12v VS 24v operation

[basster]

This is the first time wiring a trolling motor for me and I am having some trouble. I have a 12/24 motorguide 45lb motor. I have a 12/24 switch on it and it's hooked up to the plug in at the bow where I have another 12/24 switch. The motor currently works on both settings, my question is, Can I run this motor on 24v only by running two cable straight to my batteries and installing the crossover? Can I get rid of the 12/24 switch on my bow? OR do these motors have to be rigged up to use both 12/24. Also, I'm running 8ga what fuse to do you guys recommend I use? THANKS!

 

[Silvertip]

Re: 12v VS 24v operation

It's a shame to mess with the wiring on a boat that is properly set up for a 12/24V troller. You didn't state what the problem is. The reason your motor operates in both 12 and 24 positions is because it is both a 12 or 24V motor. Depends on which you select. Set both switches to 24V and enjoy.

 

[basster]

Re: 12v VS 24v operation

Thanks for your reply...Well, there's really no problem. I just want to replace the existing wiring with new. There's 10 ga in there right now and I wanted to replace it with 8ga. and as it is, I never use 12v, always windy out here. Do you think it's worth it to go though the trouble of connecting both voltages? How would you charge batteries if connected for 24v operation with a crossover?

 

[Silvertip]

Re: 12v VS 24v operation

You can use a standard 12V charger for 24V but each battery MUST be charged separately. If you have an on-board charger it must be 24V capable. Usually these units have two separate and isolated 12V outputs that are connected the same way the batteries are (two 12's in series = 24V). There is no need to go to larger wire. 24V motors draw less current than the trollers of the same power running on 12V. (Read that carefully!)

 

[Mr. Pike]

Re: 12v VS 24v operation

Upinsmoke,<br />You were very helpful on an earlier post I submitted. Thank you. I have one more question for you if you can tolerate it. I did a search, but can't find an answer to my specific question. I have now connected my batteries in series. Bat 1+ to Bat 2-, Bat 1- to TM and Bat 2 + to TM. I have an on board, dual bank charger that is 12/24. Four leads (2 Pos and 2 Neg). How should I connect the charger to the batteries please?

 

[Silvertip]

Re: 12v VS 24v operation

No problem! Think of the two sets of 12 leads as the two sets of POS and NEG posts on the batteries. Run the POS lead from one output (doesn't matter which) to BAT 2 POS. Connect the NEG lead from that output to the NEG terminal on BAT 2. Connect the other outputs to BAT 1 POS and BAT 1 NEG. If you look at carefully, what you've done is connected one POS output to the NEG lead of the other output because of the jumper between the two batteries. The problem with some of the older two-bank chargers is that the outputs were not isolated. That means they had a common ground (but two ground leads). Those won't work in a 24V only system. They were intended for charging two 12V batteries wired in parallel or through the charging plug in your 12/24 system. See why I didn't want you to change anything? Go Fish!

 

[Texasmark]

Re: 12v VS 24v operation

My Motorguide, 61 lb thrust, recently purchased, recommends a 40 amp fuse in each leg of the 24 volt system; one per battery, 2 batteries in series to produce the 24 volts.<br /><br />The manual also mentions the most efficient service is at 24 volts. That's because on the lower speeds the current is less than it would be on a 12v circuit (for the same thrust setting)and since loss is attritubed to current flow, if you double the voltage, for a given work function (speed/thrust whatever) you halve the current and thus halve the loss caused by wire resistance.<br /><br />Mark

 

[basster]

Re: 12v VS 24v operation

Thanks guys, I really appreciate your help. I just got rid of a heavy-duty 12/24/on-off switch on my wiring and I was going to connect the batteries straight without that switch, is that switch there for a reason or is it more of a factory safety thing. So, if I don't have the right charge, I'm going to have to disconnect the batteries and charge them one at a time with a regular 12v charger?

 

[Silvertip]

Re: 12v VS 24v operation

Tex -- point of clarification. That two-fuse thing you mention is definitely not for series-wired batteries. It does apply to a 12/24V system where both batteries are wired separately to the 12/24 plug using a three or four wire system. If the batteries are wired directly in series there is only one POS wire in the system. The jumper is sort of a POS wire but chances of it creating a problem are nil. One Ground, in any circuit should not be switched or fused. So -- series only 24V gets one fuse in the POS side. 12/24 gets one in each POS line between the batteries and the connector (this is not series wiring).

 

[Silvertip]

Re: 12v VS 24v operation

Basster -- That bow mounted 12/24 switch made the parallel (12V) to 24V series switch in the original boat configuration. In other words it performed exactly what you just did by connecting the batteries in series. That switch had absolutely nothing to do with safety. That switch can no longer perform its intended function. I just reviewed previous posts and I now need to ask how many wires you have coming out of your trolling motor. If you have three we need to talk some more -- and I believe we will.

 

[basster]

Re: 12v VS 24v operation

Thanks Upinsmoke, out of the trolling motor itself, I've got the attwood connector with 3 wires. I had 4 wires coming from the batteries to that bow mounted 12/24-off switch which then went to the bow "plug-in" with 3 wires. What I was going to do is get rid of everything and connect the 2 batteries in series with the jumper and run 2 wires to the "plug-in" and always run the TM on 24. and tape off the third wire on the TM and the "plug in"

 

[Texasmark]

Re: 12v VS 24v operation

Up. Mine is a Motorguide and is a 12/24. So I guess that's the reason for 2. Understand your comments about seriesing 2 12's for 24 which only needing one breaker.<br /><br />Mark

 

[Silvertip]

Re: 12v VS 24v operation

Basster - What you want to do will work. The third wire in the motor harness is always the tip off for a 12/24 motor. As you can see by your original wiring there are two ways to do 12/24, its just a matter of what type of connector panel the boat manufacturer installed and whether or not it had a 12/24 switch.

 

[basster]

Re: 12v VS 24v operation

What fuse do you guys think I should use, maybe a glass 30amp fuse or a 24v automotive breaker "shortstop"

 

[Silvertip]

Re: 12v VS 24v operation

Any department store that sells boating accessories has circuit breakers with a tab on them that connects directly to the battery. The other leg goes to the motor. They are less than 10 bucks. I prefer a breaker but others like a fuse. It really doesn't matter except the breaker makes a cleaner installation. 40 amp should be sufficient.