Hi,

my name is coen and i am from the netherlands.

I am building a remote controlled technic lego tank ( 100cm X 50cm X 35cm )

It has 4 tracks ( 4 X 150 pieces ) and runs on 8 XL motors.

the problem i have is that the motors need about 4 bat packs to work

good. this means a lot of weight, beacouse there are also about 20 other motors

and about 20 light's to power i have a serious problem.

I have looked on the internet for diverent thing's but didn't find a solution

for this power problem.

Does anybody have any sugestion's?

Greatings coen

Edited July 28, 201113 yr by coen

Well for the drive motors you could use 4 battery packs. And the other 2 motors can be attached to them if you just don't run them all at the same time. For the lights you could use an extra battery pack.

But is you're model that big or is it just brute force?

(foto's would be nice )

foto

i can't get the foto's on the forum??

Edited July 28, 201113 yr by coen

There is several different battery packs, but i would recommend using the rechargeable battery. It's the lightest of them all, but still cant deliver enough power for more than 2 XL and 2 M PF motors.

If you are willing to modify the electronic (not a purist) then i would recommend you use LiPo RC batteries at 7.4 Volts. These you can get up to at least 8 A/h from, and the best can deliver a peak current of more than 200 A.

You should also be aware that there is a limit for how much power a RC receiver can deliver. I think I've heard 1 XL and 2 M PF motors, but i can't be sure. Anyways it has an internal safety that will limit the current when it goes above the "safe area".

How come you need 20 M motor? Isn't it possible to multitask some of them through gearboxes?

-ED-

foto

i can't get the foto's on the forum??

Put the foto's on brickshelf, flicker or similar service, and add a deep link.

But the problem is that every motor needs to work exactly

and when you work with 4 battery packs just for the drive

it's not efficient, they dont get the exactly the same power.

Plus considering there is also going to be a turret that needs 3 battery packs,

al the other equipment, minimum of 6 other battery packs, this is to much weight.

isnt there a way to make some sort of electrical circuit that i can put on battery's

ore just an adapter?

becouse testing allone has cost me more than 60 battery's and i am only halve way done.

greatings coen

P.S. can anyone tel me why i dont get the picture's on the forum

What could you possibly be powering with 20 motors?!?!?

tim

Hahahahaha,

well...... let me see....

20 X light

left tracks: 4 XL motor's

right tracks: 4 XL motor's

side pods: 2 motor's

engine: 1 motor

pneumatic's system 3 motor's

master switch 3 motor's

Turret:

Rotation 4 motor's

horizontale position 3 motor's

shooting mechanisme 4 motor's

And what ever come's in mind, i dont care...........

i'm thinking about using 2 micro motor's but they are kind of hard to find them ( if you dont want to pay 35 euro for it )

remember that this model is 100X50X35 centimeters, so it is heavy.......

tonight i will try to put some foto's of it on the forum......

Edited July 28, 201113 yr by coen

Excuse me, but wouldn't it be alot more efficient to have 2 motors on each side for the treads?

Edited July 28, 201113 yr by airsoftg36c

You should also be aware that there is a limit for how much power a RC receiver can deliver. I think I've heard 1 XL and 2 M PF motors, but i can't be sure. Anyways it has an internal safety that will limit the current when it goes above the "safe area".

You could simply duplicate the receivers too.

I mean if you can duplicate the motors then you can duplicate the receivers. You will then simply end up with a whole bunch of independent circuits - battery box, receiver, motor, and that times 28. Well, not literally times 28, but you get the point. No need to connect the electrical circuit for driving, with that of rotating the turret.

All you need is a crapload of money - but given the size of the model you were needing that anyway so yeah

If two motors used to drive the same system, do not have the exact same speed, you can always add a differential. However I'm not sure if those are strong enough (particularly the 12t gears that go inside).

Edit: or use the RC motors (http://www.peeron.com/inv/parts/5292?img=21893). These are stronger, so you need less of them :) Of course they also draw more power and you need a conversion cable.

Edited July 28, 201113 yr by Erik Leppen

if i get the foto working you will see what i mean.....

there are 8 motors to drive this tank.

4 on each side

there is not realy a problem in connecting all the components to the recievers or anything like that,

i'm just wondering if there is a way to get rid of the battery packs. 9 battery packs ore more is just to much weight.

if i get the foto working you will see what i mean.....

there are 8 motors to drive this tank.

4 on each side

there is not realy a problem in connecting all the components to the recievers or anything like that,

i'm just wondering if there is a way to get rid of the battery packs. 9 battery packs ore more is just to much weight.

this is a bit of a crappy picture, next week i will show you more

Ahh, I see why you would need 4 motors per tread.. That looks very difficult. Good luck figuring it out!

Can't wait for the next set of pix!

Ahh, I see why you would need 4 motors per tread.. That looks very difficult. Good luck figuring it out!

Can't wait for the next set of pix!

Hahahahaha yes indeed, and i am caving my self in with problems.

i actualy have made a wire diagram just to figure out how i am going to connect everything.

my next shopping list........ don't even start...... hahahaha

it is getting ridiculous, but yeah....... it is just to much fun.

=

the pictures are not very good i wil take new one's next week

Holy shit! That's gonna be a massive tank! I sure hope it works out for ya!

Holy shit! That's gonna be a massive tank! I sure hope it works out for ya!

yeah it huge!

with the turret completted it wil have 4 working levels,

all scaled down to the size of a mini figure

yeah it huge!

with the turret completted it wil have 4 working levels,

all scaled down to the size of a mini figure

Is that a W-28 motorblock i see, or is it a star 6x7?

This is an insane MOC. Some of the most ambitious work I've ever seen.

I still think rechargeable batteries in individual closed circuits could solve both some of the weight problem, and the power problem. It will also be a lot cheaper for you in the long run, as you wont have to buy AA or AAA cells all the time.

How are you going to control this? It cant be all remote with that many motors?

-ED-

Edited July 28, 201113 yr by Nazgarot

Awesome work, Coen, absolutely gigantonomous!

You could solve your battery problem by using RC battery packs. About a year ago someone from the Netherlands (I don#t remember his name) modded an 8043 Excavator to use an 11.1V battery pack. Maybe someone here can bring up this thread? Those RC-batteries can deliver high currents of more than 10 Amps so three or four of them might be enough to power the whole tank. Remember that all Lego PF components, especially the receivers are made for 9V, so you are working out of specs and you don't get an Lego Purist approved model. But I haven't heard of any components that quit their job because of that overvolting.

Please share with us the progress of your tank, looks really appealing!

edit: Thank you so much, DLuders, this was the thread I was looking for. I wonder whether rien is still building LEGO, he hasn't showed up here recently.

Edited July 31, 201113 yr by grindinggears

Is that a W-28 motorblock i see, or is it a star 6x7?

This is an insane MOC. Some of the most ambitious work I've ever seen.

I still think rechargeable batteries in individual closed circuits could solve both some of the weight problem, and the power problem. It will also be a lot cheaper for you in the long run, as you wont have to buy AA or AAA cells all the time.

How are you going to control this? It cant be all remote with that many motors?

-ED-

Ed,

the motor you see is a rotating star ( 6X8 ) cillinder engine. de pistons rototate clockwise and the cilinders anti clockwise, look's pretty funny.

this is the goal:

there is 1 electric connection behind a cover. you hook that on a battery pack.

now you kan turn the system on, ( you only give power to the 3 motor's that will turn the battery packs inside the tank on).

these 3 motor's engage the other battery packs in the tank and the turret.

there are 2 systems that will always run: the star engine

the pneumatic system

the pneumatic system are two things: A 4 cilinder compressor with 2 airtanks ( 2 motor)

A 1 cilinder compressor (actualy just for show, but it works. 1 motor)

pressure valve. this control's the motor's by shutting them down

at 2.4 bar en turning them back on at 1.5 bar.

System's on a reciever:

driving driving ( 8 XL motor's ) 2 channels

the side pods (2 motor's) 1 channel

the turret horizontale position ( 3 motor's ) 1 channel

rotation (4 motor's) 1 channel

shooting (4 motor's) 1 channel

so i need 6 channels, 3 remote's........

but i have 4.......... so..........

any ideas???? hahahahaha

the rest of the component's will be controlled by switches on the tank

Edited July 28, 201113 yr by coen

hey

i was looking at other topics and i saw chrome cilinders.

does anybody knows where i can buy them?

Those RC-batteries can deliver high currents of more than 10 Amps so three or four of them might be enough to power the whole tank.

One should be ample. I regularly use 7.4 or 11V (2S or 3S) packs that will deliver 100A or more for other purposes. A small (2AH) pack that's rated to 20C or more is only about $30 and will deliver 40A (obviously, for 1/20 hours = 3 minutes). Depending on your design it may make more sense to use two or three 5AH batteries in different places around the model. The RC helicopter people use these batteries for their enormous power to weight ratio.

The other option would be a "12V" LiIon battery drill, which will be 3S/11V, and will have better battery life if you buy a half-decent one (500 cycles to 50% capacity rather than 200), and you get a free drill with every purchase :) The real advantage of drill batteries is that you get two batteries and a charger for a reasonable price, and if you don't wreck the contacts they will still power the drill.

11V is possibly a bit on the high side for the IR receiver but I don't know that for sure - I'm sure someone on the forums has played with that.

rien posted this Eurobricks topic about Lego "Power Functions on 11.1V" RC batteries. There is extensive discussion about the maximum voltage that PF components can handle. On this post, Out of Sight wrote these tips:

"Here are few notes to consider for everyone else BEFORE upgrading to 11.1v Lipo:

Make sure ALL the gears spins freely by giving some play/tolerances to their adjascent object. I did this during my assembly, the M motors seem happy, no apparent stresses when lifting the boom, the motors stay cool too. This will reduce friction by a lot, gives added agility and reduce battery consumption hence longer running time!

I'm also into radio operated electric car models, Lipos are mandatory in these high performance vehicle. By seeing previous posts,we need to understand the proper usage of Lipo:

1.The PF circuitry does not come with a low voltage cutoff LVC. The LVC is needed to protect the Lipo from over discharged below 3.0v/cell. In a 11.1v Lipo, the minimum LVC is 9.0v. You need to measure the voltage when running it on the PF or you'll damage the cells or puff the cells ultimately. Have you seen an exploding Lipo?? Very scary..it will melt the lego bricks since it mimicks a flame thrower.

2. 11.1v is the nominal voltage of a Lipo (1 cell = 3.4 volt). But a fully charged Lipo fresh off the charger is 4.2v/cell. So a 3 cell Lipo like Rien's is around 12.6v fully charged.

3. You need to buy not just any 3s Lipo, but those that are rated for the maximum current draw of the PF motors. A lipo that's operating above it's discharge rate will get hot, damaged and ultimately explode. Lipo usually comes in C rating. C stands for continuous curret. The maximum current is the capacity of the Lipo times the 'C'. Eg. 11.1v 3s 1500mah 10C, means the Lipo is able to supply 1500mah x 10 = 15000 mah. Or 15A. So this battery will be safe to use on the PF which draws around 2-5A under load."

Tank? I see a ship...

Oh man, this thing's gonna be huge !!

Woah....that's a massive project! I like that engine too. I'm looking forward to finished project.

That's a massive MOC!

I can't help thinking that you're wasting motors and adding unnecessary wieght by having 3 motors simply turning battery packs on. Cant you just have the switches on the boxes connected to a lever and axle system?

One should be ample. I regularly use 7.4 or 11V (2S or 3S) packs that will deliver 100A or more for other purposes. A small (2AH) pack that's rated to 20C or more is only about $30 and will deliver 40A (obviously, for 1/20 hours = 3 minutes).

I would use one 7.4 V LiPo pack. Light-weight and lots of amps, more than enough to power 20 lego motors.

In the experimental phase, I would not use an 11V pack because if a motor stalls (which can of course happen during experiments) then 11V will burn out the motor much faster than 7.4V (note: 7.4V is also enough to kill a motor if you stall it long enough, but I think some of the lego motors have thermal protection built in (to double-check, google: lego 9V motors compared)).

You can use more than the stated voltage limit provided that you don't let the motor produce too much torque (which translates into: too many amps).