Adding an additional battery

S

Slacker

Member
Apr 23, 2008
143
Oxford, CT
Boat Info
2006 Searay Sport 205 w/ Monster Tower and Kicker Amp.
Towing w/ 2018 Mercedes GLE350
Engines
Merc 4.3L MPI Alpha (220hp)
I'm sure there is a thread on here somewhere, but I couldn't find it so I'm going to ask.

I just installed and amp, so now I definitely fear running out of battery if using the radio when the motor is not running.

Can someone recommend a dual battery kit, or let me know what parts I need to purchase in order to add the second battery? I am pretty good when it comes to wiring so I'm assuming this is something I can handle installing myself...

Thanks in advance!
 
Nothing to fancy here. Just need a dual battery switch ~$40 -$50. Then you'll need (2) more "+" cables to go from the batteries to the switch. If your current "+" cable won't reach where you mount the switch, you'll need a longer one. Then you'll need a short "-" cable to tie the two "-" posts together, using the screw posts. Last thing will be another battery tray.

(2) "+" cables (posssibly 3)
(1) "-" cable (if batteries are next to each other, about 12"-18")
(1) Tray
Appropriate mounting hardware and cable ends
 
I use one of these:

http://yandina.com/c100InfoR3.htm

All automatic, you don't ever need to remember to turn any switches.

And simple, simple hook up. There are 2 red wires coming off the combiner, put one on each battery. Put the black wire on the starting battery and connect the 2 battery grounds together with a short jumper. DONE.

Here is the installation manual:
http://yandina.com/acrobats/C100Data.pdf

You can even put a battery charger on the starting battery when the boat is parked. The combiner will regulate the charger and maintain the charge on both batteries automatically.

If you ever want to add another battery, no problem - just add another combiner.

Check your alternator amp rating. This combiner is good to 100 amps. They have bigger combiners if you need them.
 
My second battery (house battery) which I plan to use for stereo equipment should be a sealed deep cycle battery correct?
 
SeaRay said:
I use one of these:

http://yandina.com/c100InfoR3.htm

All automatic, you don't ever need to remember to turn any switches.

And simple, simple hook up. There are 2 red wires coming off the combiner, put one on each battery. Put the black wire on the starting battery and connect the 2 battery grounds together with a short jumper. DONE.

Here is the installation manual:
http://yandina.com/acrobats/C100Data.pdf

You can even put a battery charger on the starting battery when the boat is parked. The combiner will regulate the charger and maintain the charge on both batteries automatically.

If you ever want to add another battery, no problem - just add another combiner.

Check your alternator amp rating. This combiner is good to 100 amps. They have bigger combiners if you need them.
Click to expand...


Wow awesome! This is a great idea! So basically if I hookup my amp and radio to the non starting battery I can run that one dead, and still start the motor with no issues?
 
I just called them to ask a few more questions and was told it comes with all the needed wires, etc. as well. So I would only need the tray and battery if I went with this setup? Love it!
 
Isn't the alternator on our boat rated at 120amps though? So you would need to buy the larger version that handles up to 150amps? I hope I'm wrong because it's an additional $100.
 
Have a look at Blue Seas "add a battery kit" as well.

http://bluesea.com/products/7650

They are listed as being ignition protected and UL CSA approved while the previously mentioned one was not.

The Blues Seas kit is available almost any where even ebay. Just google it and you will find alot of vendors.
 
I recently had this done at a local boat service place. $400 with battery.

Now I can go from Bat 1 to Bat 2 or even pull from both Bats
 
I am on my way now to the marine place near my work. I decided to go with the battery switch instead. The automated one is just one more thing that can break and send me drifting into rocks because I can't start the boat... we don't want that. Not to mention cost. It would be over 300 for the blueseas sytem with the battery, versus under 200 with battery for the switch. Just have to remember to change it when I'm hanging out listening to music or I'm screwed. Thanks for the help guys! I will let you know how the install goes.
 
I'm not discounting the Blue Seas system - it has it's benefits. But for $100, I'll manually turn a switch all season long and be happy about it!:smt001
 
Sorry for the late response...

Your alternator should only be about 65 amps.

I have a 5.0L MPI and that's all mine is.

Yes, it comes with everything you need but the short jumper battery cable you need to connect the battery grounds together.

When I bought mine I did some research and there are VERY few units that ever get returned. And the ones that do, are usually fine they were just wired incorrectly.

I think there is less chance of screwing something up with this versus a switch. From my understanding, if you ever run your boat with the switch off that is really bad news.

I don't want to worry about selecting a switch position, with three kids on board and my wife I already have plenty of other stuff to worry about!!

I am running three amps off of mine, with no problems.

Worst case, the stereo battery amperage drops too low for tunes. The boat will still start so fire it up, cruise around a little then go back to floating and listening to tunes.
 
I used the Blue Sea Add a battery kit which I picked up for under $90. The additional battery cables to connect to the switch and combiner I had custom made to length for under $60 at http://genuinedealz.com/. I picked up a Marine battery at Costco for $60. Installation was relatively easy in about an hour.
 
Question... I see in the diagram for all of these you need the control wire. I haven't looked for it in the manual yet, but is this wire east to locate? What is the additonal wire that is on my battery come from? Minus the one I just added for the amp I installed...
 
SeaRay said:
I use one of these:

http://yandina.com/c100InfoR3.htm

All automatic, you don't ever need to remember to turn any switches.

And simple, simple hook up. There are 2 red wires coming off the combiner, put one on each battery. Put the black wire on the starting battery and connect the 2 battery grounds together with a short jumper. DONE.

Here is the installation manual:
http://yandina.com/acrobats/C100Data.pdf

You can even put a battery charger on the starting battery when the boat is parked. The combiner will regulate the charger and maintain the charge on both batteries automatically.

If you ever want to add another battery, no problem - just add another combiner.

Check your alternator amp rating. This combiner is good to 100 amps. They have bigger combiners if you need them.
Click to expand...


Does anyone know the difference between a "Combiner" like the Yandina and an "ACR" like the Blue Seas? Are the terms and functions interchangeable?
 
SeaRay said:
I use one of these:

http://yandina.com/c100InfoR3.htm

All automatic, you don't ever need to remember to turn any switches.

And simple, simple hook up. There are 2 red wires coming off the combiner, put one on each battery. Put the black wire on the starting battery and connect the 2 battery grounds together with a short jumper. DONE.

Here is the installation manual:
http://yandina.com/acrobats/C100Data.pdf

You can even put a battery charger on the starting battery when the boat is parked. The combiner will regulate the charger and maintain the charge on both batteries automatically.

If you ever want to add another battery, no problem - just add another combiner.

Check your alternator amp rating. This combiner is good to 100 amps. They have bigger combiners if you need them.
Click to expand...

I didn't see anywhere in the instructions a reference to OFF. If you want to kill current to the boat such as when it is not in use (slip or trailer) do you still keep the standard ON-OFF switchand wire this after that?
 
Slacker said:
Question... I see in the diagram for all of these you need the control wire. I haven't looked for it in the manual yet, but is this wire east to locate? What is the additonal wire that is on my battery come from? Minus the one I just added for the amp I installed...
Click to expand...

By control wire, I assume you mean the starter wire. The easiest access is at the starter slave solenoid, which, I believe, on most Mercruisers, is located on top of the engine port and aft to the flame arrestor.

On my setup the additional + wires were for the bilge pump and radio memory.
 
Slacker, do you mean the remote turn on wire for the amp and stereo?


unlvrebel,

I kept the battery disconnect switch (I assume that is what you mean) and wired everything before that.

The stereo battery has it's own circuit breaker, that can act as a disconnect. It is also after the combiner.

It is so easy to wire this thing up it doesn't seem right. Plus there is no switching and I can maintain a charge on both batteries at the same time with a shore trickle charger.
 
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