Hacking Brushless Speed Controllers to Brushless

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I was looking at the method to hack certain Brushless ESCs into brushed ones - given that's been done with a couple of ESCs by Botbitz with quite large success (notably the TZ85As), I was wondering if anyone knows whether it's possible to do with any brushless speed controller - specifically those that take up to 10/12s+ LiPo and 100+ amps? It's not for anything I specifically need (really, the only use I can think of would be for Magmotors in a Feather/Lightweight or something) rather just curious as to whether it's actually possible.

[overkill]

The answer is "Maybe..." From what I recall, Steve at Botbitz has concentrated on just one family of MCU as he needed to buy a fairly expensive dev kit and some software. You could modify an ESC with just about any MCU but if you change to an ESC with a different brand of MCU, you are up for extra expense.

Other factors:

The code needs to be unlocked or unencrypted. Some MCUs have an option to lock the code permanently, so even if you can read it, it can never be changed. Luckily, it seems that most Chinese ESCs are unlocked.

The MCU and/or the programming pins need to be accessible. If the MCU is buried between two PCBs, its often impossible to re-program it and you have to buy the ESC to find out.

You need to be a super-genius like Steve

BTW: I added a larger heatsink to a TZ85 and used it to run a Magmotor @ 22 volts last year - the ESC hardly got warm in testing. Steve is looking at running long Mag motors in his heavyweight using one or two TZ85's.

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I see... sounds a bit of a gamble then! I'll probably not end up attempting to reprogram any myself because I barely know how ESCs work anyway! I've heard about some motors in heavies being run off 2 ESCs before (Sewer Snake did it at some point, I think?) so I think it'll be doable to use 2 TZ85As for it. If it manages to run on one though, that's very impressive! Might actually be able to build a heavyweight if they're usable for that!

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You are right about Sewer Snake. Mag motors are a special case - they have two electrically separate circuits, so you can run two ESCs without interference. The TZ85 I was using was a special order - Steve turned it into a 'spin controller' that only ran the motor in one direction. The up-side is that it switches on two channels of FETs for more current capacity.

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I see, that might be a good option for my metaphorical heavy, though I'll go out on a limb here and assume mag motors are pretty expensive comparatively?

The spin controller seems pretty handy too for brushed spinners and the like! Are those two channels of FETs split into one for forward, and another for reverse usually?

[maddox10]

A fet (short for mosfet) is a semi conductor, it is only conductive in 1 direction. And only when commanded to be so.

A reversing brushed motor setup with mosfets is in essence an H-Bridge, meaning 4 fets (or a multiple of that) work together to control 1 channel.
For brushless you need 3 reversing channels to create the 3 fase alternating current these motors need. In theory you can hack a brushless speedo, and use all channels to control all 3 outgoing wires as 1. But that's theory. The BotBitz guys just programmed 1 channel away(and snipped off the wire) and use the 2 others as a classic H-bridge.

Magmotor, or ampflow as they are called now, come in all flavors. From -recently- rebranded Chinese scootermotors, to the Old powerhouse A40-300

http://www.robotmarketplace.com/prod...flow_main.html

And you can say the A series are expensive, de F and E series are a lot more affordable, but you get what you pay for.

I myself won't use e'm, modern technology gives us smaller, more economical alternatives.

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I see, that makes a lot of sense! Does the variable speed come from the fets resisting the current at different rates to apply a higher/lower voltage to the motor?

And what alternatives would those be too, if you don't mind me asking? Just getting inspiration for a heavy at this point, figuring out the costs and all that!

[maddox10]

If the fets are acting like a resistor, they will blow in a heartbeat or less. That can happen if the gate isn't powered properly.

No, the basic idea is to switch the fets on and off , with the off cycle longer or shorter to follow the commands. In short, you give the motor bursts of full voltage, and the nature of the thing will make that into an avarage.
Only specialised tools, like osciloscopes can show the pulses. the avarage multimeter will show the avarage voltage. And that's only worth something with brushed setups.

For a heavy, I prefer Iskra's atm. Easy to aquire, not to expensive and rugged to boot. Those are heavier than the magmotors, but thesadays , weight can be found in batteries. 10 or 12S 8400mAh LiFePo4 weights as much as 12V 12Ah SLA.

[RoboLibre]

I'll be reprogramming some of the TZ85a escs eventually, things are pretty busy at the moment, but they are in the pipeline

As a rule of thumb, it is usually escs that run atmel chips that are more easily programmable...
However as Nick says, some of these can be locked.
Occasionally locked escs can be force wiped, then have custom firmware flashed to them, but it can be a unreliable process with some risk involved to the longevity of the chip if done incorrectly...

Alternatively... some locked escs can have the chip removed and a new blank atmel mcu soldered in and flashed with the custom firmware, but you must be proficient in soldering to achieve this.

I usually use a needle point tip on a temp controlled antex iron, with either super fine solder, or solder paste.
Focused heat flashing can be used, but I prefer to see every joint formed individually =)

Currently looking into other escs that could be converted... looking for something cheap but reliable... or at least with some potential to inflict moddige upon

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If the ESC says anything about having a super-fast MCU, its probably using a Silicon Labs chip. Castle Creations started using Silabs chips and they got cloned pretty quickly.