Dual ESC

[aPpYe]

Hello, I am brand new to the MOA thing, so please forgive me. Looking at the Bully Bible on this forum, it states:

Duel ESC will give the ability to run each motor independently at its own speed as long as you have a radio that lets you. The popular ESC are a Tekin FXR, Castle creations micro sidewinder or the Holmes Hobbies BR mini. Everybody seems to have preference on their ESC so search around.

... Does this mean it will work this way (run each motor independently at its own speed) with a "Dual ESC" like the Hobbywing 880 or the Holmes Hobbies Torquemaster BR Mini Dual or was this statement more about running two separate ESC's?

This is my first crawler build, and I am just doing this for fun, but I do want to maximize the capability of my rig. As far as speed control goes, I definitely want to be able to have both a front and rear dig, and being able to independently set motor speeds seems like a definite plus as well.

I am not really sure where to start with making a decision on ESC and motors, and haven't even begun researching receivers, transmitters, BEC's, dig units etc.

... Help?

Thanks for your time!

 

[HumboldtEF]

You'll want 2 separate ESCs not a dual ESC. The Holmes BR mini dual is actually 2 separate ESCs where as the HW 880 is a single ESC that can handle 2 motors.

 

[aPpYe]

You'll want 2 separate ESCs not a dual ESC. The Holmes BR mini dual is actually 2 separate ESCs where as the HW 880 is a single ESC that can handle 2 motors.

I kind of thought that was the case. it seems simpler in a way because the two separate esc's would be able to act as digs? Thanks for the info!

Any recommendations?

 

[HumboldtEF]

Yeah the separate ESCs will be able to have dig, its the best setup. You can easily adjust how this functions and even use it to add overdrive by speeding up or slowing down one motor.

You can also get dig with a single dual motor ESC by using a dig switch https://store.rc4wd.com/Rocker-Dig-II-Electronic-for-MOA-Crawler_p_1321.html
These dont offer any adjustability and probably shouldnt be considered, its RTR grade.

 

[aPpYe]

It looks like I will be going with separate esc's then. Now I need to start researching them. Any recommendations there as well? Thanks for all your input by the way. What about receivers and transmitters? I got my rear steering parts on the way. The mechanical parts anyway.

 

[HumboldtEF]

I've used the Holmes Hobbies dual BR mini, its a stripped down version of their torquemaster ESC which is a decent ESC. By stripped down I mean it has no casing and no heat sink so this isnt aimed at long run times or setups that may create lots of heat (from high gearing or high wheelspeed). These are more appropriate on a lightweight MOA in a competition setting (short runs).

If you feel like you might need more cooling capacity you could consider a non stripped down ESC like the Tekin BXR, its nice and compact. I will say that I'm not a big fan of their software and the lack of auto cell detection, you actually have to program you ESC for the 2S or 3S and if you switch you need to re-program it. Thats not a issue if you plan to stick to one battery though. I have seen a few recent threads where folks were having issues with this ESC not arming, not sure on the details though.

I've been happy using Spektrum for radios and receivers, FLY Sky GT5 is also a popular inexpensive but highly programable radio.

I'm happy to help "thumbsup"

 

[aPpYe]

Hmm. Okay. I definitely don't want to overheat anything. The bully2 wouldn't be that great of a trail rig, I wouldn't think so anyway. What is a typical top speed with one of these using something akin to average electronics? Also I would think I am going to be using a small battery so runtimes wouldn't be that long...

That being said, I do plan on crawling for decent periods. I have a group of guys that gets together on the weekends for beers and crawling for some hours.

 

[HumboldtEF]

The bully 2 isn't the most ideal trail rig due to the small battery, but you can just bring more batteries.

You can probably get walking speed out of the average Bully 2 but it all depends on the motors and gearing.

 

[Minoa]

I'll chime in with my 2 cents of opinions... I run 2 1080s paired with 2 HH 45t trailnasters, powered with cheap 1500mah 3S batteries on stock gearing. I get over 2hrs of run time and slightly faster than walking speed.

Regulars to the Bully section probably get tired of reading my posts because I always recommend "differential throttle", at least thats what the plane guys call it so that's what I go with. Using a dual stick transmitter, you can control each axle separately getting both dig and overdrive on either axle just with the sticks, no buttons, switches, or dials needed. I only bash my Bully around woods, creeks, and trails, no comps but I still use dig and overdrive often. Becomes 2nd nature after a couple runs, love it.

 

[HumboldtEF]

powered with cheap 1500mah 3S batteries on stock gearing.

Where do you put the battery? in the chassis? I was thinking that would allow for a much longer run time.

 

[Minoa]

I had a buddy laser cut a couple battery trays, have a battery on each axle. Rear axle also has one of the 1080s. If I remember correctly, I had him cut a couple that were wider than the stock battery tray to accommodate the thicker 3S battery but the same length as the stock battery tray. Works great. I'd post a picture but I can't figure out how.

 

[aPpYe]

That sounds pretty cool. 1500 batteries sound like they might weigh a bit? I hadn't thought about using a dual stick controller. It might actually be the way to go, allowing immediate control over steering and throttle for both axles without having to fuss with buttons and different steering and throttle "modes," etc. This vacation has been taking up so much of my time I have had had little time to actually research this stuff. thanks for that tip! Is this all with one receiver? I imagine the esc's are both axle mounted and the receiver is the only electronics in the chassis?

... Figure out how to post some pictures! I'd really like to see this!

 

[HumboldtEF]

I'd post a picture but I can't figure out how.

To post pics you'll need to either become a member here or you can use a image hosting site like Imgur.

http://www.rccrawler.com/forum/comments-suggestions-help/617767-imgur-embedding-posting-photos.html

 

[aPpYe]

Is there a premium membership or something? Myself, I have been using Google Photos for forum images ...

 

[wander]

http://www.rccrawler.com/forum/payments.php

 

[aPpYe]

Regulars to the Bully section probably get tired of reading my posts because I always recommend "differential throttle", at least thats what the plane guys call it so that's what I go with. Using a dual stick transmitter, you can control each axle separately getting both dig and overdrive on either axle just with the sticks, no buttons, switches, or dials needed. I only bash my Bully around woods, creeks, and trails, no comps but I still use dig and overdrive often. Becomes 2nd nature after a couple runs, love it.

The simplicity of this really has me thinking! I am going to have rear steering as well, so I count 4 channels for my setup, does that sound right? Basically one stick for each axle, both throttle and steering, unless I am (probably!) missing something ...

Will any receivers will pair with my DJI (Mini 2) remote? Probably not, but worth asking I guess ...

I have never used a BEC before, but I am thinking I would want to have ESCs with a BEC on them, like your 1080's. I would guess the steering channel plugs into the ESC (BEC) which relays that signal (and more voltage/amperage/power) to the servo. Is that right?

I am on vacation for another couple weeks and I was bummed to find out I forgot to have the bully shipped down here. It was shipped to my house instead, and now has a vacation hold on it. Oh well. This means I have more time to pick your brains before I even pick up a screwdriver.

 

[HumboldtEF]

The simplicity of this really has me thinking! I am going to have rear steering as well, so I count 4 channels for my setup, does that sound right? Basically one stick for each axle, both throttle and steering, unless I am (probably!) missing something ...

Will any receivers will pair with my DJI (Mini 2) remote? Probably not, but worth asking I guess ...

I have never used a BEC before, but I am thinking I would want to have ESCs with a BEC on them, like your 1080's. I would guess the steering channel plugs into the ESC (BEC) which relays that signal (and more voltage/amperage/power) to the servo. Is that right?

I am on vacation for another couple weeks and I was bummed to find out I forgot to have the bully shipped down here. It was shipped to my house instead, and now has a vacation hold on it. Oh well. This means I have more time to pick your brains before I even pick up a screwdriver.

You will need at least 2 auxiliary channels, Channel 1 and 2 are for steering and ESC but you'll need 2 additional aux channels to run the extra servo and ESC.
channel 1= front steering
channel 2= ESC 1
channel 3 (any aux) = ESC 2
Channel 4 (any other aux)= rear steering
If external BEC: channel 5 (any aux or battery channel)=external BEC

You will probably need an external BEC which can either be plugged straight into the receiver so long as your under its voltage limit (this sends the BEC voltage through the receiver not the ESC). This will require another free channel but it can be a Battery channel. The other route is to use a bypass adapter which sends the BEC voltage to the servos only, these can be purchased or made if you have the supplies.

If you try to use the internal BEC of a ESC keep in mind the amperage it puts out will be split between the 2 servos. Depending on how amp hungry your servos are this might be fine or it may start to brown out indicating a need for a better (external) BEC. When using a exteral BEC just remember to remove the remaining red wire from the ESC plug so you dont double power the receiver and cause problems. Also worth nothing here, running 2 ESC's will require that you remove one of the red wires from 1 of the ESC plugs after calibrating and getting each setup.

I have no knowledge of DJI or drones but receivers and transmitters almost always use a specific protocol which means you need to use their specific receiver or look for one that advertises as compatible. You probably can find a receiver for a DJI since its so popular a brand.

 

[aPpYe]

Okay so I am thinking the plan will be to go with two ESC's, each powering a servo with the internal BEC. If I have issues I will add an external BEC.

I am still weighing whether or not I want one or two batteries, and I am also looking at some of the brushless systems as well (Hobbywing's QuicRun Fusion FOC System 2in1 looks sexy).

As for internal BEC, how does this wire up? I only have experience plugging a servo directly into the receiver. How does it work powering the servo off of the (integrated BEC) ESC? My thought is that there would have to be two input ports on the ESC (one for the motor and one for the servo) and then another port for the servo itself. Is this at all how things work? Maybe someone can point me to a wiring diagram ...

 

[HumboldtEF]

Have a look here: https://www.bigsquidrc.com/everybodys-scalin-explaining-the-bec/

 

[aPpYe]

Okay, so this works totally different than I had imagined, kind of a relay that received a signal from the receiver and sort of amplified it. In reality it is more (exactly?) like a voltage regulator that is directly connected to the battery. I would guess that's why I don't see any wiring diagrams for an internal BEC, this regulator being integrated into the ESC would mean the receiver gets its higher voltage/amperage from the ESC plug.

Am I now understanding this correctly?

channel 1= front steering
channel 2= ESC 1
channel 3 (any aux) = ESC 2
Channel 4 (any other aux)= rear steering

... If I wire it up as indicated above, is it still safe, seeing as how two BECs would be plugged into the receiver? Is it okay to plug two identical ESCs, each with their own internal BEC, to a single receiver? I am thinking I will start without an external BEC, the idea being that each servo will be powered by its own dedicated (internal/integrated) BEC.

If you try to use the internal BEC of a ESC keep in mind the amperage it puts out will be split between the 2 servos.

With the two ESCs, would the ESC on channel 2 power the servo on channel 1 while the ESC on channel 3 powers the servo on channel 4? Is it more like a parallel circuit with a larger pool of overall amperage to pull from? At what point will I overload a typical receiver board?

Also, I have seen wiring diagrams (external BEC) where the positive and negative wires bypass the receiver, connecting directly to the servo. The signal(?) wire is still connected to the receiver. Is this possible with an internal BEC?