Another Battery Question

[hostage]

Is it possible to run two batteries in this fashion:

1) Starter Battery that only is used to start and run the motor
2) Accessory Battery that is used for radio etc. (can be switched over if starter battery dies)
3) Both Batteries are charged by the alternator

Thanks,

Hostage

 

[jhebert]

Re: Another Battery Question

Yes. It is trivial to have two batteries and have them wired as you describe.

Your only requirement which requires some finesse to obtain is the ability to charge both batteries. There are two approaches to this:

--a single source of charging current is switched among the batteries to keep them both charged. The switching can be done manually or automatically. Or,

--a dual source of charging current is used, and each battery is charged simultaneous and independently.

If your engine battery charging system has only a single output, you must use the first method. If your engine has or can be modified to have dual charging outputs you can use the second method.

 

[Silvertip]

Re: Another Battery Question

Of course it is. Install a "dual battery switch" which is covered in a very high number of threads in this forum. Just search on "dual battery switch". They cost about 40 bucks right here on iBoats. The switch has OFF, BAT 1, BAT 2 and BOTH settings. The battery(ies) you have selected is what starts the boat, runs the accessories and will be charged by the engine.

 

[jhebert]

Re: Another Battery Question

To keep the house loads isolated from the engine loads, you must avoid the common OFF-1-BOTH-2 type of switch. These common switches will defeat your purpose entirely. I recommend you use a primary battery distribution switch similar to the BLUE SEA SYSTEMS 5511e model. More information from

http://bluesea.com/products/5511e

If you use a run-of-the-mill garden-variety battery switch you will not maintain the isolation you are seeking. Use caution when selecting the switch.

 

[Silvertip]

Re: Another Battery Question

Before we get into another very long discussion, let's make sure Hostage understands what he is really asking. Such as: 1) Does your application really require that the loads be separated?" Meaning is it really necessary to do this the way you "think" you need to. 2) Unless there is some underlying reason for total isolation of engine and house circuits, there is absolutely no reason you cannot use a standard dual battery switch. It is quite possibly the most inexpensive, versatile, and reliable solution to dual battery installations.
3) Exactly what are all the load you plan to run from the house battery? You only mention radio and "etc.". What are the "etc"? 4) When the engine is NOT running, you have the option of operating house loads from either or both batteries. You also have the option of starting the engine from either or both batteries. With the engine running you have the option of charging either or both batteries. It doesn't get more versatile than that. Just make sure you understand the difference between what you want to do and what is or is not necessary to do.

When we know that we can agree to disagree some more.

 

[jhebert]

Re: Another Battery Question

hostage:

Let me know if you need additional advice on how to manage isolated house and starting batteries and their charging. Will be glad to help. I have precisely that type of installation on my own boat. You can see all the details of the dual charging output installation, the isolated battery wiring and battery switch, and primary electrical distribution wiring at

http://continuouswave.com/ubb/Forum6/HTML/002758.html