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Perko Switch Setting for Dual Battery Operation

I Roll

I Roll

Well-known member
I need some opinions (which I'm pretty sure I can receive here ':D'). I have a two batteries and have heard conflicting information about the best way to operate. Some folks say it's better to run with the Perko switch in the "All" position, others say either on battery 1 or battery 2. I was even told that running in the all position could burn up an alternator. Now I just run on battery 1 when I'm headed out for a ride, and battery 2 when I'm headed in. Any thoughts? Also, would alternator output (amp's) matter?
 
You can indeed run on both if they are both at the same charge level. A problem though when one is drained and the other is charged. They will try to equalize and could start a fire if theres a weak point in the wiring. Theres no real reason to run both. If you need both to run extra lights etc. get a bigger battery, and alternator.

I still dont know why they have a both position on them. I guess if both are too low to crank an engine, putting it in both might give the benefit of a one time boost enough to crank it up.

The alternator will only charge up to a certain rate. not likely you will damage it unless its looking at a short.

I think I would keep one unused for backup in case you did kill the primary one.

Scotty
 
Thanks for the reply Whitebear. That also got me thinking. My batteries are almost 5 years old. They both seem to be fine but I was thinking about replacing one for now and then the other when it actually died. That way I know that I should have at least one strong battery. Based upon your response, if I did that and then ran both I could potentially have a problem.
 
Long as either one will crank the engine fine I wouldnt make any changes. Just check the specific gravity on both and get it where it belongs and keep on truckin. I think I might do as you have been or run every other trip on the opposite battery.

Do you keep a trickel charger on them when your not using the boat. That would be worth considering. You can get little pastic tags called "Battery Mate" that will tell ya how much of a charge each battery has on it. Just glue it right to the top of the battery. Great little easy visual for quick reference.

Scotty
 
I roll The perco switch is one of the things that I would not be without..
What you are doing running one bat. on the way out and the other one on the way back in is the best thing you can do.. Because this way you are keeping both batteries used and charged.... The reason for two batteries is that if we are ware nothing else can get to us and a battery goes down Then we can go to the other battery to get started --- but all to often we forget to switch from 1 to 2 when running and after a while the second bat. will go down.. Now if your having a problem and then find out that the other bat. is low too THEN WE SWITCH TO BOTH so between the two hopefully we get the boat started---Once you get going switch back to just one of the bat. it will charge up much faster than two will at the same time --- plus I agree that running both puts a strain on the wiring and could cause problems.
 
Whitebear covered it, No two batteries are alike even if bought at the same time so there is the potential of boiling one battery in the both position, even more so with a new battery and an old one! 8)
 
from above----"Now if your having a problem and then find out that the other bat. is low too THEN WE SWITCH TO BOTH so between the two hopefully we get the boat started---Once you get going switch back to just one of the bat. it will charge up much faster than two will at the same time "

The instructions with my perco switch indicate there are 2 types of swithces... one allows you to switch while running, the other comes with a warning that switching will damage the alternator ( I think the one that allows you to switch while running has diodes or other electronics to prevent damage)
 
BigFeather

Qatar is GMT +3. U.S. East Coast is GMT -5.

That means I am 8 hours ahead of Florida. When its Noon there its 8 PM the same day here. When its 8P.M. there its 4 A.M. the next day here.

Scotty
 
I don't know about the one switch that says not to switch while running But I do know If you turn the battery switch off when the motor is running you will more than likely ruin your Alternator..Been their done that--
 
Thanks to all you guys for you insight on the proper use of the perko switch. The boat I bought has one, and I've been running it in the "both" position at all times. I'm going to call Perko tomorrow to see what they recommend.

I've found the website for perko inc. Here's the link to the part of the catalog which lists the available switches. However, there was no definitive statement about how to run normal in a dual battery configuration, though it does seem to infer that you only use the all position for emergency starting.

http://www.perko.com/Perko%20Catalog/105-120/lfbbs.pdf

Maybe I'll call perko tomorrow and see if I can get further detail. This topic has certainly sparked my interest.
 
From everything else that I've been able to find, Ron is right about never changing the switch to the off position while running. Not even for a second. It will cook your alternator.

I did take a look at the Perko website the other day. The instructions page isn't available yet (Under Construction). I also took a look at the product catalog to see if they might have additional information there. No such luck (but I did like the locking switch).
 
Sometimes a alternator voltage reg will freak out and there is no battery to send juice to, that means that when you hit 4500 rpm you have about 130 volts dc going to your radios, ignition, Lights, Poof! 8)
 
I have run dual batter switches since 1968. I have run 1, 2 or both at random. On the car engine boats, going out on battery1 and in on battery2. Because you can not hand prop a car motor boat or at least I don't know how. When the switch is in the off position the alternator should not produce voltage or current because, the field is not energized. If they do it is because of residual magnetism, and my boat does this. Also the weakest battery gets the hardest charge because it has the lowest resistance. Loose connectios. corrision and bad cables cause most of the problems--these conditions can exists in the switch.Has anyone figured out how to lub the detent ball in a Perko switch? Thanks folks--Have good weekend.
 
When the switch is in the off position the alternator should not produce voltage or current because, the field is not energized. If they do it is because of residual magnetism,
Click to expand...

It would depend on what you have and how it is wired. Once a Delco is energised it will keep producing even with all the wires removed.
 
Those perkos are nice with dual batteries on Lycomings during cold mornings. Compression with stiff oil can make that bugger a tad harder to start, especially if the batteries are low cranking amps or just getting alittle old. On both, typically she will swing the prop.

I had heard that charging on both could cause problems, but it is what I always did. In the end, just went to a larger cranking amp battery and left the second off to save weight.
 
Your alternator is driven by the belt on the motor once you reach usually 1000 RPMs it is producing voltage --- If the switch is off and this voltage can not go some ware to be used the alternator overloads ---- (not good)
Now it may be possible ??? if the alternator is wired to the motor so that the electronics on the motor will use some of the voltage then you ???may not hurt the alternator???? But if it is wired correctly the power from the alternator goes to the perko switch and then to everything else on the boat.
 
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