Adding an extra battery?

[drewpster]

Re: Adding an extra battery?

Mount a second battery paralleled with first. In the positive cable between the two batteries place a high amp SPST switch. When you shut down at anchor turn the switch to off isolating the second battery. It works but it does not offer the redundancy or convenience of the three switch system.
And remember, if the first battery runs dead the second battery will have to overcome the load of the dead one when it is turned on. Ever try to boost a car using only a battery and jumper cables? Doesn't always work.
1-2-both systems are a little better and only slightly more complicated. The allow the entire electrical system to be switched to a fresh battery while the "Both" position is used for charging. This is the system I was using when I ran dead 40 miles up river. I accidentally left the switch set to "Both". After catching myself forgetting it often enough, I decided I needed a change.
TG, In lieu of using the three switch system, 1-2-Both setups are simple and they work, you just have to remember to flip the switch at anchor.

 

[bruceb58]

Re: Adding an extra battery?

Just get a 1-2-Both switch. get a combiner to allow both to charge. Only use the Both position in an emergency when you need both batteries to crank the engine but return the switch to either 1 or 2 after it is started.

 

[drewpster]

Re: Adding an extra battery?

Bruce's 1-2-both/ combiner is an even better idea than the switch alone. I think I will use it in my tri-hull to save a little space.
After building the switch panel I am using for my bigger boat I think I would be better off using the 1-2-B switch in the runabout to save a little space. It never goes as far from home as the bigger boat does anyway.

 

[Bonus]

Re: Adding an extra battery-another alternative

Re: Adding an extra battery-another alternative

Another good alternative to the ?ideal? three switch model described by Drewpster; (found on the West Marine site at: http://www.westmarine.com/webapp/wc...sor/10001/-1/10001/BatteryCombinersRelays.htm

is the New Blue Sea Systems ?Dual Circuit Plus Battery Switch? it is described on the same web page below the drawing that Drewpster shows. This is basically a dual pole batter switch placing both the individual house and start battery shut offs in one device with the ?plus? function of allowing you to combine the batteries for low battery starts.

To quote the West Marine site (below the drawing presented previously): ?A simpler alternative to isolate your Start and House circuits (minus the other benefits of a three-switch system, is available in the Dual Circuit Plus Battery Switch (Model 7808801) (Blue Sea Systems model 5511e -Ed.). In the ON position, it keeps your batteries isolated, so both can't be fully discharged by accident. In the COMBINE position, it parallels your batteries in the event of a low Starting battery. Used with the BatteryLink ACR, it automatically combines or isolates your batteries when in the ON position.?

I'm not smart enough to paste a picture here but this will take you to the swich on the West Marine site; I have seen them marketed elswhere with Blue Sea Systems ACR in a "add a battery" package as well.

http://www.westmarine.com/webapp/wc...8801&y=20&x=10&storeId=10001&ddkey=SiteSearch

To me this is what I have been looking for a simple runabout. You can?t turn off the house or start individually, but turning everything off and on is simply one switch, and the "jump" circuit is built in" I have not installed this yet on my current boat but will order this weekend. It will be part of the add a dual battery project on my 88? Concord.

Bob in CO

 

[Tail_Gunner]

Re: Adding an extra battery?

http://www.iboats.com/Attwood_Batte...d.216621--list_time.1178388634--view_id.47115

Is this the type of switch that you are referring to??

 

[bruceb58]

Re: Adding an extra battery?

That is it.

 

[Bonus]

Re: Adding an extra battery? - Dual Systems

Re: Adding an extra battery? - Dual Systems

Tailgunner (and/or Bruce, if you were agreeing for me) That is Not the type of switch I was referring to; that is the old fashion “two batteries, one load” aka:Single Pole-Double Throw switch. Thought by many as inferior to the “three switch” setup

I was referring to a different (new) model “two batteries, two loads" or Double Pole-Double Throw. Although each can combine both batteries; the old school double switch does not provide for separate house and engine circuits, it is really for one load, start/engine. (as described previously) The switch I am referring to (Blue Sea Systems Dual Circuit Plus-5511);provides the functionality of the three separate switch setup in one device, with the only difference being you shut off (and on) both the house and starting circuits with one action; which is fine for many simple marine setups.

This shows it in “schematic” with a ACR charging circuit; together it makes a good combination for adding a separate house circuit.

Bob in CO

 

[bruceb58]

Re: Adding an extra battery?

I agree, that is a better switch if you want to have a seperate house battery for running all electronics on seperate from a start battery. For my application, a 24 foot cuddy cabin boat, it isn't worth the trouble to seperate out to a house battery/start battery configuration. I pretty much run everything off one battery and the second battery is my reserve.

Now, I don't have any "heavy hitters' power wise, so what is good for me may not be good for you. If I had a fridge or an inverter, it would be a different story.

 

[I/O WALDO]

Re: Adding an extra battery?

Mercruiser says there should be NO switch between the start batt.and the engine on a computer equipped efi engine.

 

[drewpster]

Re: Adding an extra battery?

Waldo mentions something interesting. All the configurations described in this thread should work fine with engines having conventional controls. (ignition, injection ect.) I wonder what is needed in a boat with newer more complicated engine controls? I have not heard of an ECU (eng. control unit) computer having a problem from losing battery power. If that were true you would have computer problem every time a battery went dead or changed one. However needing a constant power source connected to Merc may not be because of the computer. Do you know why Merc says not to use a switch? This would also seem to be contrary to what is required by ABYC as well.

 

[rmurray]

Re: Adding an extra battery?

Couple more questions...

When running the motor with two batteries in "Both" position without an isolator/combiner installed, will a more discharged battery still pull from a more charged battery or does this only happen when the motor is off? I want to use the "Both" position only to charge the batteries with the motor running, but I don't want one pulling from the other.

How can I tell the difference between a combiner and an isolator? They are both relays? I think I want to go with a combiner, but they both share similar terminology (battery, charging, relay, etc...). I want to make sure I get the right one!

 

[bruceb58]

Re: Adding an extra battery?

If you have the switch in the both position while the engine is not running, the battery that is more fully charged will supply current to the discharged battery until the voltage of both batteries are equal.

When the boat is running, both batteries will charge but the battery that is more discharged will receive more current.

A combiner uses relays that are energized when the voltage of either leg reaches a certain voltage limit, thereby only connecting when the alternator is outputting.

Combiners use relays and isolators use diodes. Diodes will cause a voltage drop between the alternator and the battery which will not allow your batteries to fully charge.

 

[rmurray]

Re: Adding an extra battery?

Has anyone had any experience with a Hellroaring Isolator/Combiner?

http://www.hellroaring.com/marine.htm

They sound great on paper. Any feedback is much appreciated. Thanks!

 

[bruceb58]

Re: Adding an extra battery?

I would suggest this one:

http://bluesea.com/category/2/products/7600

 

[Ship Wreck]

Re: Adding an extra battery?

Drewpster, I am installing your system this week. In your diagram on either side of the acr , are those fuses and if so what size.
Also, I don't seem to have the common ground point in the diagram, I know I have a main ground point somewhere, could it be the outboard engine? The engine ground runs to the battery negative terminal and then a ground wire runs to the house bus negative bus bar. Any thoughts.
Finally, the red wire from the alternator? I don't currently have this wire? Is this something That might be implemented in my engines Positve termial feed? If not then I have no idea where to install this red wire on the engine?
can you try and simplify this wire...?
Thanks....

 

[ricksrster]

Re: Adding an extra battery?

Gentlemen:
A clarification. I'm using an isolator on an unregulated system. My voltage drop is less than one volt. It went from 16v to a little over 15v. My batteries get fully charged.
I can see with a voltage regulator the voltage would probably drop to under 14v and the batteries would not fully charge.

 

[drewpster]

Re: Adding an extra battery?

Shipwreck, Sorry for the delay. The main ground point in your system is the engine. The ACR you use should recommend the proper place to ground it in its instructions. This would normally be at the negative buss bar you mentioned or possibly at the batteries depending on where you mount the ACR.
The red wire shown in the diagram is a charging wire that supplies charging voltage to the batteries. I cannot say exactly how you should connect it without knowing your engine's charging system. It is important to become familiar with how your outboard supplies power back to the batteries and how the charging system works. Especially if you are completely isolating house and start loads. I recommend buying an engine manual for your engine.
The idea is to completely isolate the starting circuits from everything else and connect the charging wire in such a way to supply charging to either battery independently or to both through the ACR or the parallel switch. This provides redundancy in the event of battery failure or ACR failure, or both. (like fire or dead battery cell) NOTE: NEVER switch the batteries to OFF while the engine is running! This will damage the charging system. (I prominently labeled the face of the switch panel to remind me never to switch to off, I suggest you do the same)
The diagram shows interrupt protection in its cables to protect the cables in the event they become overheated. The rating of the fuses or breakers depend on the amp rating of the ACR, the size (gauge) of the cables, and the length of total circuit run. My ACR has an option built into it that allows the ACR to be manually closed. This means I can use the switch on the ACR to temporarily combine the batteries in the event of a dead start battery. This makes the ACR a part of the STARTING circuit and hundreds of amps can pass through it while starting the engine. Therefore I do not use fuses or breakers in its cables. I can do this safely because I am using large battery sized cables to connect it, and the ACR itself is rated to carry the load of starting the engine. It is also placed very close to the batteries so I do not have long cables.
Some ACR are not rated for starting currents and are used for CHARGING only. These types do not normally have the 'manual override' feature. If they do, and they are not rated for at least 150 amps, they should not be used to start an engine with a dead battery. They should be used for charging only. Fuses should be used to protect the cables and the ACR at each battery for this type ACR. The ACR should come with instructions on the proper gauge cables and fuses to use. Some ACR's come with the cabling already attached with the fuses installed. (if you need more help on this, give me some more info on your setup)

 

[drewpster]

Re: Adding an extra battery?

I wanted to also add that the diagram I used as well as the engineering behind it are not my own. I learned about this system from several sources and researched heavily before deciding to use it. The diagram itself is from another website and competitor of the iboats website. Out of respect for iboats I will not mention it here. I take credit for sharing the information only. I believe this is the best system for my needs and I personally recommend it but I cannot, and do not, take credit for its design. Drew

 

[Ship Wreck]

Re: Adding an extra battery?

Drew, I do appreciate all of your input.
As I get more involved I am thinking that your system is more than I need.
I have a 20 foot trophy that I run not off shore.
My main concern is having backup starting power if needed. I could care less about long trips with loud music.
When engine is off I only use GPS and radio sometimes.
From this descritption would a 1 2 both switch be a better thought for me.
If so, is there a good diagram of how to install this set up.
And my understanding is 1 from 1 battery 2 from 2 battery both from both battery. Only question being is does charging of both batteries only happen in the both postion........

 

[bruceb58]

Re: Adding an extra battery?

All you need is the 1 2 Both switch and an ACR so that you don't have to put in "Both" to charge. You will only use the "both" position in the hopefully rare occurence that you would need the power of both batteries to start your engine.