boat electrics

[cranky]

so you decide to invest in a trolling motor...here a few thing to consider when wiring it up...

how do you determine the following:

the size trolling motor you require for the size boat you own?

the size battery and type of battery you need to power it?

the size of the wiring from the battery to the trolling motor especially if the battery is at the back and the trolling motor is in the front and your boat is 4-6 metres long?

what size fuse and where to install it to protect the wiring from catching on fire because thats what the fuse is there for?

type of joints required...do you just twist and tape or do you consider the load of the trolling motor and do the joints properly?

Do you run the electric cables and electronics cables together?

how many of you have ever checked the volt drop at the trolling motor when under load?

how many people know what a 30-40-54 or 70 lb trolling motor draws under load...i dont know of anyone who can answer this question...so how do they calculate the cable wire size and volt drop for you trolling motor....so you have to ask yourself how efficient is your trolling motor...was it sized...wired and installed correctly...and more importantly were the neccessary tests carried out to verfify the efficiency...min. volt drop at max current?

 

 

 

 

 

 

 

 

[MRA1001]

Hi Cranky,

I went through this process about a year ago. Here are some links and info as to how I choose the motor, battery and wiring gauge.

Start here: http://www.basspro.com/webapp/wcs/stores/servlet/CFPage?mode=article&objectID=29748&storeId=10151&catalogId=10001&langId=-1

how do you determine the following:

the size trolling motor you require for the size boat you own?
>> http://www.minnkotamotors.com/selectamotor/

the size battery and type of battery you need to power it?
>> I had a 12V 120AH Calcium battery that I used on my previous boat. [This is running on a 55lb Minn Kota Terrova. Lasts a whole day fishing comps (Rust de Winter, Rhenosterkop, ...)

the size of the wiring from the battery to the trolling motor especially if the battery is at the back and the trolling motor is in the front and your boat is 4-6 metres long?
>>Trolling motor to battery = Cable supplied with trolling motor
>>Outboard motor to Battery [Approx 4m) = 2 AWG Double walled flexible welding cable.

AWG Reference table: http://www.powerstream.com/Wire_Size.htm

what size fuse and where to install it to protect the wiring from catching on fire because thats what the fuse is there for?
>> 12V 60A fuse, available from car audio specialists

type of joints required...do you just twist and tape or do you consider the load of the trolling motor and do the joints properly?
>> All joints were crimped and then had heat shrink over the top

Do you run the electric cables and electronics cables together?
>> Power cables run on the Starboard side
>> Electronics on the port side
>> I am unsure if there will be any interference (and did not consider this whilst doing the installation)

how many of you have ever checked the volt drop at the trolling motor when under load?
>> I have not checked the voltage drop, should maybe do so!

I installed a Battery monitor so I could monitor:
* Battery voltage (V)
* Instantaneous current (A)
* Average current (AH)
* Battery capacity used (U)

This is very useful in understanding the consumption and ensuring that I do not damage the battery.

I hope this helps....

 

[cranky]

thanks for the info...

i noticed you have a monitor which can measure amps...would it be possible to take readings at different speeds and post them so we can get a better idea of the time period a battery will last if set to 1 or 3 or 5 for example...for a 55 lb x 12 volt trolling motor.

i have done some tests with a 36 lb hand control trolling motor out the water...but will do further tests while on the water at some stage.

 

 

 

 

 

 

[MRA1001]

Hi Cranky,

Was out at Rust-de-winter on Friday and took the following readings.

Current consumption on a Minncota 55LB Terrova Sneaker motor:

Speed Current Consumption (A)
1 0.3
2 0.9
3 2.4
4 4.9
5 9
6 15.1
7 21.5
8 28.2
9 35.5
10 41.3

Hope it helps.

 

[cranky]

thanks for taking the time to get this info.

 

 

 

[Fanie]

Cranky your questions are wide over a big range. You normally start out with the boat and then determine which trolling motor to use.

In most cases bigger is better, simply because there are places the big motor won't work and you can still use the trolling motor - if it's powerfull enough.

The newer trolling motors have continuous speed adjustment, and efficient motors drawing a lot less current than just a an electric motor. The props are also not just props, these were developped to either cut through weeds or simply un-knot themselves as to just a prop that will get stuck in about three turns.

Also keep in mind if you start the trolling motor will draw more current when the boat is not moving, then as the boat accellerates the current will become less, so a lot depends on the boat's hull form and how efficient it is in displacement mode.

Each person should also have an idea of how hard you fish the electric motor. Some okes can fish a week on one battery(s) while others it will probably make one day. So your fishing style also counts a lot.

Lastly some motors will feel right for you and you will dislike others. The price tag also plays a role, is it a simple tiller arm motor, a foot control or are you after the latest greatest remote controll fold up jobby that deploys itself and can even follow the depth contour of the water you fish in.

Whatever you're after, I still suggest the next size up and use the right type and size battery(s) and make sure you have the proper charging equipment to maintain the batteries.

 

[Fanie]

Btw, it is always a good idea to have a voltmeter installed to monitor the battery voltage. After a few uses you will get a good idea of how much is left in the batteries and depending on your situation can decide how to use it.

I can supply such meters if any one is interested, LCD voltmeter, and backlight for when it gets dark.

 

[cranky]

conclusion...there is a lot more to investing in a trolling motor...batteries and charger than most people think.

 

something to add...using a higher voltage trolling motor will also reduce the current draw...so if you plan on fishing comps which are longer than one day...using a new high tech energy efficient trolling motor at a higher voltage may be the way to go...but at the end of the day...money talks and it will depend on your budget...what can you afford.

 

 

 

[cranky]

conclusion...there is a lot more to investing in a trolling motor...batteries and charger than most people think.

 

something to add...using a higher voltage trolling motor will also reduce the current draw...so if you plan on fishing comps which are longer than one day...using a new high tech energy efficient trolling motor at a higher voltage may be the way to go...but at the end of the day...money talks and it will depend on your budget...what can you afford.

 

 

 

[navrik]

I fished Groenvlei yesterday - trolling motor only dam - and for the first time I realised I will have to invest in 2 x 12V deepcycles connected in parallel as 1 x 12V only lasted me from 06:00 till 14:30

I have a 41 lb 12V trolling motor on a 13ft boat.

 

[griff]

My two fish finders have voltage shown on the screen so one can keep an eye on voltage left.

On Groenvlei I use my small "Spyder 3" and always carry two RR1 batteries. Have never had to use both but when the wind picks up I "Get off of Dodge". Better safe than paddle.