Is 2nd battery a must when running 2+ amplifiers

[cab13367]

Another newbie question - what is the reasoning behind having a second battery when having a stereo system with multiple amps? Is it because the amps will run the battery down when listening to the stereo with the engine not running, and thus, the 2nd battery is insurance that you can get the boat started? If this is the case, is a battery minder an acceptable alternate (shuts the power off when the battery gets below a certain voltage, allowing enough juice to start the engine) along with a portable battery pack?

Or is it because the amps draw so much juice that one battery is not enough to supply the juice needed by the amps and the engine and accessories?

I don't have a problem adding a second battery other than the space it takes up so I want to make sure I understand it's purpose.

Thanks in advance to the stereo experts out there.

Al

[zabooda]

I only have one battery and I have a stereo and a seperate amp for the subwoofer. Nothing really big. I carry jumper cables and I rely on administrative controls over engineered controls. I take the boat out at least every 1.5 hours of stereo operation and charge the batteries while pulling someone. You need to get a feel for what works for you. I'm a skier also so added weight is not good.

[qb12]

I only have one battery and I have a stereo and a seperate amp for the subwoofer. Nothing really big. I carry jumper cables and I rely on administrative controls over engineered controls. I take the boat out at least every 1.5 hours of stereo operation and charge the batteries while pulling someone. You need to get a feel for what works for you. I'm a skier also so added weight is not good.

in my old supra i had two amps, 14 inch sub and 4 tower speakers and used only 1 battery. as with booda, i carried along a jumper box and never drained my battery.

[tlatoani]

I think a jumper box is a good solution, but I'm a bit anal so I just added a second battery. I was also afraid that I would forget the jumper box the one time I needed it. It is pretty cheap to add a battery. (I got an optima bluetop for 155 at Sams, plus ~50 for a relay, and maybe 20 for cables and stuff).

On a side note-I saw a neat jump box with a usb power socket. Pretty cool.

[byronkoz]

A second battery is not only just in case one goes dead, its also to give you more power to your stereo. Its a good idea when running multiple amps and espesially when running a sub, to have more than one battery. Running multiple batteries parralell you'll have a better chance of maintaining a voltage over 11.5 for a much longer period of time, anything under that you take the risk of damaging your amp(s) or if there decent amps then thell probley go into protection mode and shut off. Its really best to have an acc battery and starting battery with a switch/isolator or better yet 2 acc batteries and a starting battery depending on the size of your system.

[bamaspiveys]

so to tag a question on to this I see the perko battery switches, and think I understand howe they work but several people have mentioned a "relay" what is the realy for and where do you get one?

[tlatoani]

so to tag a question on to this I see the perko battery switches, and think I understand howe they work but several people have mentioned a "relay" what is the realy for and where do you get one?

http://www.tmcowners.com/teamtalk/sh...t=dual+battery

Some great info in there. I ended up just buying a stinger relay from ebay-same thing as the one mentioned in the link. Install was easy-the purple wire on my ignition was the switched one just like the mc's.

[byronkoz]

Im pretty sure skiers choice puts a relay+perko style switch in alot of there boats?? This would be the best way to run multiple batteries. Heres a thread I just found on WW that has some good info.

http://www.wakeworld.com/MB/Discus/m...tml?1207863641

[zabooda]

bama,
A motorhome isolation relay would work and is about $15. You need to have it in a ventilated area as when the contacts close they do spark even though the relay is enclosed it could spell trouble around gas fumes. You could goop it up real well and fix that. The attached website has a good explanation.

http://www.neon-john.com/RV/Electric...ion_relays.htm

[tlatoani]

I avoided a switch just because I have kids. If they flip it off while the boat is running it can do some damage. Not likely but you never know...