something that stops my system before it drains my battery?
 

is there anything like this? I heard about something like that and am just looking to find out some general info. about them. thanks

Yes and no, if your running a 2nd battery they sell a relay kit, will kill the stereo systems battery but leave the main alone.

programable relay???? of some kind....you would need a programmer to make you a device to switch the relay i guess, its a really good idea though.

Not programeable, just a relay kit kinda like this:
http://www.oznium.com/relay200

sure you could design something using adjustable voltage regulators, if the input voltage drops below the regulators set voltage causing a relay to go to a normally open state... where it would control either the ignition wire of the deck or the remote line to the amplifier.... if u set voltage to say 11 volts it would be safe... but you would also need some type of latch to keep it from returning to the on state because most batteries will recuperate (sp)after a few seconds or minutes after the load is disconnected... and you would need a reset pulse ... maybe when you start the car ... most cars drop accessory during crank... when ignition and accessory are present it would re-engage the system
just an idea


sorry if it sounds confusing

Good question. If you don't want to spend money, leave the car off and see how long it takes the battery to drain. Boost it and note how long it takes to regain a full charge when driving. I don't know how to measure that though. You'll atleast have a timeline. Or don't leave the stereo on for an hour in the driveway, go for a boot.

Googled

"... unless it's a deep cycle battery, if you run it to below about 10 volts, you've damaged the battery and it'll need to be replaced anyway".

"The car has to be above about 900-1200 RPM so voltage goes up to 13.8 to 14.4 volts to create a forward bias across the battery and put it into a charging state".

this is what you want:

Battery Buddy.Com

i wanna make somthin cool one day....like weedwacker motor turning an alt, so it will power your system...to bad there terribly efficent though

You want to use a seperate tank of gas to power an audio system and have to listen to it? A weedwacker motor would be very INefficient.

okay well thanks for the replies, I guess i'll have to look into either adding a second battery or finding something like the suggestions