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Offline rockchuck

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TCB in KingTiger
« on: April 01, 2018, 10:50:01 PM »
Hi tankers
I finally finished the install on the Kingtiger. This has a Torro metal hull and running gear and metal tracks. It has a HengLong upper hull with a BB turret but I have parts to build another turret which will be IR so I can swap between the two.
This means I will have the upper hull wiring setup to use either the BB/IR option so should just be plug and play.

So what about the driving test with the TCB and a Taigen sound board.
Fantastic is the word to use. The low speed control is unbelievable. Slow turns etc look very life like. I am yet to play around with the different drive settings- some of these you can setup on your radio to swap between so I will do that as it makes it easier to see the difference when driving.

The only issue I have is with the turret rotation. I have this connected to motor port A and when I turn the turret I noticed that the TCB will shut down.  I can still move the turret but I have to restart the engine to get the sounds back, I haven't got the shut off timed function activated so I think because the turret is very large and the motor is drawing perhaps excess current to drive it (I think some wiring maybe in the way and the BB unit hits them and then pushes thru needing more current)  and this robs the tcb of power and causes the shut down.
I will do some more tests -- the airsoft unit does protrude into the lower hull a long way especially if you have the barrel fully elevated-- when I get the IR turret working this won't have that problem so we shall see.
I am going to buy the turret ring (metal) that has the ball-bearings on it as this will help the reduce the turning force required so may fix the problem.

The wiring took a while to work out. I ended up installing a larger capacity main switch and have fused the motor feeds with a 25amp fuse and fused the TCB with a 5 amp fuse.

Anyhow the Tcb is great -- you have a very good control over all the functions and you can customize for each tank-- well done Luke and co. Now to get started on the others.

cheers
rockchuck


IMAG0121.jpg
TCB in KingTiger IMAG0121.jpg
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Offline LukeZ

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Re: TCB in KingTiger
« Reply #1 on: April 02, 2018, 03:45:27 PM »
The only issue I have is with the turret rotation. I have this connected to motor port A and when I turn the turret I noticed that the TCB will shut down.  I can still move the turret but I have to restart the engine to get the sounds back, I haven't got the shut off timed function activated so I think because the turret is very large and the motor is drawing perhaps excess current to drive it (I think some wiring maybe in the way and the BB unit hits them and then pushes thru needing more current)  and this robs the tcb of power and causes the shut down.
I will do some more tests -- the airsoft unit does protrude into the lower hull a long way especially if you have the barrel fully elevated-- when I get the IR turret working this won't have that problem so we shall see.
I am going to buy the turret ring (metal) that has the ball-bearings on it as this will help the reduce the turning force required so may fix the problem.

Hi Rock, it's possible you have an over-current draw situation but it seems unlikely. First you say the "TCB will shut down" but then what you describe sounds more like the TCB remains operational - if you can keep moving the turret then it hasn't drawn too much current, and also it means the TCB is still running.

I'd double check to make sure you don't have a function assigned to the turret stick to toggle the engine, there is one included by default which you may be triggering when you move the turret stick. Check also to make sure the turret isn't jiggling some wire as it traverses.

Of course if you have an amp-meter you can try to take a measurement and that would be worthwhile to do. Other troubleshooting tips include viewing the TCB output in Snoop mode in OP Config to see if it tells you anything or seeing if the issue still happens if you remove the turret.

Otherwise I'm glad you're enjoying things. You have done a very meticulous job on the wiring I can see, you are no doubt a detail person!
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Offline johnnyvd

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Re: TCB in KingTiger
« Reply #2 on: April 03, 2018, 04:44:23 PM »
Hi Chuck, this looks great! This week my Torro King Tiger will arrive and receive the Openpanzer makeover also..

Just one question: what is the speaker you are using?
* E-75 / E-100 PAK44 "monster" - in progress
* Sturmjagdtiger PAK44 - in progress
* pz.kpfw KV-2 754(r) - in progress
* T-34 88mm "Kurland Tiger" - in progress

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Offline rockchuck

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Re: TCB in KingTiger
« Reply #3 on: April 03, 2018, 08:24:48 PM »
Hi Johnny

the speaker is 50mm size and is rated at 10 watts 8 ohm. see link for detailshttps://www.jaycar.com.au/shielded-2-10w-8-ohm-full-range-speaker/p/AS3032

I had to use this size because I had limited room for anything bigger like a Visaton- this is because the airsoft unit protrudes into the lower hull and requires a lot of space to clear the unit when you rotate the turret around.

These speakers are cheap compared to the Visaton but the sensitivity on them is only 78dB as compared to Visaton frs7 which is 88dB. So that's 10db which is a lot --so what that means is at a 1 watt input to the speaker it will produce 78db of sound pressure level (spl) loudness whereas the frs7 being 10db more sensitive will only require one tenth of a watt -- 0.1watt to be as loud as the Jaycar speaker so for a given size amplifier the more sensitive speaker will always sound louder.  This has nothing to do the what the speaker is rated at in power handling watts. It always good policy to get the right rating to match your amp.

Mounting the TCB in the Torro KT hull is a bit limited. The TCB will fit across the hull ok but the problem is the connections on the end of the TCB ie-- the RC and radio connectors-- by the time you plug these in you have increased the length of the TCB by some 30% and it won't fit across the hull. I toyed with the idea of desoldering the rc connectors and replacing them with upright pins and doing the same for the radio connector although that would be a bit more difficult to do -- you would have to bend the pins up somehow.

It does work ok with how I have done it but means using the smaller speaker. If you look at my pic at the batteries you will some some foam installed to stop them from moving -- this would give you enough space to fit the Open Panzar sound card. This is another reason why I choose the small speaker as I intend to make these sound boards soon.

I mounted the ESCs for the motors so they could access the open vents in the upper hull for cooling. The aluminium  L bracket holding the switches is a loose fit over the plastic boss for the rear hull plate so you don't have to drill holes in your tank. I then use some foam as a washer to take up the slack so it didn't move around and rattle.

Good luck with your build and don't forget to post some pics.

cheers
rockchuck

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Offline Outofmydepth

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Re: TCB in KingTiger
« Reply #4 on: April 11, 2018, 05:11:06 AM »
Hi Rockchuck,

That is a wonderful installation in what is a cramped space - it has inspired me to try and be as tidy! I note you have used two separate esc's - did you consider using one (serial card at all?). Cheers Chris.

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Offline rockchuck

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Re: TCB in KingTiger
« Reply #5 on: April 12, 2018, 09:18:45 PM »
Hi Chris
yes I did look at the SabreTooth controllers but they are very expensive and although the overall footprint size is smaller than the two X45 esc next to each other it was still difficult to find enough space to fit the Sabretooth. With the X45 esc they are quite small and so can be located anywhere around the tank to take use of smaller spaces, it just makes the wiring a bit more messy. Also the X45 esc are very cheap.

One thing I not sure about is how much current the gearbox motors can take. They have no rating on them and so with the X45 being able to deliver 45amps you could be in a stall situation or uphill etc and burn the motors out. That is why I fused the ESC's with a 25 amp fuse.

cheers
rockchuck

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Offline jhamm

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Re: TCB in KingTiger
« Reply #6 on: April 13, 2018, 12:38:54 AM »

One thing I not sure about is how much current the gearbox motors can take. They have no rating on them and so with the X45 being able to deliver 45amps you could be in a stall situation or uphill etc and burn the motors out. That is why I fused the ESC's with a 25 amp fuse.


Hi,
i build a KingTiger for my Son.... weight arround 8 kg.
A spinturn on grass pulls the most current.
With standard Gearboxes and Motors the tank pull in sum (mesured) up to 15 Ampere.
This is arround 7.5 A stall current each Motor and thus corresponds to the specifications.
I think the ESC is not the Problem, they only need free Airflow for cooling.
To really protect the Motors put a 10A Fuse in one of the both Cables between Motor and ESC.

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Offline LukeZ

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Re: TCB in KingTiger
« Reply #7 on: April 13, 2018, 12:55:12 AM »
One thing I not sure about is how much current the gearbox motors can take. They have no rating on them and so with the X45 being able to deliver 45amps you could be in a stall situation or uphill etc and burn the motors out. That is why I fused the ESC's with a 25 amp fuse.
This is a common misunderstanding of the way electronics work. Your motors will draw whatever they will draw, regardless the rating of your batteries or ESC. You can offer a thirsty man a lake to drink, but that does not mean he will drown. He will drink as much as he needs and then stop, even though the supply be infinite.

In fact it is important that your battery and ESC be able to provide more than the maximum your motor will draw, otherwise you risk damaging not the motor but your battery or ESC. Typically as Jurgen says the motor draws the most current when it is completely stalled. If you have an amp-meter you can measure this amount yourself, then you will know exactly where you stand.

Of course it is possible to burn out motors, but when that happens it isn't the current supply that is the cause but rather trying to use an under-powered motor for a heavy job. To use another analogy, if you tried to run a semi truck with a lawn mower engine you would burn out the engine, but it wouldn't have anything to do with the size of the fuel tank.

Your idea of a fuse is still a very good one, although again you'd really want measurements of your system to know what size to use. As Jurgen says, 25 amps may be far beyond the stall current of your motors in which case it will do nothing.

A fuse is a great tool in saving your drive-train during stall conditions. Lot cheaper to replace a fuse than a drive sprocket!

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Offline rockchuck

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Re: TCB in KingTiger
« Reply #8 on: April 13, 2018, 03:25:12 AM »
The reason behind the protection fuse is really about protecting your tank from an extreme over current situation.
I'm not just trying to protect the motor or the esc-- but the whole tank.
We have battery technology that can deliver large amounts of current. The LiPo in my KT can deliver burst currents of 60 amp.

What conditions could make this situation happen. Well a short circuit is the likely cause. Without a fuse you have these currents flowing through your Tank's wiring until the short circuit ceases-- ie is burnt out. There is a high chance that depending on how long that situation goes on for will decide if your expensive tank goes up in flames.

So the wiring in the tank for the power cable I have is rated for 25 amps for a reasonable amount of time but it would not withstand 60amps being pulled thru it.
This situation could occur in the motor for example-- the motor has stalled however the operator has still got the throttle on trying to clear the obstruction etc -- the motor will get hot and can reach a point where the coating on the copper wire windings melt and then you have a short circuit. A short circuit will draw the full amount of battery supply until the short circuit is destroyed usually by fire.
If you have a correctly rated fuse for your installation it will do it's job and stop the extreme over current event and save your tank from going up in flames.
I have experienced this with standard Heng Long tanks with the RX18 board. What happens there is the stalled motor wants more current that the FETS on the RX18 board can deliver and they go up in smoke.

I have fitted fuses to some of my HL tanks (not all yet) and that saved my HL Sherman from burning out the RX18 board. I had a stalled condition where a stick got caught in the tracks and I didn't see it as I was about 20m away. The fuse did it's job-- it was a 8 amp fuse -- I could up this to 10amp ok as the Fets on the rx18 board are good for 12 amp but with no fan and enclosed in it's case I figured 8amps would be a bit safer.

I also fly RC planes and have seen motors burn out. We had a training glider fitted with a buddy wireless control system that was belly landed however the throttle control was left on the Master radio and the prop was stalled into the ground so that motor just kept trying to turn the prop until it burnt out as the battery was happy to supply as much current as  the short circuit in the motor wanted.  It got very hot and the foam started to sag around the nose.   

So it is a safety precaution- a battery under short circuit conditions will deliver huge currents-- look at your car that has fuses-- why not in our tanks!

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Offline jhamm

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Re: TCB in KingTiger
« Reply #9 on: April 13, 2018, 04:00:33 AM »
look at your car that has fuses-- why not in our tanks!

A car have a lot of Fuses.
The Fuses build a chain from Battery to the last electronic device.
At the Tank i use Fuses at:
1. main short circuit protection to Battery = Sum Current of all devices + 10 to 20 %  (seldom more than 30A)
2. protection of ESC = rated Current - 10%
3. protection of Motor = rated stall current
4. protection of the electronic Control unit = rated current (most 1,5 to 3 A)

 

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