Quick Breaker question

[yoster]

Hello,

I have a ranger boat - the trolling motor terminal has two 12v lines going to it. The trolling motor bridges them internally.

I know typically for a 24v trolling motor you get a 50amp or so breaker. Seeing as how the batteries are not in series in this configuration.. do I still need a 50-amp or would the correct amount be 25-amp per battery? Mentally I think, ok, just because they're not in series doesn't change the total current draw.. it's just 12v over two positive lines rather than 24v over one, but just wanted to make sure.

Thanks,
Matt

 

[Barnacle_Bill]

Re: Quick Breaker question

What size wire goes from the batteries to the trolling motor? You need to match the breaker size to that.

 

[dwparker99]

Re: Quick Breaker question

If you have a 24v TM, whether it has a 2 wire or 4 wire system, all the current the TM draws is flowing through each wire. If you stay with a 4 wire system, you need to put a breaker on each battery that corresponds with the wire gauge used.

 

[Silvertip]

Re: Quick Breaker question

You still have two batteries in series or you wouldn't have 24 volts. Once again, there are many ways to get 24 volts at the front of the boat. There are two, three and four wire systems. Technically, for a four wire system, you should have a 50 amp breaker within six inches of the postive terminal on EACH battery. The only reason you don't need two in a two wire system is the jumper between the two batteries is so short the chances of a problem are minimal. Breakers protect the wire, they don't protect the device.

 

[TerryMSU]

Re: Quick Breaker question

You still have two batteries in series or you wouldn't have 24 volts. Once again, there are many ways to get 24 volts at the front of the boat. There are two, three and four wire systems. Technically, for a four wire system, you should have a 50 amp breaker within six inches of the postive terminal on EACH battery. The only reason you don't need two in a two wire system is the jumper between the two batteries is so short the chances of a problem are minimal. Breakers protect the wire, they don't protect the device.

100% correct! Also, if you short a wire without a breaker on it, you will almost certainly get smoke and FLAME from the insulation. You may also have the battery literally explode. Neither of those is a good idea on a gas powered boat out on the water (or for that matter anywhere else.)

TerryMSU

 

[yoster]

Re: Quick Breaker question

Thanks guys - not really answers to my questions (wasn't asking how many I needed or if they're needed or how I'm getting 24 volts) - just needed to know the breaker size. But thanks! Silvertip more or less answered the question - sounds like I need two full 50-amps.

General note to bhile - I don't recommend running a breaker that matches line gauge in every situation. I personally upgrade my lines, running a breaker below that but still large enough to support the device is a safer method. Go too high on a breaker and you're almost eliminating the purpose of having one! If the lines and breaker are too beefy, it can hide a potential problem.