Perko diagram question

RyanDundee

Recruit
Joined
Feb 21, 2017
Messages
2
Hi I just picked up a boat and want to understand my wiring. Although it's kinda cobbled up I think I can explain it. The perko has lead 1 going to battery 1 positive, lead 2 going to battery 2 positive. Battery 1 ground goes to the engine and then connects to battery 2 negative. Now my question is the perko common goes to the starter. Is that how the alternator is getting voltage back to charge the batteries? Not much of a mechanic here so I just want to understand.
Also, I have 7 different wires connecting to the positive and negatives of the batteries. I assume for radio... ignition... etc. I plan on tracing all these down but is it safe to say if I connect them to a fuse panel and to battery 1 that if I have the switch set in 1 it cannot use power from battery 2 and I can save that for srltarting the engine if I am sitting running the battery for an extended period of time?

Thanks a bunch!!!!
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,582
Hi I just picked up a boat and want to understand my wiring. Although it's kinda cobbled up I think I can explain it. The perko has lead 1 going to battery 1 positive, lead 2 going to battery 2 positive. Battery 1 ground goes to the engine and then connects to battery 2 negative. Now my question is the perko common goes to the starter. Is that how the alternator is getting voltage back to charge the batteries? Not much of a mechanic here so I just want to understand.

Yes this is how the battery is charged while the motor is running. It changes which ever it is switched ON, or BOTH.

That said, I'm assuming there is nothing else on the boat such as an isolator or Automatic Charging Relay (ACR)

Also, I have 7 different wires connecting to the positive and negatives of the batteries. I assume for radio... ignition... etc. I plan on tracing all these down but is it safe to say if I connect them to a fuse panel and to battery 1 that if I have the switch set in 1 it cannot use power from battery 2 and I can save that for srltarting the engine if I am sitting running the battery for an extended period of time?

Thanks a bunch!!!!

That is also correct
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Common is the feed to the engine as well as the charging for either or both batteries depending on what position the switch is in. There are as many ways to connect accessories as there are people on the planet but the basic theory is to connect all accessory loads (the +12 volt feeds), except for the bilge pump, to the COM terminal as well. You therefore have ultimate control of the system. You can charge either or both batteries, power accessories from either or both batteries, or start the engine from either or both batteries. But -- some folks like to wire accessories to the battery they designate as the house battery and leave the other one for starting only. But that's why you have the switch. Your the traffic cop for the electrical system. Use the switch as you feel necessary. Just don't set it to OFF with the engine running.
 

RyanDundee

Recruit
Joined
Feb 21, 2017
Messages
2
Awesome!! Thank you very much!!!! I don't think there is a isolator or ACR. But I guess I don't know what one would look like lol
 

Grub54891

Vice Admiral
Joined
Jun 17, 2012
Messages
5,908
It would be smart to remove the extra wires from the battery, and run a separate fuse panel or buss for them. That will make a cleaner looking set up, less corroded wires, and easier hook ups when changing batteries. Also, ABYC standards only allow 4 wires to any one terminal, I prefer only the battery cables at the battery, and one jumper if necessary for the fuse panel or buss bar.
 
Top