So what exactly does a Perko switch do?

Ok, so I'm probably the only one who doesn't completely understand the Perko switch. When I bought my boat, it had two batteries and a Perko switch. The starter battery is hooked only to the starter (#2 on the Perko dial). The deep cycle is up front and has everything else hooked to it (#1 on the Perko dial). I can crank the battery with the Perko set to one, two or both, but not off. I can run the stereo (accessories) with the Perko set the same way.

Is this correct and what is the best way to use the switch for optimal use of both batteries? I assumed I would crank and run the boat with the Perko set to 2 (starter). If I decided to turn off the motor, chill and listen to some tunes, I would set the Perko to 1 (deep cycle) to keep the starting battery from draining. Am I on the right track? When would you ever run "both" on the Perko?

I also have mounted an onboard charger that I have hooked directly to both batteries that I keep plugged in while the boat is not in use.

You run a cable from the positive side of the battery you want to start the motor with, to the terminal marked #1 on the back of the Perko switch.

You run a cable from the positive side of your second battery (stereo battery) to the terminal marked #2 on the back of the Perko switch.

On the common you run the main cable from the engine and connect it to the common terminal on the back of the Perko switch.

When the boat is not on the water keep the switch in the off position, when you arrive at the ramp I flip it to position #1, start the motor and you can use anything want on the boat. While motoring around the alternator is charging this battery, #2 is being left alone. When you want to play the stereo with the engine turned off then flip to #2, all power is being pulled from the #2 battery, #1 is not being used so I have a fully charged battery waiting.

The combine function will make the two batteries act as one. This is how you could kill both batteries and be SOL. You can also have the switch on combine when motoring around which will charge both batteries but it is also a big strain on the alternator.

When charging the batteries with the charger, put the perko at the off position and charge each battery.

Murphy, that's pretty much how I use it. If the battery charger is wired directly to each battery, does it matter if the Perko is set to "off" for both batteries to charge? I try to do that but sometimes I forget and leave the Perko set to the starting battery (#2 in my case). Am I only charging the starting battery in this case?

Duh! It turns the Perko on and off doesn't it? If you leave the perko in the"both" position you essentially create one large battery and the battery charger will have a current path to each. It will take much longer to charge a "larger" battery. If the switch is in the "off" position they will be isolated and charge seperatly. I guess it would kinda depend on which type/brand of onboard charger you are using also.

Originally Posted by murphy_smith

You run a cable from the positive side of the battery you want to start the motor with, to the terminal marked #1 on the back of the Perko switch.

You run a cable from the positive side of your second battery (stereo battery) to the terminal marked #2 on the back of the Perko switch.

On the common you run the main cable from the engine and connect it to the common terminal on the back of the Perko switch.

When the boat is not on the water keep the switch in the off position, when you arrive at the ramp I flip it to position #1, start the motor and you can use anything want on the boat. While motoring around the alternator is charging this battery, #2 is being left alone. When you want to play the stereo with the engine turned off then flip to #2, all power is being pulled from the #2 battery, #1 is not being used so I have a fully charged battery waiting.

The combine function will make the two batteries act as one. This is how you could kill both batteries and be SOL. You can also have the switch on combine when motoring around which will charge both batteries but it is also a big strain on the alternator.

When charging the batteries with the charger, put the perko at the off position and charge each battery.

sounds like the best way to be doing it.

How is running the boat when using the combine function on the perko a drain on the alternator? I understand how charging a battery works, and why it would take longer to charge both at the same time. I just dont see how it would harm the alternator, it will produce what its going to produce regardless of whats connected to it right? If not I'd love to know why! I have a pretty good understanding of basic electrical (taken an electrical engineering class).

Well I have a two bank charger. And if I wired each battery directly to a separate bank, it seems that it will charge both or either battery as needed regardless or where the Perko is set. Am I missing something here?

Nope. I think you have it right.

A dual bank charger runs separate profiles for each battery or bank. This is required because the two batteries are put up with different levels of charge, used very differently, age differently and have different impedances (path of AC resistance). Isolated charging keeps you from over and undercharging which extends your battery lifespan. If the Perko switch is set to ALL or BOTH while AC charging then you have circumvented the intended isolation.

David
Earmark Marine

David, thanks. Maybe that explains why I had dead batteries the last time I went out. I tried to start it and no good. I then went to the Perko and someone had set it to "both" (I rarely, if ever use "both"). So I switched it to the starting battery and nothing. Switched it to the deep cycle and nothing. Both batteries appeared drained. So even if I had the battery charger plugged up it wouldn't have or didn't keep the batteries charged since it was set to both?

Will my 2 bank charger work correctly if the Perko is set to either 1 or 2?

Good info. That is what I'm looking for thanks.

Joey - the more batteries you are trying to charge with an alternator, the more strain on the alternator thus making it work harder and shortening it's life span.

Most of our inboards alternators can handle a dual battery setup. I have a four battery setup and I would never flip my switch so that it would charge the 3 stereo batteries in fear of burning up my alternator. That is why it is very important to have an on shore charger to bring the batteries back to full capacity.

Wake,
Provided that everything else is wired in accordance with how a dual battery switch is intended to be used then you would always keep the switch in the "OFF" position for total isolation during AC charging or whenever the boat is in storage. If you had a functional AC charger on batteries that were initially charged then I suspect you have another issue to deal with. While an incorrectly set switch would keep the AC charger from operating optimumly it would not be the cause of dead batteries.
For now I would charge each battery individually all the way full, remove the charger with the switch in the "OFF" position and see if the charge can hold at 99 percent for several days. If it drops more than a small fraction of a volt over that time then I would take them in and get them load tested. Fluid levels okay? Nothing hooked directly to the batteries other than the Perko switch connecting cables?
If your batteries were really dead (below 10 volts for example) beforehand then your charger may trip into protection and do nothing. An empty battery looks like a dead short to a charger. Before the new season begins it is a really good time to do a thorough check of things so that you can have confidence in your system all season long.

David
Earmark Marine

Wakemania, you seem to be asking the correct questions so you can better understand how the switch works with your charging/starting system. Since you have 2 different types of batteries you should have run everything related to your stereo directly to your deep cycle(battery #2). The only downfall to this is that you can't completely disconnect the deep cycle battery from the stereo without pulling a terminal off the battery. With it hooked up like this you will have your main battery positive from the starter go to the common terminal on the perko, the positive of the starting battery will go to the battery 1 terminal on the perko and the positive of the deep cycle battery will go to ther battery 2 terminal on the perko. As for grounds you will have the main ground coming from the engine block going directly to the starting battery negative terminal. Then a jumper from the negative terminal of the starting battery to the negative of the deep cycle battery. Since you have the batteries in 2 different locations you may have both batteries negatives hooked directly to the engine block.

It is important to know how manipulate the switch to achieve the correct results. With the boat running think of the switch as directing the power/electricity to the batteries and when the boat is off think of it as being a battery disconnect switch. Since you have the stereo connected straight to battery 2/deep cycle then the stereo is always going to be able to play assuming your battery isn't dead no matter what position you have the switch in. Here is how I would use it. Whether you are leaving the boat in the water or on the trailer leave the switch in the "off" position. Keep in mind that if you leave you boat in the water you want to connect the bilge pump(s) directly to one of the batteries so you don't go away for a few days and you boat sinks because the bilge pumps aren't powered. When you get to your boat move the switch to position "1" and turn on your blower as that will not work with the switch in position "off". Then start your boat. This means your boat is starting just off the "starting battery". Once started give the throttle a little bump up to 1000-1200 rpm's while in neutral. The reason for this is that you may have a self excited alternator and it might not turn on until you get up over an idle. If you leave it at an idle and notice that your voltmeter doesn't read above 12.5 or so you have a pretty good idea your alternator is not turned on. Then after warming up go ahead and move the switch to the "both" position. This means you are charging both batteries at the same time. Now if you want to sit and listen to the stereo with the boat off move the perko switch to position "1". This isolates your 2 batteries leaving your starting battery fully charged for when you start. When you want to start your boat leave it in position 1 and start. After it has run for a bit switch the position back to "both". Keep in mind that if you really kill your deep cycle battery and run for a long period of time you are going to work your alternator very hard and have a chance of burning it up.

Oh yeah, make sure your switch is a "make before break" type switch otherwise you will never want to change positions while the boat is running. Now if you are willing to spend a few more dollars getting a battery combiner/seperator does most of that switching back and forth automatically so you don't have to screw with a switch. Remember, you bought your boat to enjoy it, not to worry about screwing with a switch constantly. Something I think everybody should have if they are running amps is a dual bank charger as well. This is the only way to really make sure you batteries are fully charged after every use and will increase the life of the batteries and every other piece of electrical equipment on your boat. Like David said if you use a dual bank charger you want the batteries to be isolated when charging to maintain your batteries the best. When using the charger turn the perko to off, 1 or 2. You can put it in any position except both.

Brett, thanks. That's a lot of information to digest, but I'm working on it.

I normally leave the Perko switched to the starting battery and never move it. If my 2 bank battery charger will work correctly with the Perko in any position but "both", shouldn't I be fine there? Then if I shut off and listen to the tunes, I can switch the Perko to the deep cycle while leaving my starting battery charged. Then move it to the starting battery to start and either leave it there or move to "both" once cranked.

The reason I always have in the past left the Perko set to the starting battery was because I have the 2 bank charger and always plug it in when the boat is not being used. I can see switching the Perko to "both" if I felt I had a pretty good drain on the deep cycle and needed to charge it a little with the alternator while running before putting the boat up. By the way, could you at some point while running switch the Perko to the deep cycle and just charge it if I felt the starting battery was fully charged? I know I can switch the Perko while running as I have done so.

Thanks

Originally Posted by wakemania

Brett, thanks. That's a lot of information to digest, but I'm working on it.

I normally leave the Perko switched to the starting battery and never move it. If my 2 bank battery charger will work correctly with the Perko in any position but "both", shouldn't I be fine there? Then if I shut off and listen to the tunes, I can switch the Perko to the deep cycle while leaving my starting battery charged. Then move it to the starting battery to start and either leave it there or move to "both" once cranked.

The reason I always have in the past left the Perko set to the starting battery was because I have the 2 bank charger and always plug it in when the boat is not being used. I can see switching the Perko to "both" if I felt I had a pretty good drain on the deep cycle and needed to charge it a little with the alternator while running before putting the boat up. By the way, could you at some point while running switch the Perko to the deep cycle and just charge it if I felt the starting battery was fully charged? I know I can switch the Perko while running as I have done so.

Thanks

If you have your stereo hooked directly to the deep cycle battery you don't even have to move the switch from "1" to "2". Leave it in "1" the whole time. The way you are using the batteries you are basically using them as 2 completely stand alone banks since you charge your starting battery with the alternator and the deep cycle with pretty much only the charger. This isn't bad as long as you are getting the play time you want out of the deep cycle battery. You may want to think about getting a low voltage disconnect so you don't discharge your deep cycle battery too much though. Your alternator is probably not getting worked hardly at all. Yes, you can switch to both to charge both batteries at the same time while running or you can move it to battery 2 just to charge the deep cycle battery although if it is too discharged the ECM may shut down because of low voltage. Just don't drive around for an hour after you just completely discharged your deep cycle battery or you will kill the alternator.

Brett, that's pretty much what I was thinking by reading back through this thread. I originally got the 2 bank charger to charge the deep cycle but to also keep the starting battery topped off due to long layovers and/or cold weather. I figure it will increase the battery's life span. I see what your saying about draining the deep cycle too much, so I'll keep that in mind. Does the low voltage disconnect shut the battery down when the voltage drops to a certain point? How would I go about installing that?

Originally Posted by wakemania

Brett, that's pretty much what I was thinking by reading back through this thread. I originally got the 2 bank charger to charge the deep cycle but to also keep the starting battery topped off due to long layovers and/or cold weather. I figure it will increase the battery's life span. I see what your saying about draining the deep cycle too much, so I'll keep that in mind. Does the low voltage disconnect shut the battery down when the voltage drops to a certain point? How would I go about installing that?

It would be wired inbetween the battery and the amp distribution block. It would break the connection once it senses the battery was discharged to whatever setpoint it is set at.

All the above stuff is valid, it is nice knowing you have a second battery. But the best part is sitting by th eswitch, and turning it to off when we are chilling. Then asking a friend to fire it up and head for blank. It wont fire. its funny to me every time.

I need to be de-confused! My Sanger V210 - 05 is set up like Brett described above. The #2 battery has a 0 gauge 200 amp fused wire to the positive side in addition to the perko's positive wire from the #2 slot. The negative side of the #2 battery has the "jumper" from the #1 battery and the grounding wire (also a 0 gauge). This may also be grounding the dash controls too (I am not sure since I bought the boat used and it was set up already).

The stereo, navigation lights, tower lights and amps all work whether the switch is on #1, 2, All or Off. Shouldn't they all stop working on Off? What am I missing?