DIY Scooter Idea?

[mohave_steve]

I am looking at the Minn Kota Endura 30 for my first attempt. What do you recommend for throttle?

I have several ideas ranging from a simple magnetic on/off switch to a PWM speed controller fed by a 18 or 24v battery pack. I could get soft start, longer battery life and 35-38lb of thrust for short periods with the PWM controller. At the expense of a higher $ cost and complexity.

I have found a PWM controller that may work for about $30.

 

[Gary D.]

I am looking at the Minn Kota Endura 30 for my first attempt. What do you recommend for throttle?

I have several ideas ranging from a simple magnetic on/off switch to a PWM speed controller fed by a 18 or 24v battery pack. I could get soft start, longer battery life and 35-38lb of thrust for short periods with the PWM controller. At the expense of a higher $ cost and complexity.

I have found a PWM controller that may work for about $30.

OK, turn off the gray matter and quit over thinking this.

There is already a controller on the motor that was designed to be used with it already. You can use that same controller and just put a water tight shaft through the case.

Try looking at Motor Guide as well. Most of the time they are cheaper than Minn Kota and equal if not better in performance.

If you use one of those little bar switches you see above door for the alarm systems and a piece of vinyl tubing for the magnet it works very well. Mount the switch in the handle and then just squeeze the tubing towards the switch and it on. Lighten up and it’s off. You just need to add a relay to activate the solenoid which activates the motors. At least for the first one I'd stay with 12 volt. The batteries are available everywhere and are cheap.

I’ll take some pics of it this weekend. Think KISS.

Gary D.

 

[Gary D.]

Here are some pics:

Solonoid and relay. Battery is out.
ScubaBoard Gallery - DPV_F14-1 - Powered by PhotoPost

The speed switch. I used one here but one for each motor is best.
ScubaBoard Gallery - DPV_F14-3 - Powered by PhotoPost

Motor:
ScubaBoard Gallery - DPV_F14-4 - Powered by PhotoPost

Here is the magnetic switch:
ScubaBoard Gallery - DPV_F14-2 - Powered by PhotoPost

As a safety the magnet (vinyl hose) can be pulled off so the motors won't start.

Gary D.

 

[mohave_steve]

Gary,

thanks for the pics. Very kewl!

I understand that the Endura's come with a controller.

It is a resistor bank controller. By turning the controller you are switchting between different values of series resistance between the battery and motor. When you controll motor current by placing resistance in series you are wasting battery power by creating heat in the resistor bank.

Want better battery life? Use a PWM controller..... Want to go the furthest on one charge? Connect the motor directly to the battery and run it full speed...

Well the second statement does not take into account the additional drag created by trying to move faster through the water.

Perhaps I will start with the stock controller and look at more efficient options in the future.

I am leaning towards the single motor design. What are the advantages of the two motor?

Thanks

Steve

 

[Gary D.]

As long as the motor is more than a single speed it needs some type of controller. I'm PWM stupid so I just use the package as it came. I have run them direct but you still need the solenoid and relay unless you use a mega big switch.

I have found that with twin motors you get better speed and maneuverability. I have run a lot with the commercial units that have more thrust. Not only do I run faster and longer but when two divers get on the unit I still stay with the others with a single diver on it.

The other advantage is if a motor dies you still have one to come home on. I did have it happen once when I had a bad wire connection fail disabling one side.

I kind of look at it this way. A ship with a single screw is not all that maneuverable compared to a twin screw. A big fat bulky design is not as efficient speed wise as a sleek narrower design. I have built a couple of single motor units and don’t think I will build another one.

Gary D.

 

[jimdiverman]

As long as the motor is more than a single speed it needs some type of controller. I'm PWM stupid so I just use the package as it came. I have run them direct but you still need the solenoid and relay unless you use a mega big switch.

I have found that with twin motors you get better speed and maneuverability. I have run a lot with the commercial units that have more thrust. Not only do I run faster and longer but when two divers get on the unit I still stay with the others with a single diver on it.

The other advantage is if a motor dies you still have one to come home on. I did have it happen once when I had a bad wire connection fail disabling one side.

I kind of look at it this way. A ship with a single screw is not all that maneuverable compared to a twin screw. A big fat bulky design is not as efficient speed wise as a sleek narrower design. I have built a couple of single motor units and don’t think I will build another one.

Gary D.

Gary,

Is the limiting factor on depth the motor? And if so, are there motors out there to go deeper than 130'... say 200' or 300'.

A DPV is going to be one of my next areas of interest and pursuits, and if I invest in the time and expense to build my own, I will want to have a DPV that can cruise inside caves and deep wrecks. The electronics and home building don't scare me. I have a degree in EE.

Suggestions?

Thanks.

 

[Gary D.]

I don’t have a clue as to how deep they will go but I know a lot of the DIY dry subs use them to 200 and 300 feet.

I don’t know what the magnetic drive motors cost but to get them big enough for a DPV might cost more than a commercial unit’s retail cost.

If you want to play in caves I’d look at a Gavin and not a DIY unit. Ship wrecks is one thing, caves are another.

Gary D.

 

[Sh@rkW@tcher]

Gary, I have a question for you concerning your DIY DPV, how much does the twin motor unit weigh? You mentioned that you built a single motor unit earlier, about how much did it weigh?

 

[Gary D.]

Twin is 30.5# + 25# for the battery for a <56# total.

My big twin with 84# of thrust is 55# with another 50# for the batteries for roughly 105#. I'm rebuilding it now so it will be a bit heavier when it's done. Maybe another 5# is all.

If I remember right the single was only about 5# lighter or around 50#. The motors don't weigh that much it's the rest and the batteries that do.

Commercial units run in the same basic ranges.

Gary D.

 

[dumpsterDiver]

My buddy has built a few of them using trolling motors. He has had some difficulties. One of the problems is that you need to try to make the scooter just slightly negative, No body wants a floater and anything that is too negative underwater is a pain. Make sure that you design it to be a little bouyant and then you can always add a little lead on the inside or outside, but if you start with it too small (and negative), it is not an easily solvable problem.

I don't understand the elctronics or the controllers, but he was able to make a low and a high speed setting and active the switches with a magnet in the palm on the inside of the glove. When you grabbed the scooter in one spot it went slow and the other it went fast, When you dropped it, it shut off. Keeping the round, flat magnet inside the glove was not a problem at all. He kept a spare magnet on a little lanyard on the scooter itself.

I would want 40 or 50 lbs of thrust I think.