Esc Advice

So, building is underway now (I sanded down two edges on a shell I bought from Harry) on my new featherweight. I have motors sorted out, and a battery in mind (Ni-MH. Not LiPo just yet). The only thing left is which Esc I should pick. Due to my very limited budget, I'm going to use two speed controllers for a 4wd setup. My options consist of two of those eBay 320A dual ones. They say they can brake and there are dual motor models (still getting two though, one for each side). The question I have is as followed: do they brake or not? I can more or less work my way around the control issues, just the braking I need to know. Alternatively, I can use a pair of hobbywing dual quickruns. The dual motor option goes up to 12 cells (Ni-MH, I work with those numbers), 2 more than I need. They do cost twice as much, and I'm not sure it comes with a fan. Thanks.

Forget the "cheap" options. In the short run, they will be more expensive, even if they can do the job halfassed.

Better to save up a bit, and buy a good one to start with. We're using the IBF 4.5 in our raptors and feathers.
Not the most powerfull ESC, but those 2x40 Deutsche Grundlicheids ampères outshine the 320 Chinese ampère el cheapos in any respect.

People do run Quicruns in competition so they are doable. I had a couple blow up the other weekend but to be fair I was using meaty motors and 75c 4s LIPOs and I think my signal mixer was playing up too.

Would they work for testing, though? To be honest, I just want a pair of speed controllers that drive the motors for now, I don't think I'll be able to make any events for another 6 months to a year (depending on if robot wars does a FW tournament). So, would the cheap eBay ones do the trick just for testing? Do they brake? (key question) ​Thanks.

Buy a pre-built one "Feather2" from Rory.

I would, but I'm not sure they can run four 550S motors. It only says 2 in the doc. I'm going to buy 2 of those cheap eBay ones just for testing. They're £10 each so not too much of a loss. After, I might get a couple of Botbitz 30A controllers and modify them to run 2 motors each on the same channel (if that's possible), or a couple, of hobbywing dual controllers, or a Feather2 if it can do 4WD (plus I can get it repaired at a reasonable cost).

Those cheap ones are probably only good for a car or truck. The 'brake' as on the one I have, basically means that you cant go directly from Rev to Fwd without having to stop in the neutral position. For a car or truck that's OK, but for a robot that is using tank steering it means you cant easily steer or drive it. There are ones without the brake function, but they seem to be import only from china.

well depending how "cheap" you want to go, you could get some Turnigy TZ85a ESCs re program them at £36 each , and they would do you great, however you can get them pre done but for another £28.50.

Side note, where does one buy a Feather2 and can someone link it's spec sheet?

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Originally Posted by Maxamuslead

well depending how "cheap" you want to go, you could get some Turnigy TZ85a ESCs re program them at £36 each , and they would do you great, however you can get them pre done but for another £28.50.

Side note, where does one buy a Feather2 and can someone link it's spec sheet?

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Rapid Rory makes and sells the FeatherTwo, plus Ant controllers:
http://www.fightingrobots.co.uk/members/1557-rapidrory

I'll be messaging Rory at some point to enquire about them. I remember a post by him ages ago saying it can run in 4WD, or that could be his beetleweight controller instead. In any case, I'll be ordering two cheap eBay speed controllers (on Amazon ironically) to test everything out. My only concern with a dual controller is if one's damaged, the whole drive is gone, with singles they can easily be replaced. Though the repair offer is good to know. Thanks. I should be opening a build diary very soon so I can get some more advice as I go along. Thanks again.

Luna-tic currently runs on hobbywing quicruns 860, the duel (double output for two motors). Worked fine for 8 fights at Manchester. I say fine and currently, the bot can turn while speeding up or slowing down, might be something to do with the greater resistance when the esc is "reversing"...?! I'm not an electrician. lol. I will be getting One of Rorys ESC's (which controls both the left and right motor) when money permits. And for the price of £55 (last checked) its the same as two quicruns anyway. I do read Rory can get quite bogged down building and repairing ESC's, so best to message him to see what his current work load is like!!

The Feather2 seems brilliant value, its just the risk of it being one controller for all motors. I guess mounting it in the middle around a ton of foam would be fine. How were the quicruns? did they overheat or run okay? How fragile were they? I'm sorry, just you're the only person I can find with any experience with them. Thanks

If 1 ESC blows during a fight, you're out whatsoever. Most RW specific "dual" ESC's have anb advantage if it comes to set them up and get the 2 motors working together to drive a straight line.

The IBF series have the option to add a gyro. For fast, 2WD narrow wheelbase machines it's a big advantage.

I mean for maintenance. if I lose one ESC (let's say botbitz 30A) then I can swap it out for another (an extra £30) but if I lose a dual ESC, replacing it will cost £60. in any case, I'm still probably going to get one for convenience, value and it'll last a good while.

As the Rory ESC, the IBF has a very extensive support. Reiner is very helpfull, a common trait if you ask me.
Rory and Ian have demonstrated such in the past too.

All three still work, 2 for drive (running two motors each) the third for the Linear Actuator. Held in place by a zip tie and a bit of foam padding between them and the HDPE chassis. After the weekend of 8 fights they we're working loose. But suppose I should also point out, I wasn't facing any spinners or massive flippers. Manchester was more of a pushing and shoving battle. For testing and playing they will be fine. The feather rumbles at the live events, again should be fine. But serious full on combat like the UK championships.. Guess I'll find out once they publish a date!!

I use a 4s lipo (15v) and 4 cheap cordless drill motors. The rated 60amp on the box I wouldn't believe, I've read lots of stories of Chinese Amps compared to normal amps. But doubt the motor would draw anywhere near that anyway. (suppose I should really change my fuse for a smaller one, just incase. Currently have a 100amp installed. lol. That's another way to ensure its a tad more protected, use a fuse whos amps are lower than the esc's rated MAX.....

The only problems I had was my driving into the pit, (again not helped by the bot turning during acceleration and braking occasionally), The bottom hinge of my actuator bending and sticking out the bottom of the chassis lifting my wheels off the ground and a receiver plug falling out.

Asking for advise, you're in the best place, I was where you are 6-9 months ago. But there comes a stage you just need to take the plunge, buy and test it. I'm doing the same with my heavy at the moment. Constantly online checking specs of components and looking inside everyone's bot, to see what they do, what works. I need to place that damn order and just connect everything up, but worried I'm wasting 100's of pounds. Why starting with feathers is much more wallet friendly, mistakes only cost 10's of pounds......

Several points during this video, you can see the bot turn slightly to the right after I let go of the stick. I don't know why, I'm guessing its the esc's, on the spec sheets it mentions the resistance is higher when in reverse. Always one of the motors/esc is in reverse when traveling in a straight line!! perhaps someone with more knowledge could explain!!?

https://www.youtube.com/watch?v=vTqx...LrywRk&index=8

The thing as well for the ESCs from Rory as the IBF ones is, both can also do repairs on them.
And... well, the IBF one at least got a fuse itself, so to actually damage it, you'd need physical damage to it.
Place it somewhere nice and safe in the bot with some shock mounting, and that should do the trick.
Most bots i've seen became unmaneuverable due to loss of wheels and such way before anything ever came close to the expensive electronic parts. sometimes switch out a motor or gearbox, but that's it.

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Originally Posted by cjsowry

Several points during this video, you can see the bot turn slightly to the right after I let go of the stick. I don't know why, I'm guessing its the esc's, on the spec sheets it mentions the resistance is higher when in reverse. Always one of the motors/esc is in reverse when traveling in a straight line!! perhaps someone with more knowledge could explain!!?

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To me it just looks like a trimming issue causing one side not to go into brake. Make sure to do a full trim:

Apologise in advance this may be a tad patronising, I just copied it from my custom antweight care sheets.

"Your robot should be controlled but it may not be quite right, the wheels may try and turn on their own or the flipper may not go all the way down. These are fixed with trims, they simply nudge where the middle position of the joystick. Your trim controls are the buttons immediately to the side and below the joysticks. If your robot is trying to steer left or right simply press the trim button in the opposite direction on your steering stick until it doesn’t, the same applies to the forwards and backwards. The easiest way to do this is to position the robot the right way up but with all wheels lifted off the ground, when you push forwards on the stick all wheels should start at the same time. If they do not make a note of which way the robot would be turning and click the trim in the opposite direction. Keep repeating until all the wheels begin turning at the same time. Now use the steering stick to turn the robot, again both wheels should begin turning at the same time. If they do not not if the wheel that is moving first is going forwards or backwards, click the trim for forwards and backwards in the opposite direction. Keep repeating until all the wheels begin turning at the same time. "

The resistance things *shouldn't* be the cause, that'd manifest as one side of the ESC becoming hotter. Unless the have a firmware difference in how they brake from forwards or reverse, but that'd be an odd thing to do.

Normally mechanically uneven drive is more a concern with bias timed motors like dewalts. Where one running backwards gets much hotter than the other, never noticed a power difference in my dewalt bot though.

The el cheapo ESC's from Ebay (the Blue's), have a limited reverse, like 50%, and also do have a brake bias depending change of direction.

Those combined with small differences in timing (even center timed) on the equaly inexpensive motors used in batterydrills will give an noticable inbalance in drive.

One of the reasons some of the machines use a gyro, and the main reason why team RCC prefers RW specific controlers like the Scorpion XXL mk1 or IBF 4.X

Those can be trimmed, adjusted and pampered to an extend even modern RX/TX sets can't do with single drive ESC's ,even with extensive reprogramming.

Like I said, I'm going to get 2 dual 'blues' for testing, then a Feather2 both when I find out they can run 4 motors and les not completely busy

We smoked more of the Blues in 2004-6 than I care for. Gets stale fast, those smokebombs.

That stopped once we went Scorpion XXL Iliama version.