Connect 2 batteries

[Beckoning]

I have a 2-battery system with a PERKO switch. Using very heavy gauge battery cables, it is difficult to jam everything inside the little PERKO. How to connect 2 positive (RED) battery cables that will go to the same PERKO bolt connector so I'm just putting one cable onto the PERKO instead of cramming 3 onto the post? There must be some sort of connectors. Alternatively, I could bolt the 3 eyelets together and wrap the wad in heavy rubber insulation. Is there a danger in connecting 2 red cables to a 4-6" pigtail cable that attaches to the PERKO? Is there a risk of overheating the pigtail when I'm running on both batteries to charge them? BTW, I had a PERKO for 14 years on my prior boat, and it worked like a charm....thinner cables, fewer toys. Lots more amps flowing on this boat......4 electric riggers, Lowrance, Garmin GPS, radio. All powered by a 150hp Tammy.....I'm in heaven.

 

[makomark]

why would you need to put three cables onto one post???

a perko part number for the switch would be a tremendous asset to share - so would the battery cable size..."very heavy gauge" is very subjective.

 

[Beckoning]

My bad. Agree that I misrepresented the situation. The cables are 5 AWG, PERKO model 90108A (1-2-both-off). I think I wired it according to the first diagram below that came with the PERKO: positive from the engine and from the helm to the bottom post; 5 AWG to battery #1, 5 AWG to battery #2. Motor negative to Negative post on battery #2; Helm negative to Negative post on battery #1. My problem is new. Both batteries are fully charged, brand new. When I try to start the engine using battery #2, it starts fine. When I try to start the engine using battery #1, all I get is the dreaded "click-click-click". On my prior boat, I had the same PERKO, and I could start the engine on either battery #1 or #2. My current boat's engine is Yamaha 150hp, with an alternator, I think.

My prior boat's PERKO was wired as shown in the 2nd and 3rd diagram below. The difference is there is a 2 AWG connecting the negative posts on each battery. Then, the negative from the engine is connected to battery #2. If I follow diagram #2 and #3, I have 2 questions: 1) Do I need to do anything special since the Yamaha 150 has an alternator? 2) As in the past, I would start on one battery, switch to "all" when motoring out onto the lake, then switch to the other battery to run electronics and electric riggers. That preserved the starting battery when I was done fishing. Is that correct, or am I imagining things?

Bottom line.....the diagram that came with the PERKO (top diagram) is misleading and maybe either wrong or incomplete. The other two diagrams are accurate

 

[makomark]

Bottom line.....the diagram that came with the PERKO (top diagram) is misleading and maybe either wrong or incomplete. The other two diagrams are accurate

no...its being misinterpreted.

If you are going to swith the Positive cables, then the negative cables need to be connected and at the same potential. run a short cable between the NEG terminals on both batteries...that should resolve the clicks only-no start issue when using battery #1.

as far as operation with the alternator, nothing beyond common sense is required...the biggest foobar you can commit is to move the switch to OFF while the engine is running... most will ensure batteries are both charged before departing...then use one battery (not both) at a time (and alternate batteries between outings). With the alternator, there shouldn't be a huge reduction in baterry capacity unless the engine is off most of the time and the electronics used extensively...then they will run out on either battery and then switch over to the other before heading back in...

The only time the BOTH setting is used is when neither battery has enough charge to start the engine by itself...

 

[Beckoning]

Thanks, all. I followed the yellowish diagram above, and all seems to work fine. Key seems to be connecting the negative posts of the 2 batteries. Now, when PERKO is on "all", both batteries are being charged. I start on #1, turn to "all", run out 2 miles to trolling spot, turn off the 150hp (with the alternator), switch to battery #2 for electronics and run on the 9.9 kicker (no charger). After 2-3 hours of trolling on Lake Michigan (salmon, steelies, lakers), I try to start on #2. If it starts, fine. If the starter labors, I switch to battery #1 to fire up. Switch to "all"to return home. So far, so good. I'm putting up another post for help diagnosing gauges that don't work.