12v/24v power difference

[kyudizky]

boat i bought has a 12/24v '91 johnson trolling motor. when I got it, only one battery so it been running 12v. How much of a thust difference will there be adding a another battery and running in on 24v. trying to decide on whether to buy a new TM or not. If 24v will give me more power thats a much cheaper route.

trying to avoid buying another battery then having to get new TM, or buying a new TM when a second battery would suffice, and much cheaper.

also, how bad is it to run in salt water, if its not technically a saltwater TM?

Thanks!

 

[kyudizky]

Re: 12v/24v power difference

Anyone????

 

[EsoxRanger]

Re: 12v/24v power difference

I would assume the thrust would approximately double going from 12-24v. But it would be short lived, using a freshwater motor in salt is a bad idea. I would just invest in a new MinnKota, the maximizer technology will get you a lot longer battery life than that old dinosaur will.

 

[John Jones]

Re: 12v/24v power difference

You're not getting the full thrust if you're not running 24V through a 12/24 motor. That is, if you're motor is a 46# thrust, this is on high 24. High 12 may be giving you around 30# (it will be more than 1/2) I would buy the battery first, see what you think, and if you still need more, you will already be set for 24V. As the second part of the question, if you fish brackish waters, the trolling motor not designed for such will deteriate. John

 

[Silvertip]

Re: 12v/24v power difference

The 12/24 power difference may be significant or the same depending on how the motor is wound. 24 volts does not necessarily double the thrust and in fact it probably does not. What 24 volts does is increase the run time because of the efficiency of the 24 volts. If one looks at the amperage draw for 12 volt 55# motor for example, the current draw is about 50 amps. An 80#, 24 volt motor draws 56 amps. 45% more thrust but only about 11% more current draw.

 

[kyudizky]

Re: 12v/24v power difference

the motor has a switch to run on either 12 or 24. I may just buy the second battery, wire'em in a series and hope for the best.

By saying it will deteriate quicker in salt water, are you talkin about the motor or exterior pieces such as the motor housing and shaft? I do wash down and coat with rust inhibiter after every use.

Two other ignorant question, will either a MotorG or MinnK prop fit of my johnson or do i have to order a johnson prop?

My cranking battery is a Deep cycle, so I am going to buy a regular battery for cranking and move the deep cycle to get the 24V to the troller since the deep cycles are more expensive. Any special volt/amps size or type required for a outboard cranking battery (its a '84 Johnson V4 90HP).

Really appreciate the help!

 

[4JawChuck]

Re: 12v/24v power difference

I have a 812AP MK and a 865AP MK, the 865 is 12/24 capable and is basically the same unit (I got it for parts) and in 12V mode it is 42 pd thrust and in 24V its 48 pd...hardly worth the effort.