12v Conversion to 24V. How do I know if cables are rated for 24V?

[MidCoast]

I currently have a 12V system for my trolling motor on my fishing boat. I want to purchase a 24V trolling motor and need to do the 24v conversion. Can I use the same cables that's already at the bow for 24V? How would I know if they're not rated for 24v?

If current cables at the bow are not rated for 24V it must be difficult to put in new cables for the conversion?

[acroman]

No need to change the plug-in just need one more cable to run the batteries in a series. search series vs parallel and will give you the info you need.

[Brad B]

most modern day boats will run a 6 gauge wire for the trolling motor. this is more then enough for 12 or 24 volts. check your wire and see what gauge it is. you would only have issues if the wire gauge (diameter) is to small.

[fishwater]

The higher voltage means less current to achieve the same output power, so if it works for 12v it'll work for 24v.

[delcecchi]

No need to change the plug-in just need one more cable to run the batteries in a series. search series vs parallel and will give you the info you need.

Best way to hook batteries in series is with a short jumper between batteries right in the compartment. I don't think anyone makes old school 12/24 trolling motors any more.

[snagger]

What guage should that short jumper cable be? My jumper needs to be replaced and i'm wondering if it's too small because there is some melting of the plastic.

[Hoey]

I believe wires are rated for amps. Many available on the internet. I suggest getting a battery to battery jumper of the same gauge or larger than the boat wiring. These are available with factory terminals from many shops.

[aanderud]

The higher voltage means less current to achieve the same output power, so if it works for 12v it'll work for 24v.

That's a pretty broad statement. I agree that when going from 12 o 24, the same motor would draw 1/2 the current to achieve the same output power. So yes, the same exact motor he had on there would work on the existing wires if it could operate at 24 volts, because the current would be cut in half.

That doesn't mean the new motor will be fine. The new motor might very well have a much higher thrust/power, and thus might actually draw MORE current (even at 24 volts) than the old motor drew at 12 volts.

[fishwater]

That's a pretty broad statement. I agree that when going from 12 o 24, the same motor would draw 1/2 the current to achieve the same output power. So yes, the same exact motor he had on there would work on the existing wires if it could operate at 24 volts, because the current would be cut in half.

That doesn't mean the new motor will be fine. The new motor might very well have a much higher thrust/power, and thus might actually draw MORE current (even at 24 volts) than the old motor drew at 12 volts.

Yeah, I forgot about all those imaginary high power motors.

[aanderud]

Yeah, I forgot about all those imaginary high power motors.

Wow that's quite intuitive. Imaginary? My boat (a 1997 crestliner) was wired with 8 gauge wire from rear to front (around 18-20 feet of cable, total length battery to plug up front), which was probably enough for a small 12 volt 36 or 45 lb thrust motor on front.

When I upgraded to 80 lbs 24 volt motor, the manual says the max current draw was over 50 amps (around 56 if I'm remembering correctly), and they recommend installation of a 60 amp breaker in addition to proper gauge wire. So yeah, there are higher powered motors, they're not imaginary. And these non-imaginary higher powered motors do take thicker gauge wire to supply the current needed for that power. Not sure why you're getting so snarky, I'm just trying to add value to the thread here.

[fishwater]

So, it sounds like your boat was wired inadequately to begin with, not really that the new motor required a significantly higher current draw. The current draw in your example of going from 36lb or 45lb 12 volt to 80lb 24 volt is approximately identical. You'd need an imaginary 24volt high power motor to draw a fractionally greater current.

[delcecchi]

I believe wires are rated for amps. Many available on the internet. I suggest getting a battery to battery jumper of the same gauge or larger than the boat wiring. These are available with factory terminals from many shops.

I didn't know that such jumpers were sold. That sounds like a really good idea. If a guy was to make his own, I would go with either 8 or 10 gauge. Anything bigger is overkill. Good terminals are important.

[jmd1]

make the wire size the same for positive and negative. you flow the same about from the batteries to the device and then return the same amps/volts back to be recharged. If you too small of wire you will end up melting wire, too large does not get used the way it should. you need to figure our the current amp draw and wire according.

[aanderud]

So, it sounds like your boat was wired inadequately to begin with, not really that the new motor required a significantly higher current draw. The current draw in your example of going from 36lb or 45lb 12 volt to 80lb 24 volt is approximately identical. You'd need an imaginary 24volt high power motor to draw a fractionally greater current.

A 36 lb motor very well might draw somewhere in the 30-40 amp range, which I would say IS significantly less than my new 56 amp requirement. I guess your definition of 'significant' may be different though. I don't own a 12 volt motor that puts out 36 lbs of thrust but I have an inkling that they don't draw anywhere NEAR 56 amps.

Boats have not always been pre-wired with 6 gauge wire, and I was basically just giving an example that backs up what Brad B alluded to above that most MODERN boats are equipped correctly, but that in the end the gauge is what matters.

Your broad statement that "if it worked for 12, it will work for 24" is certainly not always accurate, especially since you have no idea what the 12 volt motor or 24 volt motor in question draw amperage-wise, or what the wire size is. You're probably correct MOST of the time, but then again fires are started when people start assuming things. You're still trying to argue for the sake of arguing, and I'm not sure why. I guess you can't stand being wrong. Oh well, since it's the internet, I've come to expect that there's going to be plenty of inaccurate information out there.

[aanderud]

I didn't know that such jumpers were sold. That sounds like a really good idea. If a guy was to make his own, I would go with either 8 or 10 gauge. Anything bigger is overkill. Good terminals are important.

+1 on using good terminal connections on the wire.

I just used the same 6 gauge that I was wiring in the length of the boat, since I had some on hand and only needed a couple feet. But, you're right that it wouldn't need to be that heavy considering the short distance involved in jumpering the battery.