Author Topic: 2nd battery install question  (Read 1929 times)

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Offline RazorJack

2nd battery install question
« on: March 28, 2014, 01:42:38 PM »
So I'm attempting to add a second battery to my 19' SR.  I picked up a Blue Seas switch, one of the basic ones that is 1,  2,  1+2, and OFF.  I have a second battery ready to go, and will be picking up some cable and the rest of what I need in the morning.

I've been reading a bunch of information on how to go about this, and it doesn't seem terribly difficult.  My plan is to install both batteries in the starboard side.  Next winter I plan to undergo a complete rewiring, as well as plan to relocate the batteries up forward, so I'm not wanting to get to fancy with this setup.  I just want the peace of mind of that second battery for this fishing season. 

So, in reading all these tutorials and such I keep getting stuck at the same point..... According to everything I read, the positive cable from the motor goes to the "common" connection on the switch.  As does the positives from accessories etc.   Positive from Battery 1 hooks to "1" on the switch.  Positive from battery 2 hooks to "2" on the switch.   A negative cable then gets ran between the negative post of battery 1 and the negative post of battery 2, jumpering them together.  This is where I get confused.... What do I do with the negative off the motor?  Do I hook it to the negative on one of the batteries?  Do I ground it out elsewhere?

I'm anxious to get this project underway, as its fast approaching ling/halibut season. I'm hoping to tackle it this weekend if I can get over this bit of confusion.

Thanks for any help!

Nick

Offline Threeweight

Re: 2nd battery install question
« Reply #1 on: March 28, 2014, 01:59:21 PM »
Here's a good graphic showing what I'd do...



Add a negative bus bar (a hi-amp one), and run the ground off the batteries to it.  Then you can run individual grounds off of it, rather than piling things on to the battery post (a marine wiring no-no).
Former Sea Chaser 17 owner
Wild Card, Hewescraft Ocean Pro 220, Honda 225 and 9.9

“Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed.”
       --- Hunter S. Thompson

Offline RazorJack

Re: 2nd battery install question
« Reply #2 on: March 28, 2014, 02:20:30 PM »
Thanks for the response, Threeweight.  That's a great little diagram. 

I keep coming across the term "bus bar" in my research.  Looks like I need to do a little digging into that.

Mr.Petersen

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Re: 2nd battery install question
« Reply #3 on: March 28, 2014, 03:05:41 PM »
Razor,

A bus bar is a bar designed to hold multiple connectors but the power is shared throughout the whole bar. This eliminates the spaghetti factory of wires off a single connector and will make better connections. What the bar does is act as a conductor so that you don't need to connect tons of connectors to the same screws, good rule of thumb is maximum of 4 connectors all at 90 degrees. Bus bars have ratings, make sure you buy one with the right power rating to cover everything at full load plus additional power if you decide to add more electronics in.

That wiring diagram is almost exactly what I would like to do with my boat. The only additional thing I would add is an over-current protection to the batteries so you don't fry your electronics if you forget to flip the switch when cranking. Blue sea sells an "add a battery kit" this kit has the part that I'm talking about.

That being said, I'm not an electrician, I did just learn a lot about wiring in a sea-grant class but if your not competent with wiring (like me) make sure to do some research before you start your project. Also, I'm not 100% sure but make sure your batteries are the same type (anyone?).

Thanks,

Joe

Offline RazorJack

Re: 2nd battery install question
« Reply #4 on: March 28, 2014, 03:16:08 PM »
Thanks for the detailed info, Kraken.  I've been doing a ton of reading up on this stuff, but its definitely all new to me.    Part of me is even debating if I want to get into it at this point.  If I plan to do a complete rewire next winter anyhow, perhaps I'd be better off just keeping a spare battery on board for emergencies, and just going that route. I don't want to put too much time/effort into this if its all going to be undone next year anyway.

So a bus bar is basically a distribution system.... So instead of running say 4 individual red lines stacked on a battery, you'd run one bigger wire to a bus bar, then the 4 individual lines off of that, correct?  Though I suppose for the negative side it'd be reversed.  Seems like that would keep it all pretty clean. 

Here is a rather dumb question though.... Where does the negative bus block get grounded?  Or does hooking the it to the batteries take care of that?

Offline AlAdams

Re: 2nd battery install question
« Reply #5 on: March 28, 2014, 03:48:44 PM »
According to the class we took - the advice was to not mix the type of batteries. For example, don't hook up a sealed gel battery with a regular liquid style battery. The other regulation was any battery having more than 800 CCA's needs to be fused. Even though moving batteries to the cuddy can save stern weight you'll need to vent them to the outside - again, according to the instructor.

I believe the ground is the negative post on the battery.
You can't trust water, even a straight stick will turn crooked in it - WC Fields

'88 SR w/Skip Tower  '02 Honda 90,'02 Honda 15
Electrical by R. Wyrguy.

Offline Lingripper

Re: 2nd battery install question
« Reply #6 on: March 28, 2014, 04:15:09 PM »
Razor I have a brand new Blue sea switch I just bought then ordered the add a battery kit with the four polls if you are interested
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Offline Threeweight

Re: 2nd battery install question
« Reply #7 on: March 28, 2014, 04:57:03 PM »
Re: the bus bars... I tend to think about them as distribution bars... they are the things you use to distribute power to different devices/loads.  Here's an example of a heavy-duty bus bar that can handle the amps your motor will draw when cranking:

http://www.bluesea.com/products/2104/PowerBar_600A_BusBar_-_Four_3_8in-16_Studs

I only use bus bars for negative loads.  They can all be run together through one circuit, and there is no danger of a stray wrench or splash of water causing a problem.  For individual positive loads, I use a fuse block, like this:

http://www.bluesea.com/products/5026/ST_Blade_Fuse_Block_-_12_Circuits_with_Negative_Bus_and_Cover

These are great because they allow you to have the correct fuse amperage for individual loads (fish finder, down riggers, bilge pump, etc...).  They also include a negative bus system at the top.  They can't handle a huge amperage draw, but they work really well for wiring (and protecting) individual smaller loads.

Blue Sea makes good stuff (but $$$$).  Chances are you will be able to re-use any switches, bus bars, fuse blocks, etc... you install now when when you get around to doing a full re-wire.

Thanks for the detailed info, Kraken.  I've been doing a ton of reading up on this stuff, but its definitely all new to me.    Part of me is even debating if I want to get into it at this point.  If I plan to do a complete rewire next winter anyhow, perhaps I'd be better off just keeping a spare battery on board for emergencies, and just going that route. I don't want to put too much time/effort into this if its all going to be undone next year anyway.

So a bus bar is basically a distribution system.... So instead of running say 4 individual red lines stacked on a battery, you'd run one bigger wire to a bus bar, then the 4 individual lines off of that, correct?  Though I suppose for the negative side it'd be reversed.  Seems like that would keep it all pretty clean. 

Here is a rather dumb question though.... Where does the negative bus block get grounded?  Or does hooking the it to the batteries take care of that?
Former Sea Chaser 17 owner
Wild Card, Hewescraft Ocean Pro 220, Honda 225 and 9.9

“Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed.”
       --- Hunter S. Thompson

Offline Wyrguy

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Re: 2nd battery install question
« Reply #8 on: March 29, 2014, 08:28:12 PM »
I don't know where to start in response to the previous posts here... other than to say, the graphic supplied by 3wgt is a good one, just not the right one for the battery switch that you've bought... The first thing I'd do is return the switch you have and buy the 2 pole switch from BlueSea, a 5511E. It solves a multitude of problems with a 1, 2, 1+2, off (Old Skool type) and will be able to grow with you and any wiring loads in the future. For any more reading, check out Blue Sea Systems... IMHO, the money you spend on anything (including your boat) is worth the cost and peace of mind of doing it right with proper equipment

Rick


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