Converting 12/24V to 24V

[redskeet100]

Hey guys. CAn you help me. I have a 1997 Lund that was wired for a 12/14 Trolling motor. I have since upgraded to a 24 Volt and want to wire it accordingly. I have replaced the 12/24 plug that attaches to the TR with a 24V plug. I have a 4 wire plug that the TR plugs into that runs to the batteries. Here is my setup:

Plug has 4 wires, red, black, orange and black\blue. somehwere between the plug and the batteries, all four of these split into 2 cables. So at the batteries, I have 2 orange going to pos on battery 1 and 2 black\blue going to neg on battery 1. Going to battery 2 I have 2 red to the pos and 2 black to the neg.

So to hook up the batteries for 24V, I need to run the red to pos on battery 1, the black to neg on battery 2 and a jumper from neg on battery 1 to pos on battery 2. Since there are 2 reds and 2 blacks, do I hook them both up? I have read that I can get rid of the orange, what about the black\blue? Thanks in advance.

 

[Silvertip]

Re: Converting 12/24V to 24V

As long as you have one negative and one positive (+24) wire going to the receptacle that's all you need. The other wires aren't needed. HOWEVER!!!!!!!!!!!! I suspect those doubled up wires were there because one one alone was not big enough for the current draw so the question is -- What gauge wire does this system have. You should very likely have 6 gauge wire minimum. If that's the case, then the others are not needed. If the wires are smaller than 6 gauge, then you need to 1) replace the -24 and +24 wires and 2) the jumper with 6 gauge, or pair up all three of those (two smaller wires = one bigger one). My suggestion is to to not butcher this system by removing wires. The next owner will not appreciate you. Just use two wires that you already have and pair them if necessary. Match the +24 and -24 pins on the receptacle to the corresponding pins on the plug.

 

[Thrillz]

Re: Converting 12/24V to 24V

Silvertip,
I had a similar issue today, I removed a 12V Motorguide 50lb bowmount and installed a used Minn Kota 80lb Co-pilot/Auto Pilot/US in it's place. The plug was an 8 AWG with 4 wires; red, black, orange and black/blue. The Minn Kota trolling motor has a simple black and red wire approx. 8 AWG coming from the unit. I cut off the 4 wire plug and capped the black and orange wire. At the batteries I saw the black and blue wire was connected to the negative terminal and the red was connected to positive terminal with a fuse. I created a 6 AWG jumper between the two batteries and used the two just described on the opposite terminals of the jumper. I Connected the matching wires at the bow (hard wired) to the Minn Kota and everything worked great. I am running 8 AWG from batteries to the unit.
Questions:
1. Am I losing volts by using the existing 8 gauge wire? I heard I shouldn't use less than 6 AWG on a 24 volt system. It runs about 10-12 feet.
2. Where do I connect a volt tester to see what volts are put out ?
3. Is a hard wire OK at the unit or should I use a plug/adapter system ? The wire is hidden so I dont care about looks.

Lastly, I also run a transom mount 12 volt - 55lb. Minnkota Endura. If I hook that up to one of the trolling batteries (12V only, I know), how will that affect the overall output of the batteries when running 24V mode if I draw down one more than the other ?
Thanks for your time and knowledge !!!

 

[Silvertip]

Re: Converting 12/24V to 24V

You have a couple of issues. An 80# motor draws 56 amps maximum. If you look at the following chart, you will find that #8 gauge wire in an enclosed area is rated for only 46 amps -- well below the 56 amp max draw. If the cable was in free air it is rated well above the 56 amps. So 6 gauge wire should be used in the entire circuit. Don't know what you mean by adapter but for a 24 volt motor you need only a two wire receptacle and matching plug. Wire the motor cable to the plug and the two wires fromt the battery to the receptacle. You measure voltage at the receptacle but you want to make the measurement with the motor running under load. Last, the 12 volt motor MUST be connected to the battery that has the ground wire going up front. If you hook it to the battery that has the POSITIVE cable going up front you run the risk of creating a serious short if ground on that battery and ground on the troller ever come together (as in through the metal hull). Not a problem on the other battery. Obviously using one battery on a 24 volt system will cut down run time for both motors since both are drawing more from that one battery than the other which is used only by the 24 volt motor.

http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity#Load_Carrying_Capacities_or_Ampacities

 

[redskeet100]

Re: Converting 12/24V to 24V

I believe I may have 8 awg wire. So if I connected the 2 reds and 2 blacks, and used 2 wires as the jumper between batteries, I should be okay?

Also, each wire had a fuse right before the battery. If I install a circuit breaker on the post connection, can I leave the fuses or should I cut them all off? I am assuming it would be better to cut them off.

Also, in your post above, how do you know what the ground wire is? I do not see any additional wires so I am unsure.

 

[rndn]

Re: Converting 12/24V to 24V

There are a positve and a negative coming from the batteries. There is no ground so to speak unlike a house circuit.

 

[Silvertip]

Re: Converting 12/24V to 24V

Ground is -24 volts (the negative terminal of the battery). Here is a picture of a 24 volt series connection. The battery on the left has the -24 volt (ground) wire connected to the negative terminal. Again -- the SEARCH function would have helped you find the answer much faster than waiting for someone to answer you.

 

[Thrillz]

Re: Converting 12/24V to 24V

Well I took Silvertips advise and wired the boat in 6 gauge. I did not use marine grade, I used a more rigid type from Home Depot. I used an aluminum Splicer reducer to make the connection at the motor and it ran great, but I had not heat shrunk the connection yet and they touched !!! A large spark and smoke, they temporarily fused together before I pulled them apart !!! I had a 40 amp breaker on the positive battery connection to the motor. It blew so I took it off and connected the cable directly to the battery. The trolling motor seemed to work fine :redface:. I am going to install a 50 amp fuse to replace the blown one. Did I damage the motor or deep cycle batteries in any way ? The connection to the battery is not tinned, does this mean they are more prone to corrosion ?

 

[Silvertip]

Re: Converting 12/24V to 24V

How did you connect the wire to the battery? Crimped ring terminal or what? And exactly what type of "rigid" wire did you use? THHN perhaps which would be another mistake. And since you used an aluminum splice device on copper wire I would assume you did not know that this creates an oxidation problem unless the joint is protected with "No-Ox" anti-oxidation compound. See why it pays to head advice. You then said the "breaker blew" and later said you will install a 50 amp fuse. So was the breaker a circuit breaker or a fuse. If it was a breaker you don't throw them away -- they reset themselves or they have a button to push to reset them. If it is indeed a fuse, then it is toast. As for damage to the motor -- that is unlikely as the fuse/breaker did it's job.

 

[redskeet100]

Re: Converting 12/24V to 24V

Thanks SilverTip, I had seen that diagram many times, but was unsure if there was an actual additional wire for ground. I think I got it now and will go back and try again this weekend to complete the project.

 

[Silvertip]

Re: Converting 12/24V to 24V

One last word of caution for everyone with a metal hull boat. In this forum there is a discussion about grounding to the hull of the boat. In this example where wire splices are not protected, had the joint in the hot lead touched any metal part of the boat a hole could have been burned in the hull in a heartbeat. Why??? Read the grounding post but the key is that as soon as an outboard engine is bolted to the boat the hull is grounded to the negative post of the battery. A short, as in this case, where the positive joint touched ground would create a problem. A battery is easily turned into an ARC WELDER so pay attention to wiring and unprotected wiring.