added elect. water pump also have a sterio system with a amp. i have a optima battery its the second one. 1st one lasted two years. i dont think alt. is big enough now does'nt seam to charge battery completly. is a 140 amp alternater big enough? 96 z28

 

Both your pump and your amp should have a Watts rating. SInce Volts X Amps = Watts. So if we assume worse case your car needs 60 amps for normal use. That leaves 80 amps or 960 Wats of power left.

Battiers some times just fail. If they didn't they would not have all that pro rating on them. A 6 year battery would get you a new battery after 2 years. The 6 years is more of a average. Letting them sit over winter without a tender would be a lot harder on them then have the car run off the battery at times.

 

what volts are you showing when motor is running and when motor is off?