Second Battery Costs?

[BoatnFool]

Can anyone give me an idea on what the costs are associated with adding a second battery? I'm thinking it's time to add a switch and second battery so I can use the radio on the boat when hanging out. I've seen diagrams, how hard is this?

[SHIP4BRAINS]

Tell the wife a bigger boat would cost less.

[BoatnFool]

Tell the wife a bigger boat would cost less.

We were on the water Saturday...boys were jumping off the back of the boat and are trained to go off the side away from the lower unit. I tell Lisa, "if we're keeping the boat for a bit, we need to add a swim platform". She says, "lets buy a bigger one with a platform already on it". However, she just used our funds on the new deck. Saving for next year now!!!!

[emilsr]

If you're planning on selling the boat in the near future, just invest in a jump box. To add a second batt with either a perko switch or an isolator (preferred) you're probably looking at $400 to do it right.

[Griff]

You are probably looking at about $250-$350 to do it yourself.
Battery $125-150
Battery Box $50-75
Battery cables $50-75
Battery switch $40-50

The other option is wire a new battery to the existing one with a battery isolator. Then you would have to hard wire the stereo power to the new battery.

[BoatnFool]

Thanks! Leaning towards a jump box as we hope to upgrade in a year or so!!

[SHIP4BRAINS]

What is the disadvantage of simply wiring the two in parallel, besides being able to isolate one for starting only?

[emilsr]

What is the disadvantage of simply wiring the two in parallel, besides being able to isolate one for starting only?

I asked that when our stereo guru hooked up a 3d battery in this manner in our boat. He said basically no disadvantages so long as you kept them up (charged and full of water) and replace them as a pair. We leave our switch to "both" all the time as he recommended so all three are running (in effect) in parallel.

I honestly have no idea how it all works but I do know how to follow directions.

In BnF's case I suspect he's looking for a way to run a battery down with the stereo and still get home.

[BoatnFool]

In BnF's case I suspect he's looking for a way to run a battery down with the stereo and still get home.

Exactly!! Only have 1 amp so I'm not pulling much juice, but don't want to get stranded. I tend to forget about starting the boat and recharging if i'm in the water relaxing and enjoying a beverage.

[bsloop]

What is the disadvantage of simply wiring the two in parallel, besides being able to isolate one for starting only?

When you run down a large bank of batteries, it creates signifigant resistance for the alternator and you will burn it up. Taking that huge reserve from 12v to 14.4v puts a load greater than the 55-100amps your alt is rated for and it burns up.

I have run with two isolated 31 Optima blues and a 31 start for three years with no problem.
My isolator gave up so I figured I would just wire them together since I have my generator/power supply so I never have to worry about no being able to get started. Sitting in the cove and playing stereo for couple hours w/ no gen running, batteries down to 12.1ish, no problem starting given the huge reserve of three batteries, when I get back to the dock 15 min later, electric smell, whining noise, alt incredibly HOT, and alt not putting out what it is supposed to. I was in Havasu early spring, so I was able to find an electric shop and got a second 90amp alt (former was 110amp). Burned it up 4 weeks later.
My buddy didnt heed my warning of experience and just did the same to his.

As you increase alternator size, car guys talk about the BIG 3, its a BIG 2 for a boat but still wise to upgrade the power wire from alt to starter from the 10ga to 4 or 1/0 ga to handle the bigger output.

OP, Griff has the $$. You have to pay to play.
Make sure you are fully charging all batteries when you return to the dock.
Ususally the alt will not have time to completely recharge.

[Soul Asset]

Make sure you are fully charging all batteries when you return to the dock.
Ususally the alt will not have time to completely recharge.

x1 I carry an extension cord with me to charge the batteries at the dock.

Right now, I run a Perko switch, but will change over to an isolator at the end of the season. I prefer to have everything "automatic" so I don't have to remember to switch things over. I'll run the stereo and what not off one battery and let the other handle starting the engine.

[Nightlife1970]

I suppose if you run large gell cell type batteries it MAY cause a problem with your alternator. I have never had a problem running 2 normal deep cycle's off of an alternator. I have 2 batteries per motor now, and have been that way for 4 years. Have had the same setup on all three of my boats over the last 14 years, and have never burned up an alternator.

[JMS]

I can sell you four batteries already set up in billet boxes, with switches.....The deal is though it comes with a boat. Your wife has been on my boat so getting the ok should be no problem...

[ggspot]

What is the disadvantage of simply wiring the two in parallel, besides being able to isolate one for starting only?

i just added one parallel in spring 09 never really had any trouble till few weeks back run both batts all way down and killed a cell o well maybe we should of put the charger on if we were going to sit at the dock full blast with 3 amps runnimg 4 3hrs now we have 2 more new batts and a new jump pack