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Author Topic:   Battery Set-up with Twin Engines
Dan posted 12-28-2008 09:33 AM ET (US)   Profile for Dan   Send Email to Dan  
I used to have a Outrage 17 with a dual battery set-up and big OFF-1-BOTH-2 switch. Now I have a 1990 Outrage 18, standard console, with twin 70hp Yamahas. I plan on rewiring. The batteries are in the console. What size of battery wire will provide the smallest voltage drop? Should I have three batteries? What do I need to charge the batteries while they're in the boat with an extension cord. What switches and other items do you suggest? I plan on cutting holes in the console floor for battery boxes to take the weight off floor and also give me more space in console.

Electronics: Vhf Radio, GPS, Stereo, Amp, Bilge Pump, 12V Outlet.

A list of specific items and manufacturer would be greatly appreciated. Thank you.

jimh posted 12-28-2008 11:29 AM ET (US)     Profile for jimh  Send Email to jimh     
Voltage drop in a conductor is proportional to the current flow and the resistance of the conductor. The lower the resistance the lower the voltage drop, and the lower the current the lower the voltage drop.

The outboard motor typically comes with cables with a conductor size that is appropriate for the current the motor will draw during starting and the length of those cables. When you want to stretch the cables to reach the console, you have two choices:

--you can make the extension cable so large that its resistance is very low, and in this way the total resistance in the starting circuit will be sufficiently low, or,

--you can replace the cables with new cables of a larger size that will be appropriate for the new length.

If you splice in an extension, you typically have to use really large cable to get the total resistance low enough, and you also have the problem of the splice, its connection, where to make it, how to protect it against weather, and so on. If you use all new cables you get a one-piece cable run, and the new cable won't have to be so large.

Dan posted 12-28-2008 08:26 PM ET (US)     Profile for Dan  Send Email to Dan     
Jimh, I was hoping for some specific set up ideas.

Here are some photos of my progress:

I've removed almost all the metal items from gunnels in preparation for sanding.

I've removed almost all wood for refinishing.

I removed all canvas for storage and some minor repairs.

I removed previous owners reg numbers and stickers.

Removed transducers for depth finder and fish finder. I'm planning on selling these items and Garmin 182C on eBay and getting a GPS sounder to replace previous.

I will be replacing all fuel lines, control cables, battery cables and more.

I think this will be the perfect time to lift deck, inspect, clean, etc.

Tomorrow I will try to sand gunnels, and teak piece on top of console, and apply first coat of teak oil. It's supposed to be warm -- we'll see.

jimh posted 12-28-2008 10:00 PM ET (US)     Profile for jimh  Send Email to jimh     
My specific recommendation would be to replace the existing engine battery cables with new one-piece cables of the appropriate size and type to provide for a sufficiently low voltage drop. You can calculate the wire size using resources at ANCOR's website.

I don't see a need for three batteries.

To charge the batteries while in the boat, install a fixed-mount AC powered battery charger. I like the ProMarine chargers. Bass Pro Shop usually has these in stock at a good price. If you don't need extremely rapid charging, a 4-ampere charge rate should be sufficient to maintain or top off the batteries.

Bulldog posted 12-29-2008 01:26 AM ET (US)     Profile for Bulldog  Send Email to Bulldog     
Dan, check out the reference section, dual battery, then check out the "new dual" setup, nice setup allowing the house panel to be fed from either battery and also gives the option to tie two batteries together for emergency starting. I would normally keep the systems seperate to not cause any problems with the two voltage regulators. Two batteries are plenty.......Jack
Dan posted 12-29-2008 10:52 AM ET (US)     Profile for Dan  Send Email to Dan     
The original owner included a Prosport 12 --|328|51495|985|316472& id=185438

I don't know about these items. Should I just use the one I have?

My biggest question: is there a difference in the battery set-up for twin motors vs the set-up for single engine? This is why I asked about a third battery.

Dan posted 12-29-2008 11:13 AM ET (US)     Profile for Dan  Send Email to Dan     
Would I need/want:

Automatic Charging Relay (Starting Isolation)

http://|328|51495|316468& id=750182

Which of these switches should I consider?|328|51495&id=299265& start=01&results=10&sort=products

Should I consider a battery distribution cluster?|328|51495|316468&id=776726

Should I consider weatherproof breakers?|328|296553|299262|825433& id=812780

Thanks -- this CW reference article really helps:

andygere posted 12-29-2008 11:40 AM ET (US)     Profile for andygere  Send Email to andygere     
In my opinion, the BEP distribution cluster is the way to go. I'm using one on my Outrage 22 with a single 200 and a kicker, and it is flawless, a clean install and automatic. Turn the batteries on, run the boat, forget about the rest.
DeeVee posted 12-29-2008 12:28 PM ET (US)     Profile for DeeVee  Send Email to DeeVee     
I agree with Andy, the BEP switch cluster/automatic charging relay works nicely.

I run two electric downriggers on my Outrage 22 along with depth sounder, GPS plotter, VHF radio, stereo, running lights, two automatic bilge pumps, and a raw water washdown system. I have never had an issue on the water with this system in place.

I also have an onboard battery charger/maintainer to make sure the batteries are strong before we leave the house to head for the boat ramp.


glen e posted 12-29-2008 01:09 PM ET (US)     Profile for glen e  Send Email to glen e     
I have done several boats using Blue Seas ACR's - I like them. But if I had to do over again, I'd use the BEP cluster as they are simple. Do a search here for "bluewaterpirate" - he has some nice pics of his install.
bluewaterpirate posted 12-29-2008 02:42 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
Here is the BEP 716 Cluster I installed on my 210 Ventura.

Click to watch the slide show. s_id=2325387

Here is the BEP Cluster you could use for your application.


L H G posted 12-29-2008 04:14 PM ET (US)     Profile for L H G    
I think a lot of the discussion is this thread is overkill for an 18' boat with twin engines. For 22 years, I have operated an 18 Outrage with twin Merc 115's, each with it's own isolated battery system. As BW designed it, the starboard engine/battery also runs the house power. For that engine I use a dual purpose starting/Deep cycle battery. For the other engine, a simple starting battery will work fine, but you can also use the dual purpose battery if you want to connect a sonar/GPS or radio directly back to this battery. With the marginal alternator capacity on those Yamaha 70's (a puny 6 amps), separating high accessory draw items makes sense, as a combination of accessories could draw more than the alt puts out.

Whaler meant for the batteries on an 18 Outrage to be in the splash well, in their matching cases, and I think that's where they should be, as shown here is you scroll down a little. Mine sit on DryDeck pads.

Putting batteries in the console makes no sense to me at all. I cannot think of a single reason to do it. A lot of extra work, extra large gauge wiring, and expense for nothing, and you loose valuable console storage space.

The open configuration of a notched transom Whaler Outrage from this period does not lend itself to a lot of extra wiring configuration. I have never used or needed a battery selector switch, which I consider as more unneeded clutter. A three cylinder 70 is easy to pull start should it be needed, and a $10 pair of jumper cables works even easier.

I believe in keeps an open Whaler Outrage as clutter free as possible.

andygere posted 12-30-2008 04:23 PM ET (US)     Profile for andygere  Send Email to andygere     
Larry makes some good points about keeping the electrical system simple. A dedicated battery for each outboard, with one having shared duty for house loads is not a bad idea. Each could be configured with a simple on-off switch, and run as independent systems. If your boat can plane on just one of the two outboards with your typical load, you may well be just fine with that amount of redundancy. If not, making way at displacement speeds should one battery go flat may still be enough reliability. Three batteries seems like overkill for your set-up.

One very nice upside of the BEP cluster concept is that the batteries can be combined (effectively jump-started) with the twist of a switch. This sounds a lot better to me than rigging jumper cables on a rolling deck, or hoping to get that old carburated 2-stroke to fire up on a rope start. My experience is that these types of problems rarely occur in calm, controlled conditions. Use of the BEP 715 S takes the simple approach that Larry suggests, and adds the ability to quickly combine the systems to get both motors going if one battery dies. It also lets you handle house loads from either battery/motor combo, which is nice if you typically troll with just one outboard. I am sold on the BEP battery management clusters because they are compact, robust and they work! I mounted mine aft, just under the gunwale.

Final thought: The splash well is a fine place to mount the batteries on the Outrage 18, as it is on my '89 Outrage 22. There's plenty of room there, the battery boxes do a fine job of protecting the batteries, and you don't have all that copper cable running through the rigging tunnel just waiting to cause a problem some time down the road. Perhaps most importantly, you haven't sacrificed valuable and scarce dry storage space on the boat by filling the console with batteries.

Peter posted 12-30-2008 04:46 PM ET (US)     Profile for Peter  Send Email to Peter     
As rare as this may seem, I am in 100 percent agreement with Larry on this one. Even my 27 Whaler WD is set up similarly, each motor has a dedicated battery. The difference is that both batteries are wired to a selector switch so that house power can be drawn from either or both. It works and its simple.

My advice: Keep the high current wiring runs as short and as simple as possible.

Bulldog posted 12-30-2008 07:29 PM ET (US)     Profile for Bulldog  Send Email to Bulldog     
OK, I don't want to disagree with anyone but here are a couple things to consider:
1.) A good reason to move the batteries and wiring forward would be take weight from the stern and to remove batteries from a corrosive enviroment.
2.) Dan's batteries are already forward.
3.)Peter might already have a system as described in the reference section as "New dual engine" where a simple 27 dollar Blue Seas #6007 (1-off-2-both) switch would be hooked up as a dual pupose switch that would allow the house circuits to run from either battery and also would allow the house current to run from both while also tying them together to start a possible dead battery.
4.) Those 70 hp Yamahas are about 226 lbs each, anything new is about 100 lbs. more each. Whaler didn't design for heavy engines back then.
5.)Batteries have a "softer" ride at the stern which might prevent a failure.
6.)My Revenge, the battery cables can run under the gunnel away from the nasty tunnel, perhaps jacketed cable ($$$) would be better there. Tunnel makes for a long run to port engine.
7.)My boat is stern heavy with twin 70 hp engines and 8" setback brackets, stern seat and usually a couple people there also, my scuppers are under water when I have a full tank at half a tank sitting there they are above water line, moving 80lbs. of batteries forward on my boat will have a benefit to me.
8.) Larry and "Bucka" both have big engines on 18' Outrages with batteries in stern I belive. They have real world experiance.
9.) Never run twin engines any length of time with battery switch in both postion, not good for regulators, one will drive the other.
10.) Use the charger that came with boat, if it works.
11.) Larry, Andy and Peter are good guys, as a sort of newbie I haven't stepped on too many feet yet, but I'm moving mine forward....someday!
12.)It's your boat get as many views as possible then make a plan !...Jack
jimh posted 12-30-2008 11:47 PM ET (US)     Profile for jimh  Send Email to jimh     
On the battery location in the splash well or in the console, I'm more of a traditionalist and favor the splash well. But if someone has already moved their batteries to the console, I don't think you can talk them into moving them back to the splash well.

The beauty of simple systems is they're easily understood, easily maintained, and easily operated.

Peter posted 12-31-2008 10:15 AM ET (US)     Profile for Peter  Send Email to Peter     
Thanks to the pointer to the Reference section. My 27 Whaler WD is configured as shown in the "New" diagram. If I were wiring an 18 Outrage with twin outboards, I would do it with the same simple configuration.

Two batteries is plenty for an 18 Outrage.

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