boat battery question

I know, like me, a lot of you guys enjoy tieing up for the afternoon and listening to music and enjoying some drinks.

My question is what's a safe length of time to run just my radio without the engine going? Do boat batteries have better life in these situations than my truck? I'd hate to get stuck with a dead battery. I've only owned my boat for about a month and haven't tested it for a great length of time yet. Also, i have just a standard stereo system, no amps or tower speakers yet

It all depends. Best bet is to get a second battery and a switch. This way you alyays have a fresh battery to start on. You can also find out exactly how long it will last and still be safe.

Everyones gonna tell you to get a second battery and a switch...which is the right advice.

make sure it's a deep cycle battery.

Things you want to consider when adding a battery.

-What type of battery do you currently have?(AGM, GEL, Flooded)
-How old is the battery that is currently in the boat? There should be either a sticker or stamp in the case that gives some indication of when the battery was manufactured. It is not a good idea to throw in a brand new battery if the other battery is 3 or more years old. If the battery hasn't been properly maintained then you will shorten the life of you new battery. There is a 95% chance that the battery hasn't been maintained correctly. Maybe your boat is brand new and it is a brand new battery. In that case it should be good.
-How do you want to seperate/combine the batteries? Do you want to use a perko style selector switch.(You have to remember to change it otherwise it is useless. Also you need to know how to use it or you have the chance of burning up alternator. You could wire the batteries in parallel but that mean you only have one battery.(This is bad because you don't have a spare full battery to start off) You could use a seperator/combiner like a surepower 1314 that seperates the batteries when voltage gets below 12.8v and gives charging priority to your starting battery. I like this system because once you install it you don't have to touch anything.

There is probably a million other things to think about but I think these are probably the most important. You probably have a multipurpose group 24 or 27 battery in there currently. These have thicker plates than most automotive starting batteries so are better suited for deep cycling than a starting battery. They still aren't a full deep cycle but work well in most boat applications. When you add a battery you could add the same battery or do a deep cycle as long as both batteries have the same makeup and will be separated when the stereo is playing with the boat off and you really drain the battery. In a lot of boat applications, if you don't mind spending the money, a really good option is to replace your starting battery with an AGM for your starting bank and another AGM for your stereo bank. AGM batteries have good reserve capacity, have thicker plates and because of the way they are made good for cycling. They can also be mounted in on their side so they can fit in weird spots.

Push start it....

with no amps, your battery will run a long time. Just make sure your charge it fully at home before each trip and make sure you have some jumper cables or even better just a jump box to throw in storage. I can run my rhino for hours and hours without charging with a no amp system. You do want to make sure it is a deep cycle.