View Full Version : Please help with second battery install

08-11-2007, 03:43 AM
I have a 2005 outback that I'm adding a second battery to. I'm doing this because I just added a 700 watt kicker 5 channel to my 600 watt four channel to handle my 6 polk db651 boat speakers, two Samson tower speakers, and 10" sub. I'm worried that I will run my stock battery dead when just floating and listening to music. I bought a bigger second battery and a Perko switch. My question is how do I hook up the boat's big red power wire to the Perko switch? It's a standard cable with a post clamp on it...but the perko switch requires a smaller cable hole.

Hopefully this makes sense to someone and they can help me. I understand that a cable needs to go from each batteries positive terminals to the switch and a cable joining both negative posts. I'm just stumped on the boats power cable to the switch.

08-12-2007, 12:10 AM
A few different ways this can be done. This is what I did:
http://thumb16.webshots.net/t/42/42/8/99/31/2750899310079687796FooTtM_th.jpg (http://sports.webshots.com/photo/2750899310079687796FooTtM) http://thumb16.webshots.net/t/38/38/5/14/82/2357514820079687796aduGWx_th.jpg (http://sports.webshots.com/photo/2357514820079687796aduGWx)
The boat negative to one battery, then jumper to the other's neg. The 2 positive leads to 1 and 2 of the perko. From there to a stinger distribution block and then to amp (fused), to dash accessories, and to the starter (bottom). It was tight but I managed to get the starter cable in there. The accessories, amp, and head unit negatives directly to the batteries. Battery terminals, wires, distribution block, etc from darvex.com (excellent prices).
My system is pretty simple, one 550 watt amp for the tower speakers. My 2nd battery is the same as the first. Both have the same charge/discharge characteristics and have been well taken care of by my alternator so far. Most folks will use a deep cycle battery for #2 and hook it up to the stereo. I've had my stereo on for 3-4 hours, stock battery handles it fine. For something more complex, you may need the deep cycle battery. Hope this helps.

08-13-2007, 06:59 PM
I just did this job myself a couple of weeks ago. What I did....Bought Perko switch, (2) 18 inch red battery cables, (1) 12 inch black negative cable (both cables were size 2 wire), battery and battery box. I cut the existing automotive type battery terminal off and crimped on a regular round eye connector that would fit on the common post of the Perko. This was the hardest part, as I was lucky to be able to borrow a crimper tool from a friend. That's big 2/0 cable and you'll want a good crimp.

Wiring is as noted in the post above. Boats existing positve to the common post on the Perko. One positive from each battery to the respective post on the Perko. Just run the one negative cable from the new battery to the negative of the existing battery.

Bought all cables and connectors at West Marine.

Hope it helps.

06-24-2008, 07:01 PM
I am in the process of installing a second battery in my boat for my planned electronics. I asked the dealer for a quote to do this job and they came back with $700. Sounded very high to me, so I asked what was included:

They said: new battery cable ($85), dual battery cable ($41), voltage relay ($152), tyvek tags ($8), battery box ($11), battery tray ($7), battery ($80), and labor ($180).

They said they would have to pull a new battery cable from the engine?

Does this sound right or does it seem like a bit of overkill? Do I need a voltage relay and do I need to install a new battery cable from the engine?

I welcome your thoughts, thanks.

06-24-2008, 08:03 PM
Well the answer to the new cable question is yes and no. Yes... you do if you don't want to drive all over looking for a copper ring end that fits a 2/0 cable. Then have to find and drive the boat to a person with a crimpper like I will. No... if you have an idea were you can find this stuff. I went to a welding supply house and spent 2 dollars for my end ring and saved a bunch of labor by not taking the floor up and then having a extra cable that I would never again have a use for.

You don't need the tyvek stickers. Battery box is cheap and its to small, you should get a deep cycle battery for the second batt and they don't fit in the factory box, I learned that the hard way. Box for sale if needed.

If you want to do this thrifty then I would go to BEPmarine.com and get the VSR unit somewhere online. The cables from a supply house near you, 2 red ones,1 black, The instructions are on BEP's website and you can call if your not clear on something/anything.

I will snap a picture when I get a chance because its straight forward when in sight.
I have the cables that the factory use now, however I am going to get some that are a little longer as to improve the cubby area. So if some on needs the two oem red ones let me know.

06-25-2008, 02:23 PM
I did this on my own and it wasn't bad. I found the wires and the terminal at an automotive supply. I went to a mom and pop hardware store and they let me borrow their huge crimper to put the terminal end on the wire. I bought my own battery and box...plus I installed a battery on/off switch for both batteries...works great. If you look around enough...you can find them.