Adding an extra battery?

[Esox]

I am considering adding an extra battery to power accessories instead of powering them from the starting battery. I do a lot of trolling with a kicker that doesn't charge my battery and I don't want to be stuck on the water with a dead battery after hours of trolling. I have room for a group 24 battery next to the starting battery. My plan is to add a Deep Cycle battery and connect all the accessories to it and leave the starting battery for just that, starting the engine. Is this the right idea or should I just get a larger starting battery?

 

[drewpster]

Re: Adding an extra battery?

You are definitely on the right track. I think it is necessary to have a second battery for safety. Here is a diagram you can used to add your battery. I added one to both my runabout and cruiser and have not had a dead battery on the water since. One great thing is that you can run all your do-dads without worry.

 

[imported_DANA1]

Re: Adding an extra battery?

nice picture, im checking over my battery system and need some clarification. what does arc stand for? and should my boat have a negative distribution point how do i identify it? thanks

 

[Boatist]

Re: Adding an extra battery?

Yes you got the right Idea. I like to leave all the gear you need to run the boat on the starting battery.

This includes Navigations lights, Blige pump, Bilge blower if you have one, Windsheild wiper, ECT.

For your second battery if you have a trolling motor or big amp stereo then get at least a Group 27.

If it is just GPS, depth sounder, VHF Radio that do not transmit to offten on then a group 24 works good for day trips. Multi day trips then you need a way to charge it.

If you want to be able to start off either battery without switching batteries then you will need to add a battery switch. With out a switch you would need to switch the positive cables between batteries.

 

[drewpster]

Re: Adding an extra battery?

ACR= Automatic Charging Relay
The system above uses an automatic relay that connects the batteries together automatically while the engine is running to charge them from a single alternator. When the engine is turned off the ACR detects the lower resting voltage of the batteries and disconnects them providing isolation between the house and start circuits.
The system is a bit more complicated than a simple 1-2-Both switch type system. However it provides complete isolation of the two batteries and simplifies things for the Captain.

Forget to switch from Both to number 1 when you get to the cove to anchor for the night and wake up with two dead batteries. It happened to me and I didn't like it. One bonehead move can ruin your weekend.

The negative distribution point can be anywhere the batteries ground together. My batteries both ground to the engine block. Some may ground to a common buss or plate then to the block as so on... Your battery most likely grounds to the engine. When you add your second battery just make sure you use a ground cable that is at least as large as the ground cable your start battery uses. You may be tempted to use smaller wire to connect your house battery to your accessories. I would advise against it. Use full size battery cables to connect your house battery to its switch and its ground. Keep in mind that you may have to use the house battery to start the boat. You need full size battery cables for that.

 

[Esox]

Re: Adding an extra battery?

Thanks for the great information and replies! Nice wiring diagram drewpster. This appears to be more involved than I originally thought.

My original plan was to add the additional battery just to run accessories without the ability to start the engine from it. Accessories I would be running on the second battery include 2 live well aerators, 2 gps/sonar graphs, interior lights, VHF radio, stereo and electric downriggers. I already have 2 group 31 deep cycles to run the electric bow motor so that will not be using the accessory battery. I wanted to keep it simple so I wouldn't have to bother with switching between different batteries. Right now I just have a power switch on the dash that cuts power to the accessories and a main switch next to the battery that cuts all power except the bilge pumps. Another thing is I don't think I have room in the engine harness to run an extra pair of battery cables to the outboard. I will have to double check that to be sure.

I was thinking of installing a battery combiner so both batteries will charge when the engine is running, but keep both batteries completely separate and just have a master switch for each battery. I hope this makes sense.

 

[drewpster]

Re: Adding an extra battery?

An ACR is a Combiner. Simple difference in terms is all.

The system above works without switching the batteries at all. Thats why it is designed the way it is. In normal operation both the house and start switches stay in the on position all the time. The parallel, or manual combine, switch stays off. Under normal conditions the switches would stay in where they are and the ACR, or combiner, does all the charging work. The reason for the three battery switches is to provide a way to turn off each battery individually. For instance, if you have a start battery that has a bad cell and will not stay charged you would turn off its switch and turn on the combine switch. This would allow the house battery to power the whole boat. Another example would be if for some reason your start battery goes dead, you would simply turn the parallel (manual combine) switch on. This will allow the good battery to boost the bad one and start the boat. The system simplifies things over a 1-2-both switch in my opinion. A 1-2-both switch works well if you are powering one system with two batteries. You simply select which battery you want to power the whole system. This system is set up to isolate two completely different systems each with its own battery.

The "start" battery system would only power the starter, the ignition and any gauges you may have. The "house" system would only power accessories, nav/anchor lights, radio and any other thing not related to starting or powering the engine.

You would have an automatic combiner to provide for charging the batteries while the engine is running. And a manual combine switch in case the combiner fails or you get a dead battery.

Like I wrote before, it seems complicated at first but once you set it up you can forget about it. And when something goes wrong you know you have it covered. I have been out there trying to fiddle with cables and monkey with batteries before and its no fun. This system in my opinion provides for nearly every eventuality.

See Link http://www.iboats.com/Mini_Selector....216621--list_time.1174607647--view_id.342283

 

[Esox]

Re: Adding an extra battery?

Thank's for the detailed clarification on your setup drewpster. It makes sense to me now. I do have one more question for you.

I looked at the "mini selector switch w/dual sense vsr" in the link you provided. Is that the "paralell switch" and "acr" in the diagram? If so it looks like I would just need to get that, another on/off battery switch, the battery and the tray to make this happen.

Thanks to everyone for the help. I hope to install the additional battery in the next couple weeks.

 

[tommays]

Re: Adding an extra battery?

Dude

that is NICE and gives some much better ways to add one to my boat this summer


Tommays

 

[ricksrster]

Re: Adding an extra battery?

I used a simpler method with an isolator. Doesn't matter if battery switch is off. Batteries will still charge. THe voltage drop from the isolator is insignificant,

 

[drewpster]

Re: Adding an extra battery?

Esox, The mini switch and VSR in the link I included can be used to add to your system. The switch is used to isolate the battery giving you a way to turn the battery on and off. The VSR is the same as a ACR. It uses the same setup as above except it does not include the third "parallel" switch for manually combining the batteries. The link below shows the proper wiring to install it.

http://www.bepmarine.com/products/inst-710-100a-vsr(web).pdf

You will need Adobe Acrobat to open the file.


rickrster's isolator setup also works well I am told. The voltage drop across the isolator is a matter for debate. It is a good example of powering one system with two batteries. Here is an opinion from a respected name in boating:
http://my.boatus.com/askexperts/doncasey/question.aspx?expertid=2&questionid=11721&cat=

 

[bruceb58]

Re: Adding an extra battery?

The voltage drop across an isolator is not insignificant. It results in a battery that is undercharged.

Isolators are old 80's technolgy. Newer installations are not using them anymore because of the undercharging issues.

 

[I/O WALDO]

Re: Adding an extra battery?

You can at the minimum install the acc.battery and connect the trolling motor and whatever other acc.you wish to it and connect the two battery grounds together and put an "on/off" switch in the pos. lead between the two batterys.Leave the switch on when running and off when trolling.And DUH,don't forget to use the switch,that is what they are made for!

 

[drewpster]

Re: Adding an extra battery?

I know the system I outlined seems complicated. The reason for all switches in a word is redundancy. This system is designed to provide battery power if their are failures in the system. (fire being a big one) I use my boat on a river. While I am always within reach of shore (swimming maybe), I travel many miles from home port. I have had failures at a distance from home that required calling for help and the cost is considerable. I would not recommend it for small boats one can simply paddle to shore. This system is designed for serious boaters who want reliability.

 

[Ship Wreck]

Re: Adding an extra battery?

In drewpsters diagram can someone explain the red wire from the alternator going to the house switch? The rest is understood....thanks

 

[bruceb58]

Re: Adding an extra battery?

Drewpster and I discussed that part of his drawing months ago. It really should just go to one of the batteries, preferably the start battery .

 

[drewpster]

Re: Adding an extra battery?

The red wire from the alt is it's charging wire. Normally this would connect to the start solenoid or the starter to provide charging.
In this system it connects to the load side of the house switch. It is done this way to provide a charging path from the alt to the house battery, through the ACR and to the start battery. This provides a means of isolating either or both batteries in the event of an emergency. If one battery has to be turned off it provides a manual means of charging the un-isolated battery through the parallel switch. It also gives a direct path from the alt to the battery that would normally have a greater state of discharge, the house battery.

 

[bruceb58]

Re: Adding an extra battery?

The only problem is that if you turn off the house switch while the engine is running, you will blow out your alternator...even if you are using the start battery to start your engine.

Drewpster, If I remember correctly, you have a large capacity ACR. Are you worried about a voltage drop across the ACR and cabling? I would think you would be fine hooking the alternator up to the start battery or the starter itself.

 

[drewpster]

Re: Adding an extra battery?

I am fine with it, and still on the fence about routing it to the house switch, frankly.
Personally I think that the designer is assuming that the engine ignition circuit will run from the fuse panel, thereby providing load in the event the house switch is accidentally switched off. I got no clarification on this but I will pursue it.
Another thing I remember is that ABYC wants total isolation of the batts for safety reasons. That means the ability to disconnect ALL loads. For that to be the case you would need a manual switch on the ACR to turn it off in that event. (my pathmaker has it, but not all others do)

 

[Tail_Gunner]

Re: Adding an extra battery?

there are some very knowledgable people posting here so is i may ask, is there a simple switch to buy that's damm easy to bolt up and the whole thing works?