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topwaterrob

24 To 36 Volt

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Im pretty sure it's been discussed on here prior, but I couldn't find it....  Can someone let me know what would need to be done to change my 24v system to 36 volts besides adding an extra battery....  I'm thinking of going to a much bigger TM if it's worth the effort...  Thanks

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You may need to increase the size of the wire from the battery to the TM. Thats not a MUST but it certainly wont hurt.

 

How big is your boat? I have a 55 on my little 17' aluminum and if its above 50 you better be ready when I step on it or youre going over the side.

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If you are thinking about it, you will need an extra battery tray, a third battery and some extra cables, use caution though, make dang sure the batteries are all the same,  using one smaller than the others or larger than the others can result in overheating.

 

Orient the batteries in the boat as such and wire as such.

 

1) set the first battery in

2) set the second battery in so that the negitve terminal is close to the positive terminal on the first battery

3) set the third battery in so that the positive terminal is close to the negitive terminal on battery two 

 

Wireing, 

1) run a cable from the negitive on the first battery to the positive on the second battery

2) run a cable from the negitive on the second battery to the positive on the third battery

3) the two remaining terminals will be the positive on your first battery and the negitive on your third battery,  use these two terminals as your connection for the 36 volt connection.

 

Read your owners manual for the 36 volt trolling motor, it will let you know what cable size is required in most cases,  if not you can e-mail the manufacturer and get all the answers you will need,  most of the time the cable size will need to match the plug in and you can use that as a guide,  if your original cables from the batteries to the trolling motor are too small or smaller than the plug in cable or power supply cable,  then you will need to up grade,  using too small of a cable from the batteries will overheat the cables when you are asking for a lot of power or a lot of amperage from the trolling motor.

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If you are thinking about it, you will need an extra battery tray, a third battery and some extra cables, use caution though, make dang sure the batteries are all the same,  using one smaller than the others or larger than the others can result in overheating.

 

Orient the batteries in the boat as such and wire as such.

 

1) set the first battery in

2) set the second battery in so that the negitve terminal is close to the positive terminal on the first battery

3) set the third battery in so that the positive terminal is close to the negitive terminal on battery two 

 

Wireing, 

1) run a cable from the negitive on the first battery to the positive on the second battery

2) run a cable from the negitive on the second battery to the positive on the third battery

3) the two remaining terminals will be the positive on your first battery and the negitive on your third battery,  use these two terminals as your connection for the 36 volt connection.

 

Read your owners manual for the 36 volt trolling motor, it will let you know what cable size is required in most cases,  if not you can e-mail the manufacturer and get all the answers you will need,  most of the time the cable size will need to match the plug in and you can use that as a guide,  if your original cables from the batteries to the trolling motor are too small or smaller than the plug in cable or power supply cable,  then you will need to up grade,  using too small of a cable from the batteries will overheat the cables when you are asking for a lot of power or a lot of amperage from the trolling motor.

perfect....  thanks  i already have a 71lb 24volt but i fish the slop and lake O alot which is hell on a trolling motor.....

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perfect....  thanks  i already have a 71lb 24volt but i fish the slop and lake O alot which is hell on a trolling motor.....

 

Your welcome, just keep in mind you are upping the available amperage by 1/3,  the 24volt system cabeling from the batteries to the trolling motor will need to handle the extra heat if you use the motor pretty hard,  just because you had a 71lb thrust motor before does not mean the cables from that system can handle the extra amperage the new trolling motor will be able to pull from the system,  use caution here and don't take it for granted.

 

Good luck and be safe !!!  

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My analitical part of the above post should be improved with a little more clearification,  Thank you my friend for your opinion and for bringing this to my attention.

 

A 36 volt motor will use roughly 1/3 the voltage needed at a max RPM of a 24 volt motor.

 

if you were to only run this motor no faster than what you ran the 24 volt motor your motor would consume less voltage from your source and the cable size would make no difference here.

 

However, if the 36 volt motor exceeds the RPM's of the 24 volt,  then the voltage may be restricted by the wire size,  resistance,  which equates to limited voltage available at the motor,  you may end up with the maximum available voltage that supplied the 24 volt motor as previous and not get the full benifit of what a 36 volt motor can offer,  in order for you to get the maximum available voltage needed to keep the motor humming,  I would suggest replacing the cable's if your wire size is 10 guage, if it is an 8 guage,  you are or may be at the limit of the 24 volt motor,  that size cable should be fine as long as the 36 volt motor does not spin faster than the 24 volt,  a 6 guage wire will help alleveate any resistance issues when we add in all the factors including length and would be the best suggestion.

 

One other question, do you know what amp breaker you have for your trolling motor currently? 

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Being new to the bass boat world I'm a little unsure myself what I'm dealing with and I too will be moving up to a 36v at some point. I have 6 gauge wire coming off of both batteries but I don't know where it goes from there. There is no jumper wire running from the pos. of batt. 1 to the neg of batt. 2. I have yet to find any breakers but I do have a fuse box in the cockpit. There is a fuse on the positive TM cable by the battery which leads me to believe the cables run all the way up to the TM plug. I haven't pulled the plug on the front yet to see if both cables are running up to it. The plug is the larger 3-prong style that twists and locks into place...Marinco I believe.

I'm assuming if I have 6 guage running all the way up I can forgo the extra wires when I upgrade and run jumpers between the 3 new batts.

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You assume correctly, and yes all you would need is the connection cables to the batteries to make it a 36 volt system,  most all breakers are found mounted somewhat close to the batteries,  it sounds like you either have a 12 volt system or someone has deleted the relay and installed a fuse.

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Somebody had confused the crap out of me with all that fancy voltage talk and voltage related to rpm stuff.

 

Increasing the voltage will reduce the current requirements for the same thrust.  The motor efficiency is going to be greatly increased so it will run longer on the same thrust.  If you're wire size has been good for a 71 pound 24v motor, it will be just fine for a 101 pound, 36V.  I don't have the figures or done the math but I seriously doubt there is very little difference in the current draw between the two motors. 

 

It has be a while since I looked them up and I'm sure someone with come back with the right numbers just to say I'm wrong, but I think it's something like this:

A 12 volt motor using 1.5 amps per pound of thrust

A 24 volt motor using 0.9 amps per pound of thrust

A 36 volt motor using 0.6 amps per pound of thrust

Like I said, I'm sure these are not the exact numbers but this is very similar to what the results would be when you upgrade.

 

As for the batteries, yes, they must all be the same make, size and age, or you will be having dead battery problems until you do finally replace all three.

 

A common practice, though I don't recommend it, is to use one as the cranking battery.  That way you still only have to have three batteries but if you happen to run them down with the TM, you're screwed because the big motor is not cranking.

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[quote name="Nitrofreak" post="1245183" timestamp="1361907970"

One other question, do you know what amp breaker you have for your trolling motor currently? [/quot

Nitro I was following for a while but now you're starting to talk circles around me here. If I understand your saying that to be safe if I upgrade, I should rewire using heavier gauge as to prevent heat issues. That being said, I don't how to check what amp breaker I currently have and or if I would need to.change it as well. Thanks again

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This is a Minn Kota 60 amp breaker. It is made for trolling motors. Follow your existing TM wires to look for something like this or a fuse panel or SOMETHING to interrupt the current flow if you have a problem. If you don't have one, get one. It is worth the trouble.

bdrsjn.jpg

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Specifications for Minn Kota freshwater Engine Mount Motors:

Model Motor Configuration Maximum Thrust Volts/Max. Amp Draw Recommended

Boat Length MSRP

MK202/EM Dual 202 36/98 22' – 26' $1,449.99

MK160/EM Dual 160 24/116 20' – 24' $949.99

MK101/EM Single 101 36/49 18' – 22' $849.99

MK80/EM Single 80 24/58 16' – 20' $749.99

MK55/EM

Single 55 12/50 14' - 18' $549.99

Hard to read but 101 lb. thrust amp draw is 49 amps

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Like I said, if you are already running a 71 pound 24 volt and if you go to a 101, 36 volt, the only thing you will need to do is add the upgrade your battery system. Three new, like batteries and the additional interconnect cables.

The current draw for the 71, 24V is going to be very close to the current draw of a 101, 36 volt.

If you happen to only be running a 50 amp breaker, I would also recommend upgrading to a 60 amp. A 50 amp will even cause problems with the 71 pound as the batteries age or start getting weak.

BUSSMAN makes the circuit breaker shown above and you can buy them at some auto parts stores. It's been three years since I bought one but my last one was $45 at the Bumper to Bumper warehouse I get my parts. http://www.ebay.com/itm/Bussman-60-Amp-Circuit-Breaker-Waterproof-184060-/180531043810

Here's one on ebay cheap

Understand, current draw is what determines cable size requirement, not voltage. Your current draw is not going to change enough to amount to anything.

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Like I said, if you are already running a 71 pound 24 volt and if you go to a 101, 36 volt, the only thing you will need to do is add the upgrade your battery system. Three new, like batteries and the additional interconnect cables.

The current draw for the 71, 24V is going to be very close to the current draw of a 101, 36 volt.

If you happen to only be running a 50 amp breaker, I would also recommend upgrading to a 60 amp. A 50 amp will even cause problems with the 71 pound as the batteries age or start getting weak.

BUSSMAN makes the circuit breaker shown above and you can buy them at some auto parts stores. It's been three years since I bought one but my last one was $45 at the Bumper to Bumper warehouse I get my parts. http://www.ebay.com/itm/Bussman-60-Amp-Circuit-Breaker-Waterproof-184060-/180531043810

Here's one on ebay cheap

.

Thanks very much for great info ...

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Somebody had confused the crap out of me with all that fancy voltage talk and voltage related to rpm stuff.

 

Increasing the voltage will reduce the current requirements for the same thrust.  The motor efficiency is going to be greatly increased so it will run longer on the same thrust.  If you're wire size has been good for a 71 pound 24v motor, it will be just fine for a 101 pound, 36V.  I don't have the figures or done the math but I seriously doubt there is very little difference in the current draw between the two motors. 

 

It has be a while since I looked them up and I'm sure someone with come back with the right numbers just to say I'm wrong, but I think it's something like this:

A 12 volt motor using 1.5 amps per pound of thrust

A 24 volt motor using 0.9 amps per pound of thrust

A 36 volt motor using 0.6 amps per pound of thrust

Like I said, I'm sure these are not the exact numbers but this is very similar to what the results would be when you upgrade.

 

As for the batteries, yes, they must all be the same make, size and age, or you will be having dead battery problems until you do finally replace all three.

 

A common practice, though I don't recommend it, is to use one as the cranking battery.  That way you still only have to have three batteries but if you happen to run them down with the TM, you're screwed because the big motor is not cranking.

 

Basic electronics, if a motor is able to turn or create more rpm's it will require more current to do so, tempratures also plays a determining factor in how much amperage a motor will consume,   and a less restricted circut to handle the amount of electrons flowing through a circut, ie the wire size and length for example, plays an important roll as well,  if his current motor and his new motor vary grately than this may be an issue,  the propellers pitch has a significant effect on the required motor power,  dependant upon pitch,  as a prop rotates faster and faster,  it is stalling more and more,  this induces resistance,  which in short takes power delivered by the motor,  perminant magnet motors DC are characterized by it's locked rotor torque or referred to as stall and it's no load angular velocity or speed,  the speed of a DC motor is directly proportional to it's armature voltage,  so RPM's are a determining factor in my opinion,  I do not know what motor he has,  I can only assume,  but I feel if I did not mention the fact then he may never be aware that this could be a determining factor,  if it should only vary slightly then there should be no issue or a very limited one.

 

Current is the rate at which electrons flow in an electrical circut,  the rate at which they flow is an amp or ampere,  voltage is the pressure that allows electrons to flow,  we both know how electricity works. 

 

All I suggested was that he check his wire size, if it was too small he should upgrade,  if the wire size was at least an 8 guage cable, he may or may not need to change anything,  there should be a listing on the box or packaging as to the available RPM range this motor is possible of generating, you will not get the maximum RPM from the 36 volt system or any system for that matter if there is too much resistance, and it warrants a look to make sure the wire size is correct and as close to resistance free as possible to handle the load placed upon it.

 

I have seen butcher shops half a## repair circuts,  and they may be fine for a given circut,  we can upgrade to something like a 36 volt circut and be just fine at low loads, but the OP stated he fishes in slop and that it is he## on a motor,  what happens to a motor when it gets its blades clogged with slop,  it has to work harder, when a motor has to work harder it requires more amperage more amperage equals more heat, more heat equals a melt down of either a componant or a circut, which one comes first, usually the circut in most cases,  and if a circut has been altered,  it very well may not be safe or suited for this system.

 

If a circut has too much resistance you will not acheive the RPM's the motor is rated to produce.

 

My apologies for confusing everyone.

 

 

[quote name="Nitrofreak" post="1245183" timestamp="1361907970"

One other question, do you know what amp breaker you have for your trolling motor currently? [/quot

Nitro I was following for a while but now you're starting to talk circles around me here. If I understand your saying that to be safe if I upgrade, I should rewire using heavier gauge as to prevent heat issues. That being said, I don't how to check what amp breaker I currently have and or if I would need to.change it as well. Thanks again

 

I am only asking that you check your wire size, if you have an 8 guage wire you should be fine, but don't under estimate the circut, make sure of it's integrity and that it's resistance is very low, upgrading to a 6 guage will allow for extra current flow and will provide even less resistance should you choose to do so,  it is mearly a suggestion. 

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I guess I missed a lot of what you are saying while I was getting my degree in electronics, which I happen to have. Some of what you are saying is so, but then you start mixing things with personal thoughts that make no since.

He has not said what year model and type boat but six gauge cable has pretty much been the standard for year of any size, some have even installed four gauge. However, I won't disagree that it wouldn't hurt to verify he has at least six gauge, but when you say 8 gauge would be "fine", that's totally wrong. He would have way too much voltage drop with that small of wire, even with the motor he has now. 8 gauge wire will not handle 50 or so amps through approximately a 50 foot circuit, which is close to what would be in the boat (you do understand it's the total length from the battery to the motor and back to the battery). 6 gauge is the minimum and four gauge would be even better, but I would not spend the funds to upgrade to four if I already have six gauge, you would probably only see a one volt or so increase in motor voltage.

I still don't know what you are talking about when referring to the RPM being the determining factor? Load is the determining factor. As for the additional load the 36 volt motor placing on the circuit, again not so. As you increase the voltage, the motor becomes more efficient. If you compare a 36 volt and 24 volt motor of the same torque, the 36 volt motor will use considerably less current.

Anyway, we don't need to hijack this post discussing electronics.

The motor he has and if he's upgrading to a 101, 36 volt, both will have approx the same current demands and both will need at least six gauge battery/marine cable, for which most likely he has if he's dealing with any boat of size made in the past 20 years.

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It is certainly not my intention to upset anyone here or try to insult anyones intelligence,  I can see I am having issues in trying to get my point across,  and that is no ones fault but my own,  my apologies.

 

Maybe this will help maybe it won't but if you want to figure out the amount of ampere draw from a trolling motor.

 

lb thrust divided by motor voltage times 12 will equal the ampere draw

 

101/36 = 2.80 x 12 = 33.66 amps        71/24 = 2.95 x 12 = 35.49 amps

 

To figure out the time you can run at full load divide the batteries amp hour rating for instance 105 and the ampere draw from the trolling motor which was 33.66 for the 101 and 35.49 for the 71.

 

105/33.66 = 3.12 hours

 

105/35.49 = 2.95 hours

 

I hope that helps to understand the little bit of difference between the two.

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Again, not sure where you are getting your info for the math but that's not right.  As one has already posted from MinnKota, their 101/36 Volt draws 49 amps.  Logic should tell you that a 71/24 is going to draw a lot more than 35 amps and a 101/36 is going to draw a lot more than 33 amps.    However, even when you do your math, it still shows you there is very little difference in current draw between the two motors so if he has been running fine with his current motor, there's going to be little difference with a 36 volt, other than possibley less current draw.

 

Also, you can not do a direct calculation on runtime using the manufactors 20 hour rating on any battery.  That is done with an extremely low current draw of 5 to 6 amps and when you increase the amp load, the battery Ah rating drops a lot.  At a full load of 49 amps a 105 Amp hour battery is only going to be about a 65 amp hour so the run time would be more like one hour and a few minutes. 

 

It's apparent you know something about what you are trying to get across, but there's several areas you are missing the boat.

 

Anyway, this is my last response so you can post what you like, I just hate seeing bad info being given.

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I too will make this my last post on this subject, but first and foremost I wish to offer my sincerest apologies to the OP and BR for getting way off topic here.

 

I took the liberty to re-read the thread, I can see clearly that I was simply just not making sense, and most likly should have just stepped back for a little until I was better prepared to offer the right opinions and advice.

 

Electronics are a funny little thing in my opinion,  it seems to be one of the only big things in life,  besides life itself,  that has what we refer to as "variables" and a lot of them,  the theory of electricity is something that has been openly discussed and argued for centuries,  while certain facts remain a stable post in the evolution since the discovery of electricity.

 

To the OP,  my suggestion of using an 8 guage wire was absolutely incorrect,  however I remain adamant in the fact that you should check the manufactures suggestions on the usage of the recommened cable size for the motor you are purchacing,  my sincerest apologies for the confusion there,  you should always take the manufacturers recomendations under strong consideration otherwise you may end up with a voided warranty,  or worse yet something major could happen and damage the boat or you yourself could be put in danger.

 

As for other things, 

 

I do not feel I have posted anything "bad" other than the fact that I was misleading in the cable size,  bad info,  no,  confusing info,  to say the least for sure.

 

I won't make excuses for my reasoning,  but to say it was "bad info"  I would have to disagree,  the argument could be made in many ways here.

 

Fact is when we look at posts both are at fault here, 

 

 

A common practice, though I don't recommend it, is to use one as the cranking battery.  That way you still only have to have three batteries but if you happen to run them down with the TM, you're screwed because the big motor is not cranking.

 

 

As far as "bad info",  in your post above,  you stated you would not recommend using the battery configuration in this manner,  but yet you laid the plan for how it could be completed,  does that not suggest that it could be used in this manner?  why would you eplain how to do it if you would not suggest it?

 

Never ever would I even remotly suggest that the owner leave him or herself at risk by doing such a thing as using their primary source of dependency for modes of mobility up to chance,  had there been an alternitive suggestion following the comment allowing the user a more viable alternitive for charging the batteries and or lessen the cost of having to purchace a third battery,  then I would not give it a second thought.

 

One more thing I noticed in that comment made,  you politely mentioned you had a degree in electronics,  now,  unless I missed something my classes,  a "big motor" is using electricity to make power or provide a means of propulsion in this case,  assuming this boat is not a hybrid,  I am guessing it has an internal combustion engine,  if you are as adamant about "bad info" as you state you are,  then I would assume that correctly addressing what a device is used for has to have some kind of priority.

 

As for my math,  as stated earlier, there are always variables in the field of electronics,  the equasion is a direct result from formulas used for many years,  the 101 that was used as an example in a previous post utilised a maximum ampere draw of 49 amps (recommended) not actual,  as for the run time lots of good information there that you put in your post,  but then again,  it is still dependant upon variables,  it was put there for the OP to have a general idea of what he or she can expect to see,  not as an absolute, I did not make that clear in my post.

 

I am just as much at fault here,  I want to be perfectly clear,  I have already offered my apologies.

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Thanks for all of the replies, the discussions were / are very intriguing.  I ended up staying in the 24 volt range but got the 80lb Minn Kota Maxxum.  I figured i saved several hundred with not having to buy new batteries and a 3 bank charger, weight etc....  thanks again....

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