Wheeled RC Tank Build

[SomeGuy]

So I started the first project I'm going to use my lathe for, a wheeled RC tank. I started with putting together the electronics, though ran into an issue where the PWM used by the radio receiver and the motor drivers doesn't match. So looks like I need different motor drivers...but otherwise, pretty neat to get it running.



I'll be also doing this on the YouTube channel I started that I mention in the other thread. If you want to see me put this stuff together and a few more details, it's here:

 

[Everett]

I like the idea of using a standardized swappable battery like you are. Means your tools and toys use the same standard, lol. This is going to be cool.

 

[SomeGuy]

I like the idea of using a standardized swappable battery like you are. Means your tools and toys use the same standard, lol. This is going to be cool.

Yup, I've got a pile of them and technically it's equivalent to a 5S RC battery and uses 18650 cells and you can draw something like 50 amps from them peak (though I expect to be around 10 amps). We'll see how it goes, since the motor is peak efficiency at 24v and could take as high as 36v if you want, so they'll run a bit slower.

 

[PeterT]

Interesting, I'll have to start following along. I've been in RC a long time but my knowledge ends at the fringe of regular RC equipment. And when it comes to PWM & signal processing my eyes glaze over LOL.
@CalgaryPT probably has a handle on this stuff. All I can say is that even amongst the branded mainstream RC radio manufacturers, its to a point that none of them are on speaking terms with one another, meaning the receiver protocols. JR used to talk Spectrum, but different that Futaba, Jeti, Taranis... Reason I mention is if you have to program specific channels to drive the wheel motors or other features in the future, the TX choice would have a trickle effect to RX features/suitability. By this I mean mixing, end points, rates etc. A more basic TX will be limited as to what it can do. I'm sure this stuff is RobotClub 101 but outside my scope. Most of the robot war stuff I see looks like they have a typical RC 8+ch radio. I don't fly Taranus but if you are into programming, that seems to be popular with RC/hobbyist folks who want to define every button & stick movement to do whatever (vs being more constrained by how a typical RC TX is laid out).

I'm curious about the 20v 5 A-hr packs. I'm guessing maybe 10 cells, bank of 5 in series to get 5*4=20v nominal? And you are putting 2 packs in parallel to get 20v x 10 A-hr?
So 50A max draw / 10 A-hr = 5C equivalent. Is that what 18650 cells can do? I tried Googling specs but they seem to vary all over the map.

 

[SomeGuy]

Interesting, I'll have to start following along. I've been in RC a long time but my knowledge ends at the fringe of regular RC equipment. And when it comes to PWM & signal processing my eyes glaze over LOL.
@CalgaryPT probably has a handle on this stuff. All I can say is that even amongst the branded mainstream RC radio manufacturers, its to a point that none of them are on speaking terms with one another, meaning the receiver protocols. JR used to talk Spectrum, but different that Futaba, Jeti, Taranis... Reason I mention is if you have to program specific channels to drive the wheel motors or other features in the future, the TX choice would have a trickle effect to RX features/suitability. By this I mean mixing, end points, rates etc. A more basic TX will be limited as to what it can do. I'm sure this stuff is RobotClub 101 but outside my scope. Most of the robot war stuff I see looks like they have a typical RC 8+ch radio. I don't fly Taranus but if you are into programming, that seems to be popular with RC/hobbyist folks who want to define every button & stick movement to do whatever (vs being more constrained by how a typical RC TX is laid out).

I'm curious about the 20v 5 A-hr packs. I'm guessing maybe 10 cells, bank of 5 in series to get 5*4=20v nominal? And you are putting 2 packs in parallel to get 20v x 10 A-hr?
So 50A max draw / 10 A-hr = 5C equivalent. Is that what 18650 cells can do? I tried Googling specs but they seem to vary all over the map.

The problem I have is between the receiver and the motor driver...not the transmitter and receiver. I'm not about to start mucking with different TX/RX combos, the one I got has 6 channels so I have a few optional hookups if I need them (I might put a little snow plow on the front of this lol).

As for the packs, I think you're spot on...should be 10 x 18650 cells, 5 each in series than parallel together from what I've seen/read. As I wired in the vid, packs are independent, one for left one for right. So effectively getting 10ah but not using them in parallel. We'll see how they end up working, worst case I have to get real lipo packs but I have tons of these batteries on hand so if they work I'm ahead.

 

[PeterT]

I guess I was suggesting (guessing really) that the output protocols might vary by RX brand too & what your driver might be expecting maybe not be what your RX is delivering. Only reason I say this is the configuration & wiring can vary with ESC's & other do-dads like the heli & drone guys plug into.

RC radio control protocols explained: PWM, PPM, PCM, SBUS, IBUS DSMX, DSM2

This guide will explain the various radio control receiver protocols that you are likely to come across in this drone hobby. So next time it comes to buying some new R/C receiver, or setting up your R/C receiver with your flight controller you will know exactly what all the acronyms mean and...

www.dronetrest.com

Home | MULTI-Module Documentation

www.multi-module.org

I didn't think 18650 C-rating was that high, but as mentioned, internet specs are all over the map. This link suggests Continuous = ~1 (2750/2850). Burst/high = ~ 3 (8250/2850) .

https://components101.com/sites/default/files/component_datasheet/18650%20Lithium%20Cell%20Datasheet.pdf

 

[SomeGuy]

I guess I was suggesting (guessing really) that the output protocols might vary by RX brand too & what your driver might be expecting maybe not be what your RX is delivering. Only reason I say this is the configuration & wiring can vary with ESC's & other do-dads like the heli & drone guys plug into.

RC radio control protocols explained: PWM, PPM, PCM, SBUS, IBUS DSMX, DSM2

This guide will explain the various radio control receiver protocols that you are likely to come across in this drone hobby. So next time it comes to buying some new R/C receiver, or setting up your R/C receiver with your flight controller you will know exactly what all the acronyms mean and...

www.dronetrest.com

Home | MULTI-Module Documentation

www.multi-module.org

I didn't think 18650 C-rating was that high, but as mentioned, internet specs are all over the map. This link suggests Continuous = ~1 (2750/2850). Burst/high = ~ 3 (8250/2850) .

https://components101.com/sites/default/files/component_datasheet/18650%20Lithium%20Cell%20Datasheet.pdf

Yeah, I've seen all those other protocols. Both of the things I bought said "PWM" so that's why I figured they'd work together...but I guess RC PWM is different than regular PWM, and the motor driver does regular PWM, the RC does a special one where it uses 1.5ms, 1.0ms, and 2.0ms pulses for "middle" "low" and "high". At least from what I've read.

We'll see how the batteries do, I know in my grinder or leaf blower I can drain the entire battery in 15 minutes of use. So based on that, I should be safely able to draw 20 amps? 4C?

 

[PeterT]

Maybe, maybe not. The pre-built tool packs probably have current and/or temperature sensing smarts on the circuit board thingy to protect the cells & shut it down. It might allow what it deems as 'danger zone' current level for short X amount of time, but my guess is it would be programmed conservative to protect the pack. You could test it of course monitoring current. I've never seen a reset button any cordless tool so I think the net result is on=acceptable load, off=nope, not gunna do it LOL. I've heard of people with fried boards but that could be any number of things. Also heard of people gutting the cells out divorcing it from the tool case/board, but now you've lost all your well intentioned functionality. A crap grade 5S RC lipo is 25C cont 50C burst, but you know all that I'm guessing.

 

[LRSbm146]

@SomeGuy what esc’s are you using? They look pretty similar to what I’ve seen go into electric skateboards. There has to be more information on the protocol.... some kind of a code. PPM and PWM are a little bit generic.
All my drones and Helis fly on ppm but like @PeterT mentioned each brand does there own versions.
All of my drones are on taranis, as they brought a lot of new features to the table that previous brands didn’t have. The first being open source software to program the remote called openTX.
A simple solution to your communication issue might be switching to a “multi protocol” transmitter. Can probably find something for around $100 with 12-16 channels and most run OPENTX. OpenTX also makes programming a little more streamlined compared to doing it on the Tx screen.... things like mixing channels together. Might have some good features for a guy building a tank.

 

[CalgaryPT]

So I started the first project I'm going to use my lathe for, a wheeled RC tank. I started with putting together the electronics, though ran into an issue where the PWM used by the radio receiver and the motor drivers doesn't match. So looks like I need different motor drivers...but otherwise, pretty neat to get it running.

View attachment 19848

I'll be also doing this on the YouTube channel I started that I mention in the other thread. If you want to see me put this stuff together and a few more details, it's here:

Looks like a great project. I'm curious why you went with a car transmitter as opposed to an air model for a robot?

 

[SomeGuy]

Maybe, maybe not. The pre-built tool packs probably have current and/or temperature sensing smarts on the circuit board thingy to protect the cells & shut it down. It might allow what it deems as 'danger zone' current level for short X amount of time, but my guess is it would be programmed conservative to protect the pack. You could test it of course monitoring current. I've never seen a reset button any cordless tool so I think the net result is on=acceptable load, off=nope, not gunna do it LOL. I've heard of people with fried boards but that could be any number of things. Also heard of people gutting the cells out divorcing it from the tool case/board, but now you've lost all your well intentioned functionality. A crap grade 5S RC lipo is 25C cont 50C burst, but you know all that I'm guessing.

I didn't know that...25C sounds like a lot of current. Honestly, given the motors are 250 watts rated (continuous), even if I draw 20 amps (roughly 500 watts on these packs) peak, I should be ok. We'll see how it goes and like I said, I can always switch.

@SomeGuy what esc’s are you using? They look pretty similar to what I’ve seen go into electric skateboards. There has to be more information on the protocol.... some kind of a code. PPM and PWM are a little bit generic.
All my drones and Helis fly on ppm but like @PeterT mentioned each brand does there own versions.
All of my drones are on taranis, as they brought a lot of new features to the table that previous brands didn’t have. The first being open source software to program the remote called openTX.
A simple solution to your communication issue might be switching to a “multi protocol” transmitter. Can probably find something for around $100 with 12-16 channels and most run OPENTX. OpenTX also makes programming a little more streamlined compared to doing it on the Tx screen.... things like mixing channels together. Might have some good features for a guy building a tank.

I have these ones, they didn't work:

Cytron 30A 5-30V Single Brushed DC Motor Driver

Description Cytron 30A 5-30V Single Brushed DC Motor Driver Bi-directional control for 1 brushed DC motor Maximum current: 80A peak (1 second), 30A continuously Motor voltage: 5V - 30V 3.3V and 5V logic level input The 30A 5-30V Single Brushed DC Motor Driver is designed to drive medium to high...

www.robotshop.com

Thinking of switching to these ones:

Cytron Single 10- 45V, 40A Brushed DC Motor Controller

Description Bi-directional control for a single brushed DC motor Support motor from 10V to 45V Maximum current up to 80A peak Reduce to 40A gradually according to temperature The Cytron Single 10- 45V, 40A Brushed DC Motor Controller is designed to drive a brushed DC motor, ranging from medium...

www.robotshop.com

Like I mentioned, it's between the receiver and ESC...not the transmitter and receiver (they came together). RC PWM is just not the same...

Looks like a great project. I'm curious why you went with a car transmitter as opposed to an air model for a robot?

It was cheap and has a mixing mode that can be programmed on the controller itself rather than using clunky software that might not work on windows 10...that's about it. This one was $80 with the transmitter and receiver....versus around double that for any two stick one with onboard programming.

 

[CalgaryPT]

I didn't know that...25C sounds like a lot of current. Honestly, given the motors are 250 watts rated (continuous), even if I draw 20 amps (roughly 500 watts on these packs) peak, I should be ok. We'll see how it goes and like I said, I can always switch.


I have these ones, they didn't work:

Cytron 30A 5-30V Single Brushed DC Motor Driver

Description Cytron 30A 5-30V Single Brushed DC Motor Driver Bi-directional control for 1 brushed DC motor Maximum current: 80A peak (1 second), 30A continuously Motor voltage: 5V - 30V 3.3V and 5V logic level input The 30A 5-30V Single Brushed DC Motor Driver is designed to drive medium to high...

www.robotshop.com

Thinking of switching to these ones:

Cytron Single 10- 45V, 40A Brushed DC Motor Controller

Description Bi-directional control for a single brushed DC motor Support motor from 10V to 45V Maximum current up to 80A peak Reduce to 40A gradually according to temperature The Cytron Single 10- 45V, 40A Brushed DC Motor Controller is designed to drive a brushed DC motor, ranging from medium...

www.robotshop.com

Like I mentioned, it's between the receiver and ESC...not the transmitter and receiver (they came together). RC PWM is just not the same...



It was cheap and has a mixing mode that can be programmed on the controller itself rather than using clunky software that might not work on windows 10...that's about it. This one was $80 with the transmitter and receiver....versus around double that for any two stick one with onboard programming.

Gottcha. Please post your build. Great project with lots of fabrication, electronics, etc.

Are you adding any auxiliary control functions such as turret, gun, etc?

 

[LRSbm146]

@SomeGuy that second esc definitely sounds a little more plug and play

 

[SomeGuy]

Gottcha. Please post your build. Great project with lots of fabrication, electronics, etc.

Are you adding any auxiliary control functions such as turret, gun, etc?

I'm thinking snow plow I am very much a functional over aesthetic type of person, so there will be little to no decoration. At most some flat black paint lol

Will post as I go, probably going to order new motor drivers this evening.

 

[Tom O]

Paul has a hell of a lot of videos on robotics , AI, and programming amongst other things.

 

[SomeGuy]

Paul has a hell of a lot of videos on robotics , AI, and programming amongst other things.

I skimmed the video, some neat stuff there.

Funny enough, I do software for a living, so that side of things including AI (I run an R&D group) I'm quite decently versed in.

 

[YYCHM]

Funny enough, I do software for a living, so that side of things including AI (I run an R&D group) I'm quite decently versed in.

Yet another bit shifter joins us...... 30 years of SCADA sw for me.

 

[SomeGuy]

Yet another bit shifter joins us...... 30 years of SCADA sw for me.

I mostly play in the Microsoft tools....Visual Studio with c# and .net, SQL Server, Xamarin, Azure, etc. doing software for enterprise applications. Almost everyone here will have been impacted by software I helped design and build several times in their life, it's pretty cool

Total OT though lol

 

[PeterT]

I didn't know that...25C sounds like a lot of current. Honestly, given the motors are 250 watts rated (continuous), even if I draw 20 amps (roughly 500 watts on these packs) peak, I should be ok. We'll see how it goes and like I said, I can always switch.

25C continuous is old news (lithium polymer not lithium ion) heap these days. Lets see, what's the current state of the day? Oh, there ya go 100C continuous, 200C burst. Yowza.

2S 7.4V 8000mAh 100C-200C LiPo Battery w/ XT60 Plug + Traxxas

2S 7.4V 8000mAh 100C-200C LiPo Battery w/ XT60 Plug + Traxxas

www.canadahobbies.ca

But I agree, match your packs to the motor requirements. Depending on the application, the battery price / capacity / other characteristics can sometimes dictate motor selection especially if the motor price is similar across different KV flavors.

ps I just realized something, those are brushed motors right? I was just starting to hunt around for a 'gadget' motor something like this. Is Ampflow a decent name?

AmpFlow E30-150 Brushed Electric Motor, 12V, 24V or 36 VDC, 5600 RPM : Amazon.ca: Tools & Home Improvement

AmpFlow E30-150 Brushed Electric Motor, 12V, 24V or 36 VDC, 5600 RPM : Amazon.ca: Tools & Home Improvement

www.amazon.ca

 

[SomeGuy]

25C continuous is old news (lithium polymer not lithium ion) heap these days. Lets see, what's the current state of the day? Oh, there ya go 100C continuous, 200C burst. Yowza.

2S 7.4V 8000mAh 100C-200C LiPo Battery w/ XT60 Plug + Traxxas

2S 7.4V 8000mAh 100C-200C LiPo Battery w/ XT60 Plug + Traxxas

www.canadahobbies.ca

But I agree, match your packs to the motor requirements. Depending on the application, the battery price / capacity / other characteristics can sometimes dictate motor selection especially if the motor price is similar across different KV flavors.

ps I just realized something, those are brushed motors right? I was just starting to hunt around for a 'gadget' motor something like this. Is Ampflow a decent name?

AmpFlow E30-150 Brushed Electric Motor, 12V, 24V or 36 VDC, 5600 RPM : Amazon.ca: Tools & Home Improvement

AmpFlow E30-150 Brushed Electric Motor, 12V, 24V or 36 VDC, 5600 RPM : Amazon.ca: Tools & Home Improvement

www.amazon.ca

Also being a budget build, it's kinda trying to not go overboard with the best of everything...especially when I clearly don't know what I'm doing. I'd rather burn up a Dewalt pack that is easily replaced than a few hundred of lipos.

Yeah they're brushed motors, seems decent for the price although I haven't gotten them under any load yet. I have the P40-250's.