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Need help and advice....

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RedRedWhine
Navigator

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USA
167 Posts

Initially Posted - 07/24/2008 : 16:12:35

As you all may know I have been working on Red Red Whinefor about a month now. Well I am trying to set up dual batteries and run that to a switch for Both, Bat 1, Bat 2 and Off. I am looking for infor and a diagram if anyone has one. I need to know how to hook up the batteries so they are 12V not 24V and where and how the engine power cables come in at on the switch. I am also adding a second breaker panel so I can add other items like a Chart plotter, cigarette adapter, fan etc. Any advice and pictures would be great. I had someone helping me but he had to go out of town and I need to finish this myself. Thanks or all the help.

Don and Kim Young
Las Vegas Nv
http://web.me.com/bolter303/Our_World/Welcome.html

Edited by - on

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 07/24/2008 : 17:40:55

Are you sure you want a switch and another panel? I kept my electric system simple. Two 12V batteries connected to each other. Positive terminal to positive terminal and negative terminal to negative terminal. That keeps it at 12V and doubles the Amps. My outboard power cable runs right to the battery. Ditto for the main cable to the breaker panel. Ditto for the charger. Same simple system as a one battery setup but with twice the amps. I ran my GPS Chartplotter, VHF, Depth/Speed to the Accessory breakers on the panel. You can double up on them.

Edited by - on

Sloop Smitten
Master Marine Consultant

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USA
1181 Posts

Response Posted - 07/24/2008 : 17:47:29

This might help.

[url="http://www.diynetwork.com/diy/bo_maintenance_repair/article/0,,DIY_13718_2277960,00.html"]Marine Batteries: Installing the Battery Switch and Wiring the Battery[/url]

Remember, only the hot wires go to the switch. The negative wires are jumpered together and go to either/or to your grounding buss bar or negative wire from your engine.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 07/24/2008 : 20:50:54

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Nautiduck
 I ran my GPS Chartplotter, VHF, Depth/Speed to the Accessory breakers on the panel. You can double up on them.<hr height="1" noshade id="quote"></blockquote id="quote">My boat has a bus-bar wired to the Accessory switch/fuse so each of those devices has a separate connector. Flip one switch and there's power to all my nav electronics. I have a dozen switches as it is. The 12v plugs aren't switched, although they're fused... I guess the assumption is you can just unplug something if you want.

If you go Randy's way (which is reasonable on a small sailboat), all you need is + to + and - to - on the batteries, and then wire your engine and your house power to either battery. A fuse for the house power, close to the batteries, is recommended. An on-off battery switch there is also not a bad idea. But remember, with that simple configuration, if one battery gets weak (unlikely), it'll take the other with it. Correspondingly, if you replace one, you should replace both with identical batteries.

Edited by - Dave Bristle on 07/24/2008 21:04:04

RedRedWhine
Navigator

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USA
167 Posts

Response Posted - 07/24/2008 : 23:10:35

Hey guys thanks for the quick responce. Here is what I have:
I set up two battires that are hooked + to + and - to -. Than I ran the + to the switch at Bat 1 and Bat 2. Than the ground - from the battries go to a bus that is attached at the inside of the back of the rear bulkhead panel. I added a new electical panel on the rear bulkhead as well. I will attach to this panel the bilage pump, chartplotter and a cigrette lighter for charging cell phones and such. The + on both electical panels go to the COM on the switch and the - goes to the bus. Than I attach the hot of the pump to the hot on the panel and the neg to the bus. The hot of the outboard goes to the Com and the Neg goes to the bus.

Let me know if this sounds right. I did this today and the cigarette lighter worked and the panel lights all came on. I think I am good. I am just wondering if all this stuff going to the bus is correct. Am I overloading it? What is the correct way to ground the boat and electrical system.

The reason I added the extra panel is because the other is full and I did not want to overload it. I plan to have it all done by this weekend.

I got my new Bimini today and I will send pics when it is installed. Thanks for all the help.

Edited by - on

OLarryR
Master Marine Consultant

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USA
3436 Posts

Response Posted - 07/25/2008 : 05:32:07

I read somewhere, maybe the 12 Volt Bible, that hooking up two batteries actually does not provide twice the amps. That is, if you hook them up together with no switches. It supposedly provides around 40% more amps. If you utilize a battery switch and were in the habit of using each battery separately and charging each battery separately, then you would have twice the amps. One problem with hooking the batteries up together is that if one is or becomes weaker than the other, then it draews down the capacity of the stronger battery. That is why they sell battery isolators and combiners which separate the batteries while still having both in the circuit. But this then moves you further away from a simplified circuit which is what you want to install.

I have two batteries with a battery switch but have not gone the battery isolator or combiner route and may not ever. The negatives, as others indicated, are jumpered together. then the positive of each battery goes to the separate positives on the battery switch. the outboard positive can go to the battery switch positive that allows switching from either '1" or "2" or "both". Even if I do not get twice the amps, the boat came with the dual battery setup and does provide more capacity that way. In practice, I do not use the battery switch. I mostly leave it in the "both" setting rather than being concerned with switching between "1" and "2" and sometimes forgetting to do that or switching when the outboard is running and possibly goofing something up with it's charging system. I have a solar panel that is direct connected to both batteries and that could be improved as well, if I were to have diodes or separate panels for each battery so that each gets max benefit out of the charging. But I find that my batteries have maintained a full charge now for over almost 3 years and the batteries were not brand new when I bought the boat, so I figure my present setup is doing fine as far as I am concerned...and I have moved onto other projects.

Back to one of your original questions...does someone have a diagram of the setup ? The catalina Tech manuals located elsewhere in this Forum has a section on batteries (ie. the post '88 manual) and it has several battery schematics. One is listed below...but you can access it thru the manuals as well.

Edited by - OLarryR on 07/25/2008 05:35:45

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 07/25/2008 : 09:33:13

Combining batteries in parallel (+ to + and - to -) definitely does double the amps (Boatowner's Illustrated Electrical Handbook).

Again, I ask why the switches?

My battery approach is buy two quality identical AGMs, combine them in parallel, go sailing.

Edited by - Nautiduck on 07/25/2008 09:41:51

Sloop Smitten
Master Marine Consultant

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USA
1181 Posts

Response Posted - 07/25/2008 : 10:07:25

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Again, I ask why the switches? <hr height="1" noshade id="quote"></blockquote id="quote">

I believe the main reason for keeping the batteries separate is so you have one battery dedicated to starting the motor. That way if you are running your electronics and your battery drains you still have one battery in reserve to start your motor. This is more critical in applications where you do not have an outboard that can be started with a pull-cord. I have my batteries set up like Nautiduck but do not have an electric start outboard. Actually I have the switch in place also but it is wired as RedRedWhine is so there is no isolation between the two batteries. I use the switch to disconnect the batteries when they are not in use.

Edited by - on

OLarryR
Master Marine Consultant

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USA
3436 Posts

Response Posted - 07/25/2008 : 11:12:09

Randy,

Combining the 2 batteries in parallel does give twice the amps initially but that implies to many that the batteries will last twice as long/have twice the capacity. I will have to check at home for the reference where I read that it really only works out to about a 40% increase in capacity over the actual use and long term. I think it has to do with each battery not exactly at same capacity level and then charge up at different rates....but I am not sure. As with you, I am only stating what I read and apparently since you have read something different, then there apparently is debate over just what works out in reality. I will try and find the reference ...believe it was the 12 Volt Bible. If anything, it will at least uncover some uncertainty and also provides validity as to why some install battery combiners and isolators to ensure they get max out of there dual battery setups. But like I said, I have the dual battery setup as well and feel it is worthwhile having it.

Edited by - on

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 07/25/2008 : 13:12:09

Larry, from what I can read this is one of those things that can go either way and be fine. Some level of isolation can prevent one bad battery from impacting another good battery. My philosophy is that going with two new AGMs makes that very unlikely so I am OK with the simpler setup. Others will want to go the other way. It's all good.

I do have electric start outboard but still this is not like the way that bigger boats handle things. They have a separate battery bank that is geared to starting their diesels (batteries with high cranking capability). My Honda is fine to start with the AGMs that are built for long lasting steady power. But again, it can be argued that isolation would help prevent a situation where the batteries would both fail and not be able to start the OB. I do have a pull cord but am now so used to the electric start that I don't think I could pull the cord!

OK, I do pull start once a season just to make sure it still works.

Don, you are doing lots of work on that boat. I hope you are taking pictures. Things like electric setups are always being asked about. People will want to see yours.

Edited by - Nautiduck on 07/25/2008 13:13:30

OLarryR
Master Marine Consultant

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USA
3436 Posts

Response Posted - 07/25/2008 : 13:33:34

I agree with all that you have said. Coincidentally, i also have a Honda w/electric start and am getting fine life out of both batteries without an isolator or combiner. Just that like all of us, we read about these gizmos that are made to improve reliability... but i am doing fime without an isolator or combiner so it is low priority if any.

Edited by - on

Dave Bristle
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Djibouti
10005 Posts

Response Posted - 07/25/2008 : 13:47:00

Joe is right--Sarge is a case in point. I run with the switch on Both... then when I drop the hook for the night, I switch to 1 or 2 (alternating from night to night), to be sure the other battery can start the engine the next day. The engine is the 3.5 litre V6 from the Honda Pilot--no pull-cord!

One reason for putting a selector switch on in your case is to be able to select one battery to charge with your lower-power alternator, to bring it up faster. Otherwise, simple is good.

Edited by - on

RedRedWhine
Navigator

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USA
167 Posts

Response Posted - 07/25/2008 : 14:14:27

Hey

Thanks for all the info. I feel better now that I see I attached everything right. The main reason for the switch on the dual batteries was because I wanted a way to shut everything off when I am not on the boat. I also wanted more AMPs for longer stays on the boat.

Randy, yes I have taken lots of pictures and I will sit down soon and put them all together in detail.

I guess the question I still have is what is the correct way to ground the boat. Is the way I did it to a bus bar correct and OK.

Thanks for all the help

Edited by - on

Sloop Smitten
Master Marine Consultant

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USA
1181 Posts

Response Posted - 07/25/2008 : 15:10:40

Don,
It sounds like your grounding scheme is correct. You join the two battery ground terminals together and run a single ground cable to the buss bar from one of the batteries. All accessories should then be grounded to the buss bar with the possible exception of the engine ground which you may want to ground directly to the battery.

Edited by - on

frogger
Navigator

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USA
184 Posts

Response Posted - 07/25/2008 : 17:06:13

Agree with Nautiduck. Connect the two batteries in parallel, hook up to a solar charger, and sail. I just had to replace both of my batteries, but then they did last 7 years.

Edited by - on

RedRedWhine
Navigator

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USA
167 Posts

Response Posted - 07/25/2008 : 22:50:28

Joe,

Sounds good that is how I did it. I just grounded the engine to the battery and all other grounds to the buss. All worked great today. Now just clean up. I was wondering if anyone else had a problem with water under the holly deck not draining into the bilage. I had this problem so I removed the deck and found that the water would not drain between the holly and the fiberglass floor. I drilled about a dozen holes in the deck under the floor, no more problem. I hope to have her back in the water Sunday or Monday.

Edited by - on

SEAN
Admiral

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USA
772 Posts

Response Posted - 07/26/2008 : 20:29:27

I have my batteries in parallel , I dont think a pull start motor needs its own battery .

I have one switch to shut everything down .

the battery monitor and bilge pump is wired straight to the battery .

thats how my set up is , I pretty happy with it .

I forgot the fuse 1 before each switch

Edited by - SEAN on 07/27/2008 11:46:45

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