Two batteries?

I just installed one pair of tower speakers on the tower. And I just got to thinking when I want to add another set and what not, is it possible, or even needed to add a second battery to the boat. I have heard cars have started to be produced with two batteries: one to power the engine and one to power the electronics. Just a thought...

In my opinion a second battery is an absolute must. Otherwise, you are rolling the dice every time you are underway. Plus, with a second battery, you can listen to the stereo when shut down and not be constantly thinking about whether you are about to strand yourself.

Make the investment.

A second battery will only be a benifit IF you either install the extra hardware to automatically isolate the batteries or have the discipline to do it manually.

You can add all the battery capacity you want, but the bottom line comes down to how much you get out of the alterator. If you use more than you produce, your batteries will go dead. If you have two or twenty batteries, and they are all connected together, they will all go dead together.

What will save you is if you have a battery that is used only for starting the engine. This battery will need to be recharged, so you will need to switch the battery switch to ALL when the engine is running and then remember to switch it back when you stop. If you start and stop a lot (like a wakeboard boat should be doing) this will be an incredible hassle and you probably won't do it.

You can also get a "battery isolator" that will keep the two batteries separate and yet still charge them both. Unfortunately, the isolator introduces a voltage drop in the charging circuit that results in a dramatic loss in charge rate, so if you were having a problem with the alternator not keeping up before it will only get worse. You may not be able to run the stereo as much, but you will always be able to get started again.

A third choice is what is referred to as a "battery combiner". This is essentially an automatic battery switch that connects the two batteries together whenever there is a source of charging. This gives you the best of both worlds, as it provides automatic isolation and it has no insertion loss.

I agree a second batt. is a no brainer. Going with a manual switch is cheap and easy to intall. You do have to remember to switch the batt. over to avoid running down both, but, as long as you are at least a half wit it is no problem.

There are isolators on the market that dont create excessive voltage drop that work great.

Buy the biggest second batt. you can fit.

I use an automatic relay (avl. at "tweeters")for about $75.00. It hooks up in line so when the key is on and the boat is running both batteries charge and when the key is off the amp & stereo just draw from the second batt. This has been a total no brainer, I have used this in two boats for about a year now and have had nothing but great results. if you need a more product 411 let me know.

A 2bd battery is always good. When on the water I try to always carry a jumper battery pack. The jumper battery pack has proven to be worth its weight time and time again. Not to get my boat going but to get other people running. (Easier and safer than connecting cables to your truck or boat)

I'm a jumper pack and two batteries guy. I have the two batteries hooked up through a Hellroaring Isolator, which is a solid state relay device. If you just hook batteries in parallel, they will discharge between eachother. If you use an isolator, you can prevent this. Cheap isolators use diodes, they drop voltage and can damage batteries due to undercharge. Relay isolators work fine, but they are mechanical and will spark. The Hellroaring is biased so that only the charge side can turn the relay on, so the charge can only happen in one direction, like a diode, but with the low on resistance of a relay. As the other guys have said, it is the best of all worlds, but simpler, cheaper solutions (1/2/all switch) and relays will give the same results, with a little more hassle. See my page for pics of my install, www.epicmarine.com/how_to.htm It works great so far and I don't have to think about it.

dual batteries need an isolator, which can be purchased at any Auto Parts store or an RV parts store. It hooks up into your charging circuit and allows you to run a separate circuit for your stereo system which does not touch your primary circuit for the boat itself. You can run your stereo until it dies, and still start the boat no problem. I recommend to upgrade your alternator to 80-120 amps to handle charging dual batteries. The hot ticket is a 3 battery system, one for the boat, and two batteries wired parellel for your your stereo. Your stereo will play for hours!

get a switching silanoid, its the best way to go,and its not that expensive.