Another Dual battery question

[boater83]

Searched a few topics but didn't seem to find my answer. I have a dual batteries with Perko switch selector. The batteries are the exact same. Question is when starting an engine, should I turn to DUAL or choose a battery randomly. Once started, can I leave it in DUAL to charge both batteries while I am on water? Which way is better life for the batteries?

I am worry if I always choose battery "A," the other one will not get much usage and doesn't hold well.

 

[tpenfield]

Re: Another Dual battery question

You can do what ever you like with those batteries.

I always put mine to 'Both' (Dual) and leave it there. My thoughts are you get double the source for starting and you keep both charged up when you are running the engine.

I rarely, if ever go to just one or the other.

Of course, there was the time when I forgot to turn them to "Off" and somehow drained them "Both", :facepalm:

 

[boater83]

Re: Another Dual battery question

You can do what ever you like with those batteries.

I always put mine to 'Both' (Dual) and leave it there. My thoughts are you get double the source for starting and you keep both charged up when you are running the engine.

I rarely, if ever go to just one or the other.

Of course, there was the time when I forgot to turn them to "Off" and somehow drained them "Both", :facepalm:

I always thought your idea was the right way. I did read somewhere advising not to do that that, maybe it was due to two different batteries or something, not sure.

 

[flingus]

Re: Another Dual battery question

I always thought your idea was the right way. I did read somewhere advising not to do that that, maybe it was due to two different batteries or something, not sure.

May depend on how you use them.. I use 1 battery mainly for starting, and another deep cell for once I've anchored somewhere and kick on the radio and relax for a bit. So for example, I set my switch to ALL when I start it and am cruising around the lake.. Then switch to battery '2' once I kill the motor and anchor.

 

[rickryder]

Re: Another Dual battery question

May depend on how you use them.. I use 1 battery mainly for starting, and another deep cell for once I've anchored somewhere and kick on the radio and relax for a bit. So for example, I set my switch to ALL when I start it and am cruising around the lake.. Then switch to battery '2' once I kill the motor and anchor.

X2 I do the same thing....start on #1 switch to all while getting where I'm going to charge them,switch to #2 for hanging out fishin
At least I know my starter battery will have a charge when it's time to move on

 

[Jlawsen]

Re: Another Dual battery question

If the batteries are exactly the same then running it in "Both is the same as running them in parrallel and your gain is that your total battery capacity is doubled. In the #1 position the first battery is providing it's rated capacities to your boat with some loss due to starting. That is usually recovered quickly by the engines charging system. Battery #2 is doing nothing and remains fully charged but without an ACR circuit it recieves no benefit from the engines charging system.

In that type of scenario your #1 battery is your primary and #2 is your reserve. In order to be sure that #2 is an untapped reserve energy source make sure you move any direct battery taps for accessories to the "Common" post on your switch. If you don't you may find that critical circuits don't work when you change switch positions or that your reserve battery is dead when you need it most.

There is a better solution - Blue Sea makes a "Add a battery" kit that includes a switch and an automatic charging relay (ACR). I get them for 139.00 and they come with very complete instructions. The kit takes all the guess work out of it. You simply put the switch in positon 1 and go. If for some reason you need both batteries at one time, you can put it in both mode also which is a little reasuring. The ACR controls the output of the engines charging system by directing the charging current to the most critical #1 battery first. When it senses the appropriate voltage level on #1 it switches and charges #2. If #1 falls below acceptable limits it will switch back to #1 even if #2 is not fully charged. There's no way you're going to be able to do that manually which is what makes these units such and exceptional add-on.

When charging batterys with an ACR circuit you can connect a conventional charger to either battery. There is one warning and that is if you are using a more modern digital charger that samples the battery being charged it will take that reading from whatever battery the ACR is set to. When that battery is fully charged the ACR will switch but the charger won't know this and will be in mainteneance mode which will make for a long wait. It will bring it up but at only about a 2 amp charge rate. My preference is to disconnect the batteries and charge them off circuit on the bench where I have plenty of ventilation.

 

[boater83]

Re: Another Dual battery question

Thanks for the info.

 

[Silvertip]

Re: Another Dual battery question

Most folks tend to overthink the dual battery switch and are paranoid about perhaps having a dead starting battery. Fact is, set the swtich to BOTH and go boating. Under 90 percent of the circumstances you will never end up with a dead battery. If you have a high power stereo system or other very high current draw items on the boat AND you tend to anchor for extended period, then and only then would it be wise to switch to BAT 2 (the house battery) to protect the starting battery. When you get ready to leave you have a choice of switch settings. Chances are the house battery will still start the engine so why not leave the switch set to BAT 2 so that it gets the full charge on the run to wherever you are going next. You know BAT 1 is ok because it hasn't been used. If you tend to stop for an hour or less, even with high current draw items, leave the switch on BOTH. Start and go at which time BOTH batteries charge. So you see, there is no need to continually fiddle with the switch. As for ACR's, if you are "switch challenged" (can't seem to figure out when to use what setting) then add the ACR. They are fine devices but add complexity and one more potential point of failure. Keeping electrics simple can help avoid electrical issues.

 

[palace]

Re: Another Dual battery question

Yes you can run on both but if your alternator is not capable of handling the load....new alternator. If you batteries are not at same charge the lower charged battery will drain the higher charged one to balance them out. If you really want to run on both then you should install an ACR with your existing perko switch. The only reason for both is if your starting battery starts to crap out you can switch to both, to get home. I personally will start out by topping off both batteries the night before. Launch on my starter bat. once I anchored for a while use my #2(deep cell) for the rest of the day.

Searched a few topics but didn't seem to find my answer. I have a dual batteries with Perko switch selector. The batteries are the exact same. Question is when starting an engine, should I turn to DUAL or choose a battery randomly. Once started, can I leave it in DUAL to charge both batteries while I am on water? Which way is better life for the batteries?

I am worry if I always choose battery "A," the other one will not get much usage and doesn't hold well.

 

[Linecoach97]

Re: Another Dual battery question

I've had my fish finders and stereo drain my batteries twice while on the ocean, NOT A GOOD TIME! At the time I was running the stock 55amp alternator and a standard 3 position Perko switch. Not ideal in my opinion. I was doing like you have mentioned and running on "both" most of the time. I know that the #2 battery was never really receiving the full charge of my alternator. I know this because I would test the charge at home after a day on the water and it was always low and I would have to recharge it. My alternator finally gave out. I'm not certain if it contributed or not, but I believe the constant draining and recharging of the batteries eventually lead to my alternator petering out. I have since replaced the stock alternator with a 105 amp, single wire, and a Blue Sea ACR, and I replaced the Perko switch with a Blue Sea dual circuit switch. Both came together as part of the "add a battery" package ($129 on Ebay). With the extra alternator output and the dual circuit switch The ACR will charge each bank separately, as needed, automatically, and have plenty of juice to spare for my electronics. I run two deep cycle marine batteries and use one isolated for starting and the other to power the electronics. The nice thing about these Blue Sea systems is that all you really need to do with the dual circuit switch is turn it to the "on" position and the ACR does the rest automatically. They are simple to use with only an "on", "off", and "emergency/combine" setting on the switch. Fairly inexpensive system as well, with a total cost of less than $200 (not counting batteries). You might want to check these out and see if they are something that would work for you. Happy Boating!

 

[Silvertip]

Re: Another Dual battery question

Yes you can run on both but if your alternator is not capable of handling the load....new alternator. If you batteries are not at same charge the lower charged battery will drain the higher charged one to balance them out. If you really want to run on both then you should install an ACR with your existing perko switch. The only reason for both is if your starting battery starts to crap out you can switch to both, to get home. I personally will start out by topping off both batteries the night before. Launch on my starter bat. once I anchored for a while use my #2(deep cell) for the rest of the day.

You also misunderstand the versatility of the switch. You indicate that the ONLY reason to use BOTH is if the start battery begins to crap out you switch to BOTH to get home. 1) If the engine is already running the START battery is not about to crap out. 2) If the start battery has an internal issue where it cannot keep the engine running, BOTH is NOT the setting to use. BAT 2 is the proper selection. Every tried to jump a stone dead or a bad battery? They simply will not accept a jump. The switch provides the ultimate in versatility in that you can start the engine on 1, 2, or both, you can power all accessories connected to the COM terminal by 1, 2, or BOTH and you can charge 1, 2, or BOTH. You are also mistaken about batteries equalizing when running. Ain't going to happen. They will equalize when not being charged if one battery is in significantly poorer condition than the other. Again, that's an owner issue, not a fault of the system. Obviously if you have an alternator that is not fit for dual battery service you need another plan but that's not a fault of the switch but rather an owner/installer issue. Lastly, dissimilar battery capacities (24 & 27 for example) can live side by side just fine and can be charged just fine. For heavens sake over the road trucks can have six batteries in parallel and they are not replaced as an entire set when one goes bad. They also obviously charge just fine dispite the fact that they are not the same age or exactly the same capacity.

 

[Stephen Burgin]

Re: Another Dual battery question

If the batteries are exactly the same then running it in "Both is the same as running them in parrallel and your gain is that your total battery capacity is doubled. In the #1 position the first battery is providing it's rated capacities to your boat with some loss due to starting. That is usually recovered quickly by the engines charging system. Battery #2 is doing nothing and remains fully charged but without an ACR circuit it recieves no benefit from the engines charging system.

In that type of scenario your #1 battery is your primary and #2 is your reserve. In order to be sure that #2 is an untapped reserve energy source make sure you move any direct battery taps for accessories to the "Common" post on your switch. If you don't you may find that critical circuits don't work when you change switch positions or that your reserve battery is dead when you need it most.

There is a better solution - Blue Sea makes a "Add a battery" kit that includes a switch and an automatic charging relay (ACR). I get them for 139.00 and they come with very complete instructions. The kit takes all the guess work out of it. You simply put the switch in positon 1 and go. If for some reason you need both batteries at one time, you can put it in both mode also which is a little reasuring. The ACR controls the output of the engines charging system by directing the charging current to the most critical #1 battery first. When it senses the appropriate voltage level on #1 it switches and charges #2. If #1 falls below acceptable limits it will switch back to #1 even if #2 is not fully charged. There's no way you're going to be able to do that manually which is what makes these units such and exceptional add-on.

When charging batterys with an ACR circuit you can connect a conventional charger to either battery. There is one warning and that is if you are using a more modern digital charger that samples the battery being charged it will take that reading from whatever battery the ACR is set to. When that battery is fully charged the ACR will switch but the charger won't know this and will be in mainteneance mode which will make for a long wait. It will bring it up but at only about a 2 amp charge rate. My preference is to disconnect the batteries and charge them off circuit on the bench where I have plenty of ventilation.

I have two 12V car batteries. Should I have two marine deep cell batteries?[/QUOTE]

 

[Stephen Burgin]

Re: Another Dual battery question

Another question: I have two batteries and a Johnson, 200hp 2 stroke, outboard; but I believe the batteries are not deep cycle batteries. Should I have only deep cycle and should both batteries be the same (in other words, not one that is deep cycle and the other one not deep cycle)?