I have a 500 RMS AMP with a 600 watt RMS speaker and I have a 6 or 8 gauge wire running to the AMP. I have a 1 farad cap installed and I have 2 small 12v 20 amp hour* batteries. I know what I am doing but I am wondering if it would be better to have a switch installed to turn the batteries on and off or If I should just hook them up so they turn on with the radio.
*Amp hour means if it is 20 amp hour it can draw one amp for 20 hours or 20 amps for one hour.
The batteries are gel cell batteries instead of liquid and they are about 1/4 the size of a normal car battery so I don't think they will draw too much from the alternator. I want to install them because I don't want my battery going dead when I am in parking lots
Lets do the math here, first of all the 500 watt amplifier requires a nominal 40 amps to drive it so you need a minimum of 6 and preferably 4 gauge wire to avoid voltage drop.
Secondly the 20 amp hour gel cells will deliver only about 10 amp hours at the one hour rate before they drop below 12 volts. So at 40 amps output they will last about 20 minutes max.
Your best option if you actually want to run the amp when the engine is not running will be to install a 600 to 800 amp hour deep cycle battery in the trunk and use a 100 amp knife switch or 100 amp relay to isolate the amp battery from the starting battery when operating the amp when the engine is not running.
Lets do the math here, first of all the 500 watt amplifier requires a nominal 40 amps to drive it so you need a minimum of 6 and preferably 4 gauge wire to avoid voltage drop.
Secondly the 20 amp hour gel cells will deliver only about 10 amp hours at the one hour rate before they drop below 12 volts. So at 40 amps output they will last about 20 minutes max.
Your best option if you actually want to run the amp when the engine is not running will be to install a 600 to 800 amp hour deep cycle battery in the trunk and use a 100 amp knife switch or 100 amp relay to isolate the amp battery from the starting battery when operating the amp when the engine is not running.
Lets do the math here, first of all the 500 watt amplifier requires a nominal 40 amps to drive it so you need a minimum of 6 and preferably 4 gauge wire to avoid voltage drop.
Secondly the 20 amp hour gel cells will deliver only about 10 amp hours at the one hour rate before they drop below 12 volts. So at 40 amps output they will last about 20 minutes max.
Your best option if you actually want to run the amp when the engine is not running will be to install a 600 to 800 amp hour deep cycle battery in the trunk and use a 100 amp knife switch or 100 amp relay to isolate the amp battery from the starting battery when operating the amp when the engine is not running.
