Is running 2 batteries without any kind of switch ok??

dajuice

I have just finished installing 2-12 in subs and 4 tower speakers in my Tige 22iR. I bought a 1000 cranking amp marine battery and just hooked it straight to my existing battery without any kind of switch. I have a 70 amp alternator so will running the batteries this way mess up anything??

Magic · Outlaw Joined: 27 Jan 2003 Posts: 240 City: Seattle

what will happen:
- higher charged battery will try to charge up the lower charged battery
- you're alt. will be trying to recharge both batteries at the same time (big load on the alt.)
- one of the advantages to 2 batteries is a back up for starting or one to run accessories. you don't have this.

When you do this, I pretty sure that you should two of the same battery and same age. There is a bunch of other problems you will run in to, I'm sure some one else will pipe up on what I have missed.

Might want to check out www.hellroaring.com for more info. Also, you really should look into an isolator.

George · Addict Joined: 12 Jan 2003 Posts: 552 City: Chattanooga

thats how i have mine set up and no problems yet. i think the switch is for when you want to isolate one battery to run your system and then still have the other one still charged to start the boat.

skobi1 · Addict Joined: 15 Jan 2003 Posts: 639 City: eugene, or

It is not going to cause any harm to your boat. But like Magic said the larger or more fully charged battery will try to equalize with the smaller or lessor charged one. This will lead to a shortened life span of both batteries. It is always better to replace batterys at the same time, think of them as shoes-- you don't go buy just one if a toe blows out, you have to get another pair. By hooking them in parralel you have basically just created one large battery, and have not gained the advantage of a dual battery system.

riverside · Posted: Apr 29, 2003 10:59 pm Post subject:

i run all my extra,s thru the 2th batt like stereo-lights -heater ballast pumps etc. no switches just a 55 amp fuse between the 2 batterys.
3 years problem free

Tim Krasin · Outlaw Joined: 13 Feb 2003 Posts: 104 City: Houston, TX

Really consider using a continuous duty solonoid (similar to a starter solonoid) and it'll only activate when the boat is running, otherwise the stereo/accessories battery will be isolated. This will keep a good starting battery from doing anything except starting the boat. I saw another guy on this site with this type of setup (Red Air Nautique with killer system) - though it is a great way to set things up. Also - really consider running the same type/age/brand battery for anything where two batteries will ever be running in parallel.

skobi1 · Addict Joined: 15 Jan 2003 Posts: 639 City: eugene, or

Riverside, I'm confused as to why you would fuse the parralel link between two batteries. When battreies are wired in parralel, like I mentioned above they act just like one large battery. The next time you have a voltmeter handy test your batteries, both will always be the same voltage when wired in true paralell with no switches