kms bismark

[chris fenertyParticipant @chrisfenerty25956]

hello everyone,

i have a major question concerning battery`s.

i need 12 volts and 5 volts, and i was considering using sealed led acid batteries, because LIPO`s have a bad reputation for blowing up.

if i need 12 volts for my motors, do i need a higher battery voltage, and how many A/hr would i need to have at least a hour worth of fun if not longer

[chris fenertyParticipant @chrisfenerty25956]

battery capacity and voltage

[ashley needhamParticipant @ashleyneedham69188]

Chris. Go for Nimh batteries, unless you HAVE an SLA ready to go. I only use Lipos when weight or size is an issue, ever had one blow up….with a bit of care they should not go that wrong. In addition they do not last as well as Nimhs. I might get two 6V batts and a series lead, If one pack goes, you can effectively replace just "half" of the 12v pack. It also gives you some 6v packs for other projects.

You will not be going fast with a battleship so the battery will likely last for hours. 4500mAhr size, oads of endurance.

The receiver is a handy source of 5v depend on the current drain. I have a few boats on which a spare rx channel powers led lights et.

Ashley

[Malcolm FraryParticipant @malcolmfrary95515]

The ESC will often have a BEC that eliminates he need for a separate supply for the radio itself and other items that plug into it.

As Ashley says, go for NiMH. A pair of 5 cell packs allows you to position them more easily than a Lead Acid lump. They are also much easier to look after than either SLA (need fairly constant attention to ensure long life) or Lithium which do have a charge cycle limit and very careful attention. Being lighter than SLA, you get to position the batteries where they are convenient to you. This allows you to position any ballast where you need it to be – preferably out at the ends to give a more realistic looking ride through waves.

What scale Bismark? I am assuming not a 1:350 one, since that size doesn't really lend itself to any SLA. Unless totally inappropriate motors are used, 4500mAH should give a very full afternoon's cruising.

[chris fenertyParticipant @chrisfenerty25956]

hello everyone,

my model boat is approximately 2.75 mtr long, the 12v is for 3 main motor drive, stepper motors for turrets and guns,

as well as radar

5v for sensors, control processors, lights, and rc reciever.

should i use 18v with a voltage regulator to produce 12v, there is heat loss due to voltage drop x current.

i was considering 24v but i have found a new source for 6v batteries.

i was going to monitor the voltage and bring up a alarm, so i knew when to bring it back in.

the sealed lead acid batteries i was going to use three for 18v and parallel another three to increase my a/hr

and use them for ballast at the same time.

what do you gentleman think of that idea

[ashley needhamParticipant @ashleyneedham69188]

It is a shame you did not appraise us with more particulars of the vessel initially as it is a tad larger than we were anticipating and suggestions so far run a bit short of the reality.

If the motors are 12v it seems pointless stepping down 18v to produce 12v especially as you have a source of presumably lead 6v batts.

How are you wiring the motors? Three esc…one for each, or are you going for a prop-steer arrangement? In any event the motors would be wired in parallel and not series so 12v is all you need. Run duration is dependant on the current consumed by the motors and the A/hr capacity of the batteries, and is usually a bit of a guesstimate in cases like this whereby there will be periods of manpower work, and loitering.

A voltage regulator could be used for the 5v supply.

Ashley

[Dave Cooper 6Participant @davecooper6]

Quite an ambitious project Chris.

I should look out for RC Swordfish torpedo attacks and rudders jamming !

Computer-controlled gunnery ? (There's a fascinating technical description of this on the internet. Sorry, couldn't find a suitable link for you just now).

I'm planning to use an "Arduino" for the turret on my RAF launch. In the 'C' program code you can select a random number generator and then get the chip's output pins to drive a stepper motor – fun to play with…

Good luck with the project,

Dave C

[Malcolm FraryParticipant @malcolmfrary95515]

For 12 volt motors, a 12 volt battery is the most efficient answer. A model that size could carry a much, much bigger battery than a 7AH one. A 1:96 Bismark, done as a full hull model rather than a shallow draft representation, will weigh about 112 pounds floating at waterline. Plenty of space for real, full size, car batteries if proper precautions regarding ventilation and acid proofing the battery compartment are made.

No point in using a higher voltage and regulating it down using a linear heat generator – UBEC regulators are available, but probably not easy to come by for the power levels needed. If odd items need higher voltages, circuits are available to step up voltage. Google for "step up voltage regulator".

A total of 15A needed for scale performance gives a theoretical 4 hours off a 70AH battery, probably a lot longer if cruising rather than escaping the attentions of the Home Fleet. A set of 3 of12v7AH batteries, one powering each ESC plus another to power the non-esc items, will work and give plenty of run time.

[chris fenertyParticipant @chrisfenerty25956]

hi everyone,

i intend to use a4988 micro stepper for control of a hollow shaft stepper motor for moving my main gun turrets and the six 100mm guns along the side (3 each side), as well as radar and targeting array.

i chose hollow shaft so i could use a actuator to raise and the guns azimuth, the a4988 requires minimum 12v for controlling output but 5v for control signals, each gun requires 5 optical sensors i case a lose the step count, so i need three sensors for turret position – hard left, center, hard right. two sensors for gun movement – fully lowered, fully raised. the stepper motor only requires 2 inputs – direction and step.

although the boat is long, it is narrow and the hull height is less than 200mm, so i do not think i can get a car battery inside it.

i was going to use some arduino mega pro or nano v3, i was going to couple a potentiometer to the rudders control, so when i deemed that i was going hard to port or starboard, i would reverse the appropriate motor so i could turn quicker, i also thought of choreographing the gun controls as the data flow using lora between the boat and me would be incredible but i am still interested in trying that out.

hence my question about needing a higher voltage and regulating it so the stepper controllers have 12v

[Colin BishopModerator @colinbishop34627]

The link referred to by Dave re using Arduino to control turrets etc. is here:

**LINK**

Colin

[Malcolm FraryParticipant @malcolmfrary95515]

i was going to use some arduino mega pro or nano v3, i was going to couple a potentiometer to the rudders control, so when i deemed that i was going hard to port or starboard, i would reverse the appropriate motor so i could turn quicker, i also thought of choreographing the gun controls as the data flow using lora between the boat and me would be incredible but i am still interested in trying that out.

Differential steering. Look for "Mixer". Either hardware in the boat between radio and ESC or done by the transmitter. Many transmitters do mixing. No point re-inventing something that is already on the market unless it is either going to work much better or cost a lot less, or both. Or do something extra that well established hardware cannot.

hence my question about needing a higher voltage and regulating it so the stepper controllers have 12v

5 volts will be needed, probably at very low current, for the control circuits. The control circuits will, if properly designed, be quite happy controlling any voltage. If a stepper motor control circuit requires the full motor voltage to provide the control signals, it comes down to a question of designing the right interface between the stepper control input and the arduino output.

 

Quick check of my car battery height – 175mm.  I didn't check the weight.

Edited By Malcolm Frary on 14/03/2021 09:40:05

[chris fenertyParticipant @chrisfenerty25956]

hi everyone,

i was going to use a4988 micro stepper units for my stepper motors and by selecting 1/8 or 1/16 step i would get smother movement, but it requires a minimum of 12v

i found a rc speed controller circuit on http://www.pt-boats.com, which i was going to use in conjunction with three motor gearbox units and reverse either side motor using a relay to pole change based on the position of the rudder using a pot and a arduino

so i am left with the question 12v high a/hr and put in a regulator for 5v or 18 v regulated down to 12v and 5v

[John W EParticipant @johnwe]

Hi there

When I built HMS Exeter, at 1:96 scale, I used the ACTion P94 speed controllers to control the 4 motors running on 6 volt. I was considering the Arduino system and also went so far as to how to programme and following instructions from the web about gun movements.

However, to me (and this is only my opinion mind) it was far too complicated and a waste of time as I could do exactly the same thing and have movements of the gun using a Futaba 8 channel control system running on 2.4. All I did was invest in 3 x 180 degree servos which are mounted under each gun turret and 3 mini servos which I mounted inside the gun turrets which in turn elevate and depress the barrels. The speed of which was governed by a unit by a Company called Forge. Basically Forge supplied the units which increase the movement of the 180 degrees turrets to roughly about 220 degrees. Also a unit to control the speed & slowed the servos down.

All I have done extra is made a Y lead up, so I connect 2 battery packs at 4.8 volt each up in series; which give me an extra bit of umph for the power supply for the servos and the rest of the electronics e.g. speed controllers & soforth. Just the way I did it, and, to me less complicated – because – I felt as though I was restricted by set movements of the Arduino system.

John

Edited By John W E on 14/03/2021 18:21:17

Edited By John W E on 14/03/2021 18:23:32

[chris fenertyParticipant @chrisfenerty25956]

hi there,

i see where you are coming from, but stepper controller only needs two wires, step and direction the stepper controller board allows me 1, 1/2, 1/4, 1/8, 1/16 of a step which slows it down as makes smooth motion, i will be setting the speed via a 3 way dip switch, which could also be done by outputs off a arduino, but it is a waste of outputs, the hollow shaft stepper 39mm square and approximately 25mm high and i was going to pass a actuator through the centre to control azimuth of the guns. and use optical sensors for max left, max right, centre, max azimuth, min azimuth

i was considering using lora to comunicate with the arduino`s, but decided on a 8 – 16 channel rc unit and do choreographed movements based on reciever inputs, because i need one servo for steering one for speed control, that leaves 6 inputs left which = 0 – 63 bits which is how many possible outputs you can have off the reciever.

does that make sense, cheap to make stepper controller because you can buy it already made very cheaply, i brought twenty units from banggood for about $30.00 nzd, i can go through my purchase list from aliexpress and banggod and let you know how much it cost

[Dave Cooper 6Participant @davecooper6]

Hi Chris

Just a few extra points on the Arduino front which may be useful :-

1. If the power supply side is getting messy, you can just use a PP9 battery as the 'chip' has it's own on-board voltage regulator.

2. You may find it easier to do a lot of the more complex control movements in the software. If you, or a friend, have any knowledge of the C++ language, it's mainly a question of calling the appropriate library and doing some tailoring.

3. I use the "Elegoo" R3 Uno starter kit for experimentation. It comes with a servo, stepper motor, jumper wires, breadboard etc etc. and is great for proving out theories before committing to the final solution.

4. If you need more inputs and outputs than the Arduino range can provide you can use the "Teensy" board instead. It will run the Arduino software ('Teensyduino&#39 so no need to re-program.

Have fun,

Dave C

[Malcolm FraryParticipant @malcolmfrary95515]

A link to a datasheet for the chosen circuit would be useful. A good data sheet can answer many questions, and might highlight some otherwise unforseen problems.

The few that I have seen for stepper controllers all indicate a need for cooling, either a heatsink or a fan or both. Stepper motors do have a reputation for speed and precision, but at the cost of being very thirsty for the work done, hence the need for cooling. Possibly the reason for the need for cooling. Not an issue with devices with external power (i'e; running of the mains) but definitely an issue in self powered portable equipment.

[chris fenertyParticipant @chrisfenerty25956]

hi everyone,

the a4988 stepper module comes with it`s own heatsink, and is capable of 2A per phase, i am not drawing that much.

i have already considered putting in a blower to keep the electronics cool

[chris fenertyParticipant @chrisfenerty25956]

Description:
39MM Hollow Shaft Stepper Motor 4 Phase 5 Wire Square 1.8 Degrees Stepper Motor
Specifications:

Length 39mm, height 22mm, output shaft length 13mm, output shaft diameter 8mm with a 6.15mm diameter hollow shaft

Step angle 1.8 degrees, resistance intermediate tap 54 ohms, both ends 108 ohms, cable length 140mm 5 wire.

12V Short circuit current = Intermediate Tap:0.2 A, Both Ends: 0.1A

Rated Voltage = 12vdc, Rated Current=0.05A, Rated Power = 5W, Weight = 60g
Note:
Motor is a two-phase six-wire stepper motor, but inside the wiring put two phases middle of tap connected to a second
terminal, so from the outside look, it is a four-phase five-wire stepper motor.
Connecting Tipes:
Pinout: A- Purple, A+ Red, B- Blue, B+ White, Brown and Black not connected.

[chris fenertyParticipant @chrisfenerty25956]

electronic speed control from http://www.pt-boat.com select general from the home page, select electrics, select speed controller, i used the circuit at the bottom of the page except i used three mosfets in parallel instead two as in the diagramn

[Malcolm FraryParticipant @malcolmfrary95515]

Finally found a datasheet for A4988.

https://www.pololu.com/file/0J450/a4988_DMOS_microstepping_driver_with_translator.pdf

Still having trouble seeing the need for an 18 volt supply, given that the A4988 uses a load supply voltage down to 8 from a max of 35, and the stepper that it is driving rates at 12volts.

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