Category Archives: Trolling Motors

Still have that receipt?

Hi Kevin,

Just purchased the 2501 battery isolator for my boat. Going to use a two battery system, one for starting, and the other for trolling motor and accessories. I have an outboard mercury 70 hp motor.

Do I need to come directly from the alternator to the isolator on terminal A? If so, how is that done? And do I use the existing alternator wire, or add a wire from the alternator?

Thanks!

Paul

Paul,

You need to connect the isolator directly to the alternator output. The alternator sense wire needs to be connected to the positive post of one of the batteries. This can be difficult with an outboard motor and impossible on some models.

I would strongly recommend returning the 2501 battery isolator and purchasing a VSR based automatic smart boat battery switch. This unit will allow you to charge two batteries with your motor, but does not require you to connect to your alternator output. The VSR connects between the positive battery posts and monitors the voltage on each battery. Your outboard motor connects to one battery and your boat accessories connect to the other. The grounds are tied together.

Hope this helps,

Kevin

Plug Polarity Problem?

Kevin,

I bought the Marinco Connect-Pro trolling motor plug and socket set about a year ago and am just getting around to installing it.

Unfortunately I don’t have the paper instructions any more.

I see the terminals are marked 1, 2 and 3. I have a very small 12 volt trolling motor, and will only use two wires, red and black. Marinco Connect-Pro Trolling Motor Plug

Looking at the design of the plug, I think I’ll be using terminal 1 and terminal 3 and leave number 2 unused. My question is whether the red positive lead should use terminal 1 or 3.

Thanks for your consideration.

Dave

Dave,

It doesn’t matter which terminal you use for + and which one for -, as long as you use the same wiring arrangement on both the plug and receptacle. My preference on the Connect-Pro system is to use terminal 1 as ground, terminal 2 as +12 volts, and terminal 3 as +24 volts.

Happy boating,

Kevin

Reconnect Batteries in Series?

Kevin,

I have a foot controlled trolling motor with a toggle switch to go from 12 to 24 volts. I have a plug at the trolling motor that runs back to two 12 volt batteries that are not wired in series and I also have a three-bank battery charger for starting battery and both trolling batteries.

The trolling motor will only work when toggle switch is set to 12 volt. Do I need to wire the trolling batteries in series?Attwood battery boxes are safe and economical

Thanks,

Ron

Ron,

How many wires are in the trolling motor plug and wiring?

  • If there are 4, the system is designed to use the 12/24 volt switch to switch the trolling motor from parallel 12 volt to series 24 volt. Something is wrong with the switch or wiring that is preventing this parallel to series conversion.
  • If there are 2 wires, the 12/24 volt switch will not work. The system will either be 12 volts or 24 volts and cannot be controlled by the switch. Connect the batteries in series to run your motor on 24 volts.
  • If there are 3 wires, the 12/24 volt switch is designed to switch between 12 volt single battery and 24 volt series battery. This system requires a jumper between your two trolling motor batteries.

Hope this helps,

Kevin

Using 12 Volts of a 24 Volt System

Kevin,

I bought a 24v trolling motor.

When I wire the motor using a 24 volt connection, does that preclude me from using those same two batteries to power other 12 volt applications, such as a power anchor? MotorGuide builds the world's finest trolling motors

Thanks.

Doug

Doug,

You can certainly still use the same two batteries to power other 12 volt applications.

Be extremely careful when connecting items to the battery that represents the 12 to 24 volt portion of your trolling motor system. I would recommend circuit protection for the negative leads of 12 volt devices connected to this battery.

For example:

You have an aluminum boat. You connect your power anchor to the 12 to 24 volt portion of the trolling system. Your main engine is connected to the the 0 to 12 volt portion. The engine bolts to the transom. Now the entire boat is grounded.

Suppose that something happens to your power anchor and its power and ground wires short to the hull. The fuse on the positive lead for the power anchor blows. The negative lead doesn’t have circuit protection and it causes a dead short through the hull, through your main engine, and back to the negative of your 0 to 12 volt battery.

Let me know if you have more questions,

Kevin

Kevin,

Thank you for the prompt rely.

I have a separate battery for the motor, so hopefully this will simplify things. Are there any concerns I should have with battery chargers wired to each battery?

Thanks.

Doug

Doug,

Make sure your battery charger is designed to charge a 24 volt marine electrical system.

A dual-output charger with only a single ground will not work. Each charger output needs to have a separate, dedicated ground.

Kevin

Adding a 24 Volt VSR

Hi Kevin,

I’ve just purchased my first boat and am setting it up with a 24 volt trolling motor and an on board charger. After seeing all the boat wiring info on your site, I just have a couple questions to make sure that I get it right.

  1. If I’m installing a VSR do I need a two or three bank charger for charging my batteries with shore power? I have two deep cycles for the trolling motor and one cranking battery for starting my big motor.
  2. I would also like to install an on/off battery switch, so when the boat is not in use, everything is shut down. Where should this be placed in the marine electrical system?

Everything else seems straight forward after visiting your site.

Thanks for all the info!

Charlie

Charlie,

There are two types of VSRs.

12 Volt Systems

The VSR is connected between the positive posts of two batteries. The negatives are connected together. This type of VSR works great for multiple battery systems that have a common ground and only operate at 12 volts.

24 Volt Tolling Systems

In this case, the VSR is the only connection between the 24 volt trolling motor batteries and the 12 volt engine battery. This type of VSR charges battery 1 of the trolling motor system for 1 minute and then charges battery 2 of the trolling motor system for 1 minute.

For your marine electrical system, I would recommend the 24 volt VSR. You could use the 12 volt unit to charge one of your trolling motor batteries, but the second trolling motor battery would only be charged by the battery charger.

I would also recommend a three bank battery charger.

Size your charger based on your desired recovery time of your trolling motor batteries. (Decide of you want a few hours, overnight, or 2 day recharge time) The charger output to the engine battery can be minimal (3 amps). It is more of a maintenance charge than a recovery charge.

As for the battery switch,  install an On/Off Battery Switch near your starting battery. Connect all emergency circuits to the battery side of the switch (bilge pump, horn, etc) and connect non-essential circuits (nav lights, docking lights, etc) to the non-battery side of the switch. Connect your existing engine battery cable to the non-battery side of the switch.

Let me know if you have any more questions,

Kevin

Hi Kevin,

Thank you for your quick reply.

I just have one other question. Do I hook my on-board charger directly to each of the three batteries, independent of the cables with the VSR?

Thanks,

Charlie

Charlie,

The charger connection points will depend on where you are mount the charger and the type of wiring it comes with.

One option is to connect the charger directly to each battery. Another option is to connect the charger at the VSR. The Trolling VSR has three sets of wires that lead directly to each battery. A third option is a combination of these two ideas.

My preference is to only have one positive and one negative cable connected to each battery post. I realize this is not possible for some applications, but the more you can reduce the confusion and clutter when reconnecting batteries, the better your marine electrical system will be.

Kevin

Hi Kevin,

I have purchased all of my boat wiring components and am ready to install.

I just have two other questions before I start, so I get it right the first time.

  1. For leads from the starting battery, do they go from the battery to the switch then the VSR and then the motor? Or, does one set goes to the VSR and another to the motor via a switch? As you recommended, my on-board charger will attach at the VSR for all the batteries.
  2. I am having a hard time finding 70 amp fuses or circuit breakers, so is it OK to use 50 amp ones?

Thanks for all your help!

Charlie

Charlie,

  1. The leads from the starting battery go to the switch. Two sets of wires leave the switch. One goes to the motor and one goes to the VSR (through your circuit protection).
  2. 50 amp will work fine. If your engine alternator is large enough, you may have a nuisance trip problem with the circuit protection on the lead between the VSR and the battery switch.

Let me know if you have any other questions,

Kevin

Batteries to Stern

I am wiring up a boat.

In the bow, I have a group 27 deep cycle battery that is for the bow mount and depth finder. In the back I have a group 27 deep cycle/starting. This battery is used for starting a 25 hp boat motor and depth finder. BEP offers ignition protected fuses for your boat wiring project

Last night I was wiring up the bow battery to the back of the boat so I can use a transom trolling motor. I am wiring this up with 6 gauge wire.

Could I just wire the two batteries in parallel and then run 6 gauge from the deep cycle/starting to the transom trolling motor, and than have the other cable go to the gas motor? Can you see any benefit to doing this or should I stick with the game plan of running directly from the bow battery to the transom trolling motor.

Thanks in advance.

Todd

Todd,

My main concern is circuit protection.

For your trolling motor circuits, you should have circuit protection as close as possible to the battery connection. If you are connecting the two batteries together in parallel and one battery is in the bow and one in the stern, you should really have circuit protection at each end of the positive lead between the two batteries.

If you boat can handle the weight, I would put both batteries in the stern near the 24 hp motor.

Connect them in parallel with the same size wire as the engine cables on your motor. Install circuit protection in the positive leads of both trolling motors as close as possible to the battery bank. If the batteries are not in an area that needs ignition protected devices, MAXI fuses work great for this application. If the batteries will be in the engine room or near gasoline storage, you will need ignition protected circuit protection like an ANL fuse.

Hope this helps,

Kevin