Rewiring batteries, adding switch, help plz

[Cmac2008]

Ok completely new to boats. Got me a 77 champion and I am currently rewiring everything. I am running new wire in the whole boat.it has 3 batteries in it now.

1. Where does the battery switch go on the boat? I suppose around the dash? What batteries do I hook to the switch?
2. Does anybody use an on board charger?
3. What battery do I put my electronics on?
4. Do I have one battery for cranking one for trolling motor and one for electronics?
5. Do I have any clue what I am talking about?

 

[hemi rt]

The switch is usually mounted close to the batteries so you don't have to deal with heavier battery cables as the farther away the switch is from the batteries the heavier the cable will be required. Yes, I charge the starter battery when necessary and let the motor charge the others when the motor is running. There should be a wiring diagram for the switch you have, it should be with the switch when you bought or use the net to get a wiring diagram. I use terminal 1 as the starting battery and terminal 2 for my accessory battery. If you have 3 batteries then you would need a 3 battery switch. When I have the engine warmed up I put the switch to all which connects the 2 batteries together and charges both. If you have a trolling motor you may want to put the charger on that battery but remember do not hook the charger to more than one battery at a time or you will defeat the switch as some battery charges do not have sense to tell how many batteries are hooked to it and make sure you turn the switch off when not using it which will disconnect the batteries from the boat.

 

[fishrdan]

1- As close to the engine as possible.
2- Yes, highly recommended so you can charge the batteries easily. If batteries are difficult to charge, they won't get charged often. batteries left discharged will lead to their early death.
3- Engine start battery as electronics are a low power draw. (Stereo is different.)
4- What is the trolling motor voltage? If it's a 24V trolling motor you need 2 batteries wired in series dedicated to the trolling motor.
5- Yes - since you are asking the right questions......

- Where are the batteries currently located, all at the stern or the trolling motor batteries at the bow?
- Buy your wire, cable and terminals from genuinedealz dot com. Real "marine grade" tinned wire at big box store prices.
- Use Blue Seas DC wire calculator (google it) to figure out what sized wire/cable you need.
- What is the engine/outboard? (I/O's have higher charge capabilities.)

There are many ways to wire it up, depends on how complicated you want to make things. Easiest is to wire the engine and helm to the start battery, and then trolling motor batteries to trolling motor separate. From there it gets more complicated; battery switch, charger, proper sized cables for the load and distance, etc.

Mysefl, I have 4 batteries a 24V trolling motor and can charge all of the batteries on the water while running the main engine, not a simple wiring job...

 

[Cmac2008]

Thanks for all the info! It us a 12v trolling motor so I will designate it to its own battery. As far as my motor it is only a 25 mercury but eventually will get a bigger motor. I have all the wiring ready to go up to my batteries. Ie I'm wired to my fuse block then I have 8ga coming out of it and I'm dead in the water. All my batteries are in the stern of my boat. I see where the old battery switch went so I will be using that hole. So I need to get me a 3 Bank battery switch. I have a stero and I would like to add a subwoofer and amp so would you recommend a battery designated just to all my electronics? Would that mean I need 4 batteries total? Thanks again

 

[gm280]

Cmac2008, good to see you asking the right questions before jumping into everything. Most don't and then have issues. The only thing I will add to the advice already given is, make certain you use marine grade wire(s). Marine grade wire is tinned coated wire that helps to keep corrosion abated. It will last longer and keep connections cleaner with proper maintenance. There is a difference and for a good reason too. Second, make a wiring list and schematic diagram and plan your layout before starting the wiring. In fact post your schematic diagram on here for everybody to see and if there are any issues, we will explain them before you wire. It can make your wiring project go smoothly without issues. :thumb:

 

[JASinIL2006]

Good advice so far. I would add a couple of things. Buy your wire/cable from a company that does marine cables (fully tinned, as already mentioned) and with lugs/connectors attached. I used these guys and they do nice work for a reasonable cost: https://www.genuinedealz.com/

Another thing: consider carefully where your switch will be most useful. If you trailer your boat, it's nice to be able to reach the switch without having to climb fully into the boat. It's also a good idea to put it in a location where it won't have water dripping on it, or require you to reach around hot engine components, etc.

Put your switch where it's most useful, even if it means buying a few feet more cable or using a heavier gauge.

 

[Cmac2008]

I'm actually buying all my wire and equipment from iboats. I have found cheaper on other sites but it's very convenient and has everything I need in one place. Here is an attachment of the wiring diagram I'm using as a reference I am pretty much following it with a few adjustments.

 

[hemi rt]

The diagram you posted is just normal boat wiring and not a multi battery set up.

 

[Cmac2008]

Yes I know that's why I said Imy good back to the battery and that is where I need the help.

 

[gm280]

Cmac2008, you do know iboat members get a discount from iboat store I hope. Just saying.

 

[Cmac2008]

As I dig a little more I'm understanding a little better. What my plan is as of now is just have a switch for my running battery and starting battery. My trolling battery will be just for the trolling motor? Is this common practice?

 

[Cmac2008]

No Title

I'm also thinking somthing like this. Maybe sticking with just two batteries and following this diagram. It has everything I'm going to have.

 

[fishrdan]

Post up a pic of your boat, when you said 77 Champion I was thinking 18' fiberglass or something of the sort, but the 25HP OB is throwing me (125HP?). Amp, sub, 3 batteries, etc,etc. That's a LOT for a 25HP OB. All the batteries in the stern might be an issue with making the boat stern heavy, depends on boat.

Batteries in the stern and you'll need 6-8ga wire for the TM, battery at the bow and you might be able to wire direct. Depending on how long you run the TM, and the size of battery, you may need dual batteries in parallel for the TM to work for more than a couple of hours (continuous).

If you are going to run a stereo and amp, I would just make a "house" bank and tie the high loads to it; trolling motor and stereo. When they batteries are depleted the fun is over. FWIW, an amp is going to drain the batteries, not like a car/trunk with a big alternator.Same can be said for the trolling motor.

 

[Cmac2008]

Post up a pic of your boat, when you said 77 Champion I was thinking 18' fiberglass or something of the sort, but the 25HP OB is throwing me (125HP?). Amp, sub, 3 batteries, etc,etc. That's a LOT for a 25HP OB. All the batteries in the stern might be an issue with making the boat stern heavy, depends on boat.

Batteries in the stern and you'll need 6-8ga wire for the TM, battery at the bow and you might be able to wire direct. Depending on how long you run the TM, and the size of battery, you may need dual batteries in parallel for the TM to work for more than a couple of hours (continuous).

If you are going to run a stereo and amp, I would just make a "house" bank and tie the high loads to it; trolling motor and stereo. When they batteries are depleted the fun is over. FWIW, an amp is going to drain the batteries, not like a car/trunk with a big alternator.Same can be said for the trolling motor.

Yes fishrdan it is a 17' fiberglass. Currently I have no motor on it but I am keeping an eye out for a 90 or so. I have a 25 that I may put on it just barge to my fishing holes but it would only be temporary. New baby, new house, new job = no boat motor money. Anyways what I'm thinking now is maybe putting two batteries in parallel to run my trolling motor and stero. Then put my other electronics on my cranking battery? I'm just starting to get a grasp of what needs what and where. So total of 3 batteries?

 

[Silvertip]

Here is a novel idea! 1) You don't need a switch at all regardless which engine you eventually install. 2) Your 25 HP motor will barely keep the starting battery charged much less three. 3) You need only two batteries (one dual purpose for the engine and the biggest deep cycle you can afford for the troller). If you already have three batteries, save one of them and try using the largest. If you are an all day fisherperson and don't return to the dock during that time, you may be forced into a two-parallel situation but try just one first. A 75 - 90 HP Merc only has a 16 amp alternator and that's at WOT. So think about this. Assume you have a 50-# thrust troller. That motor draws about 45 amps worst case each hour. Yes - slightly less at lower settings. So you already have a three to one discharge/charge rate imbalance. Run your troller at a fairly fast setting for one hour and you need to run that 75/90 HP motor WOT for three hours to replace that current. Your best bet is to simply install an on-board one or two bank charger. Use the single bank on the troller battery. The engine will take care of the starting battery unless you go nuts with a high power stereo. If you still feel the need, use a two bank charger with one bank for the troller battery and the other for the starting battery. Plug in at the dock whenever you are there, or at home when the boat is stored. Put your electronics on the starting battery. You do not need a three bank charger for a three battery system if two of them are paralleled. The two batteries generally equalize so the single bank of the charger thinks it is charging one big one. It obviously takes twice as long to charge that way so the charger must be sized accordingly but it does eliminate the expense of a three bank unit. And lastly, I simply do not understand the need for a high power amp on a boat considering all the worry about dead batteries, added wiring issues, switch issues, etc. Yes -- I'm a duffer with perfectly good hearing (unless you ask my wife). I would bet the response would be "so I can hear the music at high speed." That may seem like a valid reason for an amp but everyone around you (other boaters and property owners) can hear it as well. On the other hand I recognize it is your boat and your equipment so have at it and enjoy.

 

[bruceb58]

My 90 HP merc is rated 25A @ 5000 RPM and 20A @ 1000 RPM but even that won't charge up batteries you are going to use for a trolling motor. I have 2 batteries on my boat, a start battery and a deep discharge battery that I use for everything other than the motor. It is able to keep everything charged for what I use on the boat but I don't have heavy hitters like a stereo with an amp and music isn't played very loud. Just LED lighting, stereo and a fish finder.

I use a BlueSea switch that turns on both batteries to their respective loads and an ACR between the batteries.

Personally, in such a small boat as yours, I would just have a switch that turned on/off a start battery to your engine. If you wanted batteries for a trolling motor, they would be totally separate and not even tied into the gas motor at all.

 

[fishrdan]

As others have mentioned, you don't "need" everything in the wiring diagrams, sure they are nice, but not must haves. An appropriate sized outboard, I would say that's a must have, and would come before all the bells and whistles.

If you have a mutli-stage battery charger for your car/truck, nix the onboard battery charger for now and use the portable charger. I use one for my jon boat's batteries as the boat is in the garage, it's easy enough to connect and use. (My other boat would be a royal PITA to use a portable charger as the boat is outside and covered, and has 4 batteries...)

I like your plan of figuring out what you want, so when you buy something it fits into the grand scheme of things.

Also, you mentioned kids... Be sure to put a plug on the trolling motor so you can quickly and easily disconnect it when not in use. Wouldn't want any accidents with little ones playing on the boat and hitting something. TM prop could cause some serious injuries.

 

[Cmac2008]

Ok guys I got some good news! Found a 80hp motor for a very fair price! I'm going to che check it out tomorrow... as far as the batteries go I don't want to shortcut anything and this all will not happen overnight due to the total boat remodel, money, family time. Tell me if I miss anything here but my plans are a battery (maybe 2) for the TM and amp,subs. If i am fishing i would not be using my amp and subs and if i am just hanging out on the lake i wont be using my TM. A start battery and a battery for stereo, electronics, and everything els. My question is will a battery charger still benefit me? I would like more info on a onboard charger installed on my boat. Will the charge rate be more than what the motor can do. If the motor is off will the charger still charge? I guess I'm just not too sure how they work. My switch will not be hooked on to the TM/amp battery.

 

[bruceb58]

You plug your onboard charger into 110VAC when you are done with your boat so your motor isn't on then right?

 

[km1125]

The charger helps when your motor can't replenish the batteries under normal use. You don't want batteries to sit in a partial-discharged state or they will loose capacity quicker. As someone else said earlier in one example, your motor would have to run for three hours for each hour your trolling motor was running. That just a rough guess, as no one had specifics, but a good example. Normally, your motor will refresh the batteries from normal engine starting and normal electronics like a chartplotter or fishfinder. A trolling motor/battery can take a lot of capacity and most motors can't dish that out unless they are running for a while, so that's where a charger really comes into play. All depends on your usage pattern.

Putting a big load on an engine charging system can be an issue too. The system might be rated for a max 15 amps or 25 amps, but you have to be careful running it at that load continuously. You might end up burning up a charging circuit or alternator doing so, as they are really not built to handle the heat that will build up.