanks for the tip Oldspark, looks like I'll be taking voltage measurements up front today after work!

An afterthought - it could be slow response of the alternator, but I'd expect it should react well within a second.... But any excessive voltage drops are nice to know. Or eliminate.

I would start by moving the ground wires and then, well it goes to alternator and add a battery and isolator.Gary Sather