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I purchased my 1985 Montauk 17 with a Perko dual battery switch and two batteries. Whenever I start my boat, I use the "all" selection on the switch to get the engine to turn over. Generally I just leave the switch set on "all" while I'm cruising around. Is there a better way I should be using the switch for charging the batteries, using the accessories, etc?

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Be careful in the "all" position. One dead battery could drain the spare. Should always go in one position or the other and NEVER switch from one battery to the other with a running boat. They have new dual battery switches that allow for both batteries to charge at the same time. With the Perko switch, the only battery charging is the one that is designated by the switch.
Garris

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I do the same, start and run on both batteries. But when at anchor fishing for a long period of time switch to 1 battery to run accessories, like fish finder, radios, gps, lighting at night, saving a fully charged battery for starting. Also, to prevent fires when not using the boat, shut it completely off, to prevent something shorting out. Your bilge pump should be wired directly to the battery so it always gets power even with the switch off. Also don't change the switch with the engine running.

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If you always use one battery then you always have a spare full battery incase you run yours down like sitting with radio on. I always used 2 big deep cycles as they are generally big enough to start most outboards. every other trip I would switch which battery I used.

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Garris,

If I leave the switch set at "all", will both batteries charge while I'm running about?

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Most of today's battery switches are make before break and allow for switching between batteries with the engine running.

If your switch is not a make before break, you can do damage to your charging system, it would be the same as turning the switch to off with the engine running.

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Thanks for the feedback. I've been operating on the "all" switch for several years now, but it seems that is the least optimal position unless I'm in an emergency situation to get enough power.

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No, you are fine doing what you are doing. "All" is used when the engine is running for charging both batteries. If you are at anchor/drifting/electric trolling for long periods of time without running the engine, and you have a relatively high electric load, it is best to isolate the batteries by switching to one or the other. That way you are sure to have a fresh battery for starting in case the battery in use gets drawn too far down.

As mentioned, modern switches are make before break and there is no issue switching between batteries when the engine is running (unless you have a VERY OLD switch.)

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I'm not Garris, but YES!

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The switch also alerts you to issues with your charging system if you only use one battery at a time. For instance I have twins on my boat and each motor has its own batter but it goes to switches so I can choose which battery to use for which motor. Well was doing some work in the bilge and unhooked the batterys and somehow missed putting the charging cable back on the port motor. Went out a few trips and the battery slowly drained then all of a sudden the motor started to bog down. I tried to restart but no power to turn it over. switched to other battery and it started right and up and ran fine. Point of the story is if your charging system fails and your battery dies you are dead in the water if you are on all but if you can switch to the fresh battery to get you home if you only run on one at a time.

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Regarding the emergency situation... it depends.

If one of your batteries has been deeply discharged, you would NOT want to use the "ALL" switch setting. That is because the bad battery will drain power from the good battery until they are equalized. Soyou would not combine them, insyead you would keep them separate and select only the good battery to start the engine. Once they engine has been restarted, you can combine them again and they will both charge.

However, if both batteries have been equally deeply discharged, and you are trying to re-start the engine on a prayer, then yes, combining them with the "ALL" switch will give you the best chance of having enough amps to turn the starter and restart the engine.

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JRP, thank you. I have a much better understanding of how to operate my batteries. I generally have issues with my batteries being drained and from what I gather, batteries will charge together on the "all" feature, but charge more optimally if isolated on the switch. Hoopefully I won't have to charge my batteries as much with an AC charger.

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For best performance from your batteries you should always top them off after every trip unless you do not run any accessories, and unless you are running your outboard (and it has a good output) for hours, your batteries will not be fully charged.

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Since you have 2 batteries, you might consider installing an Automatic Charging Relay (ACR). An example I'm currently installing on my 1985 Outrage 18 is:

https://www.bluesea.com/products/7601...24V_DC_65A

This device helps maintain safe charging of two batteries, combining when appropriate and isolating when one or more is in an over/under voltage state. It also can isolate your house battery and associated electronics during starting. A status light lets you know when it is isolated (typically due to one battery being discharged), so you get a heads up and don't combine to start. There are other more sophisticated models that prioritize charge to one of the batteries.

I'm using this in conjunction with:

https://www.bluesea.com/products/6011...ch_-_Black

which normally has the house and start batteries isolated, but with a provision for combining if need arises.

Dennis

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Dennis,

So that device would only come into play when I switched my batteries to "all"? I'm assuming that if I manually isolate the batteries on the switch than that device doesn't function.

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Sorry to join this thread late but since you are doing serious work on the boat's electrical system, I have to ask.....

Why do you need 2 batteries to begin with. Almost all classic and post classic Montauk owners run with one battery. Unless you have serious lighting, electronics or a trolling motor, I don't see the benefit.

I did complete electrical re-wires on both my classic Montauk and Outrage 17.

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Phil,

The boat was set up with a two-battery system when I purchased it. I was just wondering how it can be used most efficiently.

I've seen your re-wire projects, I wish the interior of my center console looked like that.

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No, an ACR is a parallel system that is always monitoring the charging source and both batteries. You can find an installation diagram on the web page linked previously.

However, as PhilT mentions, many people run their Montauks and other boats with just a single battery unless there is a load that demand two. Mine came with two and a battery switch, and when I redid the electrical system I went to a single battery with no switch. I used a switchable breaker for the house circuits to disable loads when the boat is not being used. Simpler is often a more reliable solution.

With my Outrage, I'm adding an electric davit for prawning, as well as an electric trolling motor. Hence the 2nd battery and associated switch and ACR.

Dennis

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I am not Tmann45 but I will chime in (could not resist tmann). If you continually run and operate in the "all" position....you defeat the reasoning for two batteries in the first place. You are basically running with one big battery. The charging of both batteries from an outboards system while both are in continual use would be a trickle at best (and as stated earlier the weaker of the two batteries would steal charge from the good one) and you would be better off charging one without diverting the amps. To me the need for two batteries is like having a spare tire. One needs to be charged and in good shape for emergencies. Like Phil says, (and my opinion of the way you are using them) you may as well go for a single battery.

However, Dennis brought up a very modern and well thought out design for two batteries. I have the same system on my boat. My secondary (non starting) battery always gets the charge from the motor but the only function/draw I put on the battery is for the electronics (negligible). It is separated from the other battery. With the ACR relay.....you also protect electronics. Do study the Blue Sea system. Your wiring is already there and with some modification you would have a superior system with the charged (spare tire) available.

Garris

Dennis,

In addition to combining the charging the ACR Relay disengages the secondary battery when starting the motor. The relay is connected the the starting position of the key (not the "on" position). As you flick the start, some internal connection gets interrupted. Davits, anchor winches, wash down pumps, etc (the high amp surging starter motors).... should be on the starting battery if you are separating the electronics. All my electronics are isolated.

Editing

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Garris, the Blue Sea ACR calls that Start Isolation and it removes the connection between the two batteries (opens the relay). Depending on the loads you have and your battery bank capacity, it might not be necessary on all setups. I did not need that capability and did not wire mine up to the ignition switch.

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Tmann45, thanks for the nomenclature/definition....always a pleasure to read your posts. I am going with Raymarine downvision, auto pilot, radar......anything I can do to help protect the big $$ stuff from surge I do. It is just a nice extra with the design. With or without that starting feature, the Blue Sea system is really a great step up from the Perko.
Garris

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So with a mid-grade fish finder, a CB radio and a bow light to power, it sounds like I don't need the Blue Sea system.

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The protection of electronics is an additional feature. The system itself monitors and isolates each battery for charging based on need. Similar to you running in the "all" position with your current set up but a bad battery would not be draining the good battery. You can also isolate your functions accordingly. You can run the functions of your boat off of one battery with a fully charged battery available to "jump start" your boat by turning the switch for a moment to "combine", then back to the original positioning. You could protect your GPS, fish finder, CB, VHF, etc... incidental of how much they cost you. Lights and other accessories are not bothered by the spike/transient that shoots through your system when starting.
Garris

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Thanks Garris. Aside from protecting your electronics, does the system do a good job directing the power to the battery that needs charging? Do you find that you still need to recharge your batteries back on shore?

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Depends on use of boat, sitting time, bilges auto on, down rigger use, charging system of motor, etc.... Not a simple answer. However, the Blue Sea system is the most efficient "bang for the buck" out there. There may be other manufacturers of the same engineering but I never tried to research because I am pleased with the Blue Sea product. When my boat was in its slip, once a month I would take my charger down there with auto shut off. I thought the charger was broken the first time because my secondary battery shut off the charger in the first 30 minutes. In fact, one of my mentors actually designed and was making this system in his shop in Petaluma years ago and gave the technology to Blue Sea (Blue Sea refined), a Mr. Fred Fritz.

Garris

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Sorry but not Garris again :-).
The charge is not directed to the battery that needs it per say. What ever battery is connected to the charger is the one that gets the charge until it meet certain specs (do some reading of the links on this site: https://www.bluesea.com/products/7610...4V_DC_120A.
When that battery satisfies those conditions the batteries are connected, just like putting your battery switch on 1+2 or both. Then both batteries are being charged as long as the relay keeps them combined, other conditions might come into play and change what happens. The ACR is nothing but a battery switch that connects the batteries together.

Usual two battery system goes like this, one starting battery and one house (lights, electronics, accessories, etc.) battery. If your starting battery gets discharged trying to start the engine and then it starts, the charge will go to the start battery until it gets somewhat charged before combining them. If you house battery is discharged because you left the lights on all night, then when you start the engine it won't take long for the start battery to met conditions if it was fully charged and then the batteries will be connected and the house battery will be charged by the engine and also drain the start battery, and then they will both be charged. If both batteries are down in charge, the ACR will not combine them until the start battery is somewhat charged before combining them.

Like I said earlier, unless you run your motor for hours with a good charger output and with no other drain your batteries will not be completely charged to 100%. The closer to being fully charged the slower the charging goes. A lot of batteries are never fully charged and do just fine. I'm OCD and want my batteries fully 100% charged when I leave the dock, therefore I keep both of my boats plugged into 120V chargers when not being used.

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Tmann, Dennis, and all others......you would think he would have learned to address the group, instead of an individual, by now. Especially with the quality of answers by others.
Garris

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No problem for me. I hope Gmondun is able to implement a system that works for him. We are all happy to help as we can.

Dennis

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Same here, hope he is getting the answers he needs.

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I am with you fellows. The beauty of the site is the contribution of all for all.
Garris