ph is the NEC abbreviation for farads... the only difference from a capacitor and a battery is the cap will not create its own power it is just a storage device. the rule of thumb is 1 farad to 500 watts but some amps require more. I upgraded my big 3 with 4ga. wiring and saw improvements on dimming so a 1.5 farad on my 250 watt system should do what it is suppose to. When wired in properly and the correct ga. of wire is used with ample grounding the amp wont know the difference between the cap or a battery. power is power no matter how it gets there. You may have had a bad cap or not enough to keep up with your amp. My system I had in my jeep had mtx12 in bandpass box, 4 6" powerbass 3 ways in the doors and 2 alpine 200 watt amps ( 1 was for sub the other 4x50 ) and ran 4ga. power and 2 ga. ground with all 0ga. on the big 3 and I put in 2 1.5 farad caps in the mix and no dimming at all so I know the caps setup will work just not wanting to add isolators and the other stuff to add in 2nd battery