alpine 2000

So i recently got the 4.0 HDC on my MRP M2000 at 2 ohms and my car is dimming pretty bad, my alt. is a stock 85 amp. its also a crappy NAPA battery under the hood. I know a new alt would be ideal but don't have the money right now. would i be able to just get a yellow top and run it... Big 3...