Need info on adding a 2nd battery

[wlbolerdo]

I have a '92 70hp evinrude. I have a battery which, under a load, tested good. I have a battery switch which came with the boat(batt. 1, batt. 2 or both). I want to install a second battery, one for starting and perhaps the other for gauges and pumps. Any help would be great. Any diagrams or step by step would be awesome! I'm a little nervous because I just replaced my rectifier and tach and don't want to short out anything.
Wayne

 

[JCF350]

Re: Need info on adding a 2nd battery

Parts here.
http://www.iboats.com/Marine_Electr...ype.category--**********.345566964--view_id.5


Details here.
http://www.westmarine.com/webapp/wc...sor/10001/-1/10001/BatteryCombinersRelays.htm

 

[PondTunes]

Re: Need info on adding a 2nd battery

**Edit** If you just worked on the charging system do you know what amperage it outputs?

Unless it's way up there your 70 hp rude isn't going to have enough juice in the charging system to use a combiner / isolator to keep 2 batteries charged. Your best bet would be to leave your system wired as is, and install the second battery as a backup. Always use battery #1 for starting and buy the biggest deep cycle you can get for battery #2.. Then use it when you're running the electronics and keep battery #1 reserved only for cranking.

The charging systems on outboards are designed to keep a battery topped off and trying to use them to bring one or more batteries back from a discharge state would take a very long time at WOT.

In this example battery #1 (Starting / Deep Cycle) is connected to position #1 on switch "A" (1/2/off/both) your starter/alternator/electronics are connected to the common post on switch "A". Battery #2 (A large deep cycle, group 27, 31 etc) is connected to position #2..

Normal operation, crank up the boat on battery #1 and drive to wherever you're going to swim/fish/anchor. Shut down the motor and switch over to battery #2 (previously charged before you left) and use it to run the radio, fish finder, trolling motor or whatever. If it goes dead you can always switch back to battery #1 to crank the engine.

Once you get back home put both batteries on a charger, you can get a marine charger that stays in the boat that will simplify things by allowing you to just plug it up and it will take care of the rest!

 

[JCF350]

Re: Need info on adding a 2nd battery

Now we have a simple diagram on the site. How about a sticky for this.

 

[por2gezo]

Re: Need info on adding a 2nd battery

House Loads = Alternator right ?

 

[flargin]

Re: Need info on adding a 2nd battery

House Loads = Alternator right ?

House loads are like lights and stereo, trolling motors etc.

I thin we should collect all of the diagrams and create a sticky

 

[Silvertip]

Re: Need info on adding a 2nd battery

You have a misconception about how a switch is used. First -- there are two electrical systems on a boat. 1) the engine harness runs from the engine to the front of the boat. It gets its power from the two large battery cables connected to the start battery. That power system feeds the ignition switch and powers the gauges when the key is turned on. So issue #1 in your plan is you do not disconnect gauges from that circuit put them on another battery. You have no way to turn them on and off unless you add yet another switch which is simply a nonsense approach. Putting other stuff on the "house" battery is certainly a valid plan but then you don't need the switch to do that. 2) The second system in the boat is the two smaller wires that run to the circuit breaker or fuse panel in the boat. It is this circuit that powers everything else in the boat. Now then, there are many ways to wire a switch but it all boils down to "protecting the start battery" is it not? Well then, the best way to do that is wire everything to the COM terminal on the switch. You then have the option of switching to BAT 2 when parked which prevents draw on the start battery. Underway you can set the switch to 1, 2, or both to charge the selected battery or batteries.
Here is a simple wiring diagram for a dual battery switch. All loads get connected to the COM terminal. Note that all cables in this diagram must be the same gauge or larger than the regular battery cables. Wires feeding the loads need only be sized appropriately for that load.

 

[Fun Times]

Re: Need info on adding a 2nd battery

Also if any one would like to add a thrid battery to twin engine boat with out a isolator, Here is a good way to do that. If you have 3 batteries and 2 switches, And 2 engines. This is A good way to hook it up.

Switch position 1 on both switches goes to a battery for each engine.

Switch position 2 on both switches goes to the Stereo/3rd battery.

This way if you turn both switches to ALL, all 3 batteries are connected. As long as you have 1 charged battery, you can start both engines.

The only thing you can not do is run both switches on # 2 when the boat is running or both engines would be charging the stereo battery and they don't like getting that many chrging amps at once.You could run a big deep cycle battery for the stereo, You would turn both switches to 2 when sitting in a cove And playing the stereo for a long time with engines off, That way the stereo will only draw off the 3rd battery. Also when you are on a long cruise you will want to run One battery switch on #1 and the other switch on [ALL]. It make no difference which switch is on 1 and which is on ALL. Just make sure you varry the switches and charge the stereo battery as needed by Just setting A Battery switch to number 1 on one of the switches, And set the other switch to ALL to charge all three batteries at the same time.

Your other option is to run a battery isolator.

 

[CharlieZulu]

Re: Need info on adding a 2nd battery

When running the boat in BOTH, how do I know my motor has enough juice to charge both batteries? Is it OK to do this, or am I in danger of stressing the switch box on the motor>
(90 hp 1987 O/B)

 

[diverboybrent]

Re: Need info on adding a 2nd battery

You have a misconception about how a switch is used. First -- there are two electrical systems on a boat. 1) the engine harness runs from the engine to the front of the boat. It gets its power from the two large battery cables connected to the start battery. That power system feeds the ignition switch and powers the gauges when the key is turned on. So issue #1 in your plan is you do not disconnect gauges from that circuit put them on another battery. You have no way to turn them on and off unless you add yet another switch which is simply a nonsense approach. Putting other stuff on the "house" battery is certainly a valid plan but then you don't need the switch to do that. 2) The second system in the boat is the two smaller wires that run to the circuit breaker or fuse panel in the boat. It is this circuit that powers everything else in the boat. Now then, there are many ways to wire a switch but it all boils down to "protecting the start battery" is it not? Well then, the best way to do that is wire everything to the COM terminal on the switch. You then have the option of switching to BAT 2 when parked which prevents draw on the start battery. Underway you can set the switch to 1, 2, or both to charge the selected battery or batteries.
Here is a simple wiring diagram for a dual battery switch. All loads get connected to the COM terminal. Note that all cables in this diagram must be the same gauge or larger than the regular battery cables. Wires feeding the loads need only be sized appropriately for that load.

If you have a set up like this how would you charge your battery's with a charger do you have to disconnect before charging, or can you just hook up and charge away? and if you have two different battery's would be the go there for IE a sealed and a lead acid?
I have the main battery connected up to everything and its my start batt but would like to put a second deep cycle to run when the boat motor is switched off.
What do you recommend i do

 

[Big Pete]

Re: Need info on adding a 2nd battery

On charging from a standard mains charger you would simply click the battery selector to off and connect and do each battery as you would on your car etc..

well thats what i do anyways , unless someone has better way ..