Battery Size

[out n about]

hi all,

i was wondering if u could give me some advice on batteries for my boat. i wanna put a bigger battery than the one i have now so i can run more electrical items like sterio and 2-way so on, i think i have just a small standard car battery, if i do put a bigger one in will i need to do anything to the alternater as that is what rechargers the battery isn't it?

cheers,

Dave

[Guest Sea Tow Botany]

G'day Dave

Like swordfisherman said you will need to get a marine battery,and running 2 banks of battery is the way to go if you have room

In your case i dont believe you will need to worry about your charging system im guessing your running a small outboard with a 450cca battery, but of course you should check with your dealer

On my boat i run 2 radios, deepth sounder and gps off a exide stowaway 620cca battery, these batterys also have limited deep cycle capabilitys which makes them my number one choice

ps. Just so you know if you do go the 2 battery way you would want to parrallel the battery not series connected. 2 12volt batterys connected in series will give you 24 volts

Dave

Sea Tow Botany Bay

[Grantm]

Agree with the above comments. Dont think you neccessarily need two batteries though. One good size 500cca plus marine battery will do the trick. FORGET deep cycle batteries for a starting battery. They hate being charged by an alternator and are not designed for it. Your alt probably punches out around 35amps which will reduce the life of a deep cycle. Good quality marine battery will be fine.

[BROWNIE]

Sorry about raising an old post. Was wondering how much an anchor light and cabin light would drain a battery if left on overnight. Would I have trouble starting?

[Grantm]

gday Brownie,

How longs a piece of string ? Tough question to answer id say cause it totally depends on your battery type, condition, size etc. It can also depend on current draw of the light any other accessories and 'leakage' and how much cranking amps is required to start your motor.

The same question can be asked if an interior light left on in your car will drain you battery overnight. The answer : some will - some wont.

Best bet is to ensure you have the largest best quality battery you can find. In my opinion an anchor light shouldnt drain a good quality marine battery overnight, if it does upgrade it.

If your not sure test it at home overnight and see how it goes.

Hope this helps

Edited March 29, 2006 by Grantm

[Ramjoh]

Hi Dave,the battery you are after is the marine heavy duty one ,not to be confused with the deep cycle battery that many of us run our electric motors off .The heavy duty marine battery has a lot more cold cranking amps to start motors and the like and will charge easily on your alternator .You may want to get two of them and run them in series with a switch to change from 1 to 2 or both batteries which gives you a big hit when cold starting

Cheers Swordfisherman

If you run 2 x 12volt batteries in series you will pop all your electricals with the 24volts. I would suggest parallel connection.

[out n about]

thanks for all the advice guys, i have a 4.2 runabout with a 35hp on the back i forgot to mention it before. i might shop around in buying the 2 marine batteries. the only problem ill have is how to hook both batteries up to the engine so that they could charge...

Dave

[pekingduck]

Dave, I've just recently set up dual batteries on my boat, so if you need help on how to wire it up let me know.

You will need to buy a switch and all the cables and connectors.

getting everything together takes a while, but hooking it all up is pretty simple.

[out n about]

that would be great pekingduck, would appreciate the help, just got to find the time and money to get everything together and go buy the things needed

[pekingduck]

ok:

you will need to buy

Battery switch (approx $44)

If you want it done properly so that both batteries remain fully charged you will need to get a Voltage Sensitive Relay This will mean that once battery one fully charges it will switch over to battery 2 to fully charge.

Cables: Get Battery and starter rated cable ($7 per M)

Battery Lugs: you will need 10

Wiring up:

from the outboard --positive cable to the common connection of the switch (both)

Negative connects to negative of battery 1

Battery 1 -- Positive from battery 1 connects to B1 of the switch

battery 2 -- Positive from battery 2 connects to B2 of the switch

Battery one and battery 2 connected by negative terminals.

optional: Buss Bar connection from common switch to negative of battery 2 where all my electronics are hooked onto.

Draw a diagram if it makes it easier for you.

I was told never to leave the switch at both as it drains whichever battery has less charge.

I usually alternate between batteries on fishing trips whereas some others will use B1 for the trip out and switch to B2 for the run back.

hope this helps.