Amp and Second Battery question

[79Hawaiian]

Just bought a pair of Polk Momos and shopping for an amp. I am looking at the Punch 401S (http://www.sounddomain.com/sku/ROC401S) . Any feedback would be great. My major concern is power. I want to add a second battery but not sure if I should go with a standard auto battery, optima, or a sound system battery. I have seen the Stinger SP800 Dry Cell Battery (http://www.sounddomain.com/sku/STISPV44) advertised for auto systems, not much cranking power but long discharge rates (good for kicking it without starting the engine every half hour). Anyone use these? Am I being paranoid? I only want to run 200 watts. Is a regular auto battery enough?
Also these amps show an imput voltage of 14.4v. That is the output of the alternator, not the battery. Does this mean amp power drops when you turn the key off????
:confused:

[FastRat1]

just my 2 cents...no matter what battery u decide on..i would run a battery isolater switch..which allows u to use either battery or both and to charge either one or both when the motor is running..i run 875 CCA auto batteries with n/p..i also have a Kenwood 200 watt amp..i use one for the music and one to just start..then when i'm running..i just charge the one i used for the music..just a suggestion
Ron

[Havasu Hangin']

79Hawaiian:
I only want to run 200 watts. Is a regular auto battery enough?With only 200 watts...I wouldn't worry about any high-end batteries. I would consider a Marine deep-cycle (instead of an automotive), as there's probably a good chance you'll run it down to the bottom. They don't cost alot more.
79Hawaiian:
Also these amps show an imput voltage of 14.4v. That is the output of the alternator, not the battery. Does this mean amp power drops when you turn the key off????Yeah...it's a way of showing potential customers higher output on an amp.
Since watts = volts x amps, anytime you change volts, you affect the output of the amp. Most people don't notice, as the volume knob has more of an effect.
For example, if that amp is actually producing 200 watts at 14.4 volts (alternator charging voltage), then it will probably put out around 150 watts at 12 volts (battery voltage).
But who would pay that much for a 300 watt amp?

[1FastHallett]

i would use a deep cycle battery for the amp and have at leat one automotive battery to start the boat. deep cycle batteries do not like to be recharged untill they are are almost or completly dead, it shortens their life span. its actualy good for them (deep cycle) to let them completly die and then recharge unlike automotive batteries. if you need any help with electronics advise i teach auto electronics and drivability so i can help. im geting ready to install a system in my boat as well and plan on running at least one maybe two deep cycle batteries just for the system, but i also plan on having over 1000 watts so i need the power!