View Full Version : Dual Battery Perko Setup

02-19-2011, 08:32 PM
This a great forum and have been reading the past couple weeks.

Ok fellas Just bought an 09 LSV and looked thru all the dual batter/perko threads and couldnt find an answer to my question. Currently have a single battery and going to upgrade to a dual battery with a perko switch.

My question, do i need to buy 2 fresh batteries? Or the 2yr battery will be fine and buy the new battery for backup? I saw the thread talking about if youre running a new battery in parallel with an older battery the risk of shortening the battery life of both.

Anybody pickup a new battery and put the perko on, or went and bought 2 new batteries (expensive)


11 Outback V
02-19-2011, 08:57 PM
For the longest life of the batteries I would suggest getting two new batteries, that will give you the best results in the long run.

02-19-2011, 09:33 PM
The starting battery and stereo battery are used very differently so identical batteries will age very differently. Its critical that two paralleled stereo batteries are identical and replaced simultaneously. Its not so critical that the starting and stereo batteries are the same size or age but its not a bad idea for both to be the same type whether flooded or AGM. If my starting battery rests at much less than 12.5 volts after a good charge then I would replace it while upgrading the stereo battery. A dramatic difference in the ability to accept a charge is troublesome.
An old an aged battery is particularly hard on your alternator so there is a time that its more cost effective to replace it even though its getting by.
Some boaters will use two large deep cycles, one for the stereo and one for starting. With a small block in warm weather its not an issue to sacrifice a few cranking amps in favor of the extra amp/hours. This gives you the ability to rotate the battery usage every weekend which extends the life of both batteries. Easily done with a manual battery switch.

Earmark Marine

02-20-2011, 12:50 AM
Clam- doesn't gave to be expensive. Stop by Costco or walmart and buy a rv/marine battery. Should set you back 75 bucks and the perk another 45 or so.

I am often amazed how much people spend on accessory items like stereo and lights etc but skip the battery upgrade. Definitely a worthy investment.

Exile audio

02-20-2011, 01:14 AM
fellas thanks for resonding back to my post. this is the first boat i've owned and i'm a 'newb'. so i've been doing plenty of research on the moomba forum.

after searching the forum i couldnt find any posts of folks buying batteries in pairs (when adding a second audio battery) or just simply buying an additional deep cycle battery (audio) to pair with the 'stock' battery.
and i'm thinking of going the bluesea or similar route. i can see myself or wife getting that perko switch in the wrong position and being stranded somewhere.



02-20-2011, 02:55 AM
You really have to decide what you are doing with your second battery before you jump to conclusions. I just added a second battery. I added a Perko switch. I have no intention of using my second battery for anything other than a backup start battery. I'll keep it charged. We usually park the boat to hang out and run the stereo from 20-60 min. before we power up and run again. You have to develop your typical profile and decide your battery setup based on the same info. Mine was easy. Don't be a fool either way.

02-20-2011, 01:24 PM
I got a question for you guys. Lets say your sitting running your stereo for a while and your perko switch is set on #2, do you try and start the engine on battery #2 when your ready to go to see if it has enough juice or do you switch it straight to #1 to start it?

02-20-2011, 02:14 PM
I switch it back to 1 and start it, then i switch to BOTH to charge all my batteries at the same time.

I don't try to start on my stereo batteries in-case they are that low..Ive never had a no crank on my boat though, but i have forgot to charge my stereo batteries and lost tunes for a new few minutes.

02-20-2011, 02:50 PM
After a period at rest you may switch over to the starting battery or 'ALL' before starting. However, if you go from the starting battery to 'ALL' after the boat is running, its very important that you don't pass through 'OFF' once the boat is running. Its potentially damaging to your alternator if you are using a basic switch.
If considering an ACR/VSR (automatic device) do a little research before your selection. Our favorite set-up is a SurePower voltage sensing solenoid used in combination with a Blue Sea dual circuit battery switch. We also use a different wiring schematic. This package better addresses every scenerio and closes any loopholes found in other products.

Earmark Marine