12/24 volt discharge problem

[meathunter]

I have seen previous posts on this but was wondering if someone could help me? My problem is my minnkota 24 volt trolling motor draws off of one battery and not the other. Every time i use my onboard charger the green lite (fully charged) is on for one side and the chargeing lite is on for the other. In order for my motor to work i have to have the power hooked up to both batterys seperate. The boat i have is a alumacraft tourn. pro with factory wireing. There is two sets of wires for my bow mount. Not real sure on what to do here but i just purchased a new battery for one side and had the other one checked so this is not a battery issue. Although the one battery is bigger than the other. Any comments appreciated.

[gonecribbin]

Ive been told that you arent supposed to mix and match batteries of different brands or ages, they may interact poorly and damage each other. Also batteries have to be hooked in a series, positive to negative on the 2 batteries.

[randallt]

I am sure you already tried this, but maybe the one set of wires is for a 12volt motor and the other is for a 24v, maybe try switching them. The other important thing is to connect the two batteries correctly. There have been some good diagrams on here about that. But basicly you connect the Pos to the Pos terminal on bat 1 and the negative wire to Neg terminal on Bat 2. Then you connect the Pos Term on Bat 2 to Neg on Bat 1 with a bridge wire.

I hope that makes sense and I am not way off on your question. If all else fails run it into a marine, most will take a quick look at no charge to make sure it is not a simple fix.

[meathunter]

I have been looking on this forum and have read about a diagram for hooking up 12/24 volt systems does anyone know how i can view this?

[BobT]

Be careful about hooking multiple batteries together. If you are not sure what you are doing, you could damage your electronics. No disrespect intended but in the two previous posts the result of their suggestions would be totally different.

Connecting two batteries in series (Pos from battery A to the Neg of battery results in two potentials with one of them being the combined total of the two. The potential between the Neg of battery A and the Pos of battery B would be 12v + 12v = 24vdc while you could still acheive 12vdc potential from either battery by itself.

Connecting the batteries in parallel (Pos of battery A to Pos of battery B and Neg of battery A to Neg of battery will result in only 12vdc potential only but does combine the capacities of the two batteries. This system is like having one very large battery.

This is very difficult to explain in text form without diagrams so if you don't understand it is best to get help from someone that does.

Bob

[meathunter]

After doing some digging i found out i have 2 batterys with 2 seperate positive and negitives that go to a plug that says is a 12/24 then my trolling motor plugs into that i dont believe that my trolling motor is 24 volts although it does not say. This motor was bought used and is probably 8 to 10 yrs old but still works good. Does anyone know if this hook up makes 24 volts? With this type of wireing why dont the batterys drain evenly and will one have to drain down before the other one draws or what? I have yet to have problems with power went about 4 to 5 hours in a good wind the other day and when i plugged in the onboard the only battery to take a charge was the smaller battery. If the different size is an issue any ideas on how i can run these cause i dont have any use for the odd size and would like to burn it up. would switching terminals make a difference?

[Whoaru99]

Quote:

---

After doing some digging i found out i have 2 batterys with 2 seperate positive and negitives that go to a plug that says is a 12/24 then my trolling motor plugs into that i dont believe that my trolling motor is 24 volts although it does not say. This motor was bought used and is probably 8 to 10 yrs old but still works good. Does anyone know if this hook up makes 24 volts? With this type of wireing why dont the batterys drain evenly and will one have to drain down before the other one draws or what? I have yet to have problems with power went about 4 to 5 hours in a good wind the other day and when i plugged in the onboard the only battery to take a charge was the smaller battery. If the different size is an issue any ideas on how i can run these cause i dont have any use for the odd size and would like to burn it up. would switching terminals make a difference?

---

This type of wiring is fairly common on a 12/24V system.

Each battery is separately wired to the receptacle, and a jumper (or jumpers) inside the male portion of the plug (the end on your trolling motor) determines whether the motor receives 12V or 24V.

The brand on my boat is Marinco so that is my example material. If you look at the pictures below, you will see two different versions of the plug. One is 12V only and has both batteries in parallel through the jumpers. The other plug is a 12/24V plug and has the batteries jumpered in series, but with a hole that allows you to tap off 12V from one of the batteries. The latter arrangement is likely similar to how your plug is set up.

The plugs in the pictures are both oriented the same way with respect to the keyed terminals/contacts so you can see exactly how the jumpers differ.

And, here is a battery connection/pinout diagram that corresponds to the pictures above.

Using a 12/24V plug will never allow you to use both batteries simultaneously to one 12V device unless you remove the existing jumper and modify it to be like the 12V-only plug. That is the reason one battery is always charged and why the run time is less than you are expecting - only one battery is being used.

Alternatively to modifying the plug you have, is to buy a 12V only plug. Sometimes the 12V-only plugs are called "charging plugs" as in the case of the connection style used on my boat, like this one pictured here.

[Satchmo]

What model of trolling motor do you have? If it is a 24 volt motor you are not getting the correct voltage to it if only one battery is discharging. If it is a 12 volt model you will need the red charging plug to be able to pull juice from both batteries simultaneously. I would bet that the trolling motor plug is wired incorrectly. If you are using the marinco style plug, you must also be sure to tighten down any loose screws inside the plug that are not being used. This anchors the jumpers and can prevent some serious damage from things shorting out in the plug.