BradV
Well-known member
I have seen it a few times on here. But how many batteries do I need to run? what information and power numbers do I need? Right now I am running 3 27 Series batteries.
grouperjim":2iy05c1o said:I frequently overnight 120 mi offshore, so the battery issue becomes very important to me. All my batts remain isolated from each other but charge simultaneously by utilizing the unused auxillary charging lead/plug that comes off the alternator and hangs capped in front of the engine near the bottom of the pan.
Although I carry a third (fully charged) battery, I only use the two which are currently AGM group 31s (same dimensions as the 27s). I like to keep them isolated from each other so what I do is leave the Perko batt switch in position 1. I never select "both" unless an emergency. Battery 2 is hooked up to the aux charging lead.
So the way this plays out while underway is, number 1 batt gets charged at all times via the battery cable. Number 2 battery gets charged at all times via the aux charging wire. Never a need to remember to change the Perko switch unless there is an emergency. All batteries remain isolated. Number 3 battery doesn't get hooked up unless running some underwater lights, and in that case they are alligator clipped directly to the batt.
There are many ways to do it. On a Yamaha 4s just remember that there is an unused aux charging lead that will charge a battery any time the engine is running.
Here is a pic of the charging wire form Yamaha. You can make your own. Retail is about $80. The plug snaps into the aux charging lead (remove protective plug) then exits with the rest of the engine wires thru big plastic chase into the transom, then simply attach the red ring terminal to the positive side of the batt.....done.
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