Beginner Question Thread! 2023 Edition

[Geo_Engineering_FTW]

What are people thoughts on these MakerX 6354 motors? seem like the old flipsky ones before they battle-hardened them

i know bugger all about what makes a good motor tbh, so any motor scientists feel free to chime in

[b264]

@glyphiks

Omg. This could so easily be modified into a ballsack

Do it

[superjet700]

What happens if I keep increasing my max motor amps setting in VESC? Is the temperature of the mosfets the only danger? What about motors, if they’re bellow a dangerous temp can max motor amps be further increased?

[b264]

Make sure fault timeout is around 85ms (instead of the default 500ms) so if it cuts out, you probably won’t loose your balance and topple.

[ZachTetra]

Why does the switching on an antispark blow up the gates but the gates on the phase drivers are fine even though they have so much more abuse?

[b264]

@b264

Most “inrush limiter circuits” fail because they are operating in linear mode during inrush. It’s a design limitation on almost every one.

Imagine a FET is a resistor with a variable resistance. When it’s “off” the resistance is [nearly] infinity and when it’s “on” the resistance is [nearly] zero. That’s all fine and dandy until you add capacitors to the load, like the filter capacitors on VESC and other ESCs. Right when it turns on, it’s effectively a momentary short circuit with [not really…] infinite current because the capacitors are empty. So what the antisparks do is they limit inrush current by turning on not from zero to full blast, but gradually over several milliseconds they ramp from [nearly] infinity to [nearly] zero ohms. It’s this period during the ramp that is the problem, the FET itself is taking almost the entire load due to Ohm’s law because the capacitors have effectively zero resistance to inrush. It’s said to be operating in “linear” or analog mode at this point, as opposed to “digital” mode where everything is either on or off with no in-between. This is extremely stressful to the junctions inside the FET and technically exceeding the design limitations for a very brief period of time. Each time it’s powered-on, it’s taking a tiny bit of damage.

The way to ameliorate this is much the same way a loopkey works – you have a “precharge” circuit where the nonzero inrush-limiting resistance is provided by an actual discrete resistor instead of the FET junction itself. So you have one FET with a heatsinked power resistor in series, that is separate from the one or more FETs on the main power switch.

So in order of operation, you’d have a single FET turn fully on [nearly] instantaneously (digitally) with a resistor in series to charge the filter capacitors, then once the output voltage approached the supply voltage (meaning the capacitors are nearing full charge) then the main FET(s) turn on [nearly] instantaneously (digitally) to supply high-current power to the system. This is never operating in “linear” mode but is “fully digital” and will not suffer the incessant failures that plague the inrush-limiting Vedder design. The power limiting and heating is moved to a discrete resistor instead of burning off the energy inside the FET junction itself, which stays cool during inrush.

@ZachTetra

Why does the switching on an antispark blow up the gates but the gates on the phase drivers are fine even though they have so much more abuse?

Because it’s not acting as an inrush limiter. It’s turning on to full blast instantaneously.

[moose]

Hi, I am looking to buy two VESCs to link with two 6355 4kW motors (77 amp max? not sure), and maybe in the future upgrade to 6384 5kW (75 amp max?), and link the VESCs with a can bus connector. What VESCs would you recommend? I’m interested in them being resilient and I want to have confidence they won’t just break on me and break my neck lol.

Thanks in advance!

[That_Jamie_S_Guy]

I had no idea glue lined shrink existed

[glyphiks]

It’s pretty good. Can be a pain to remove, but not extreme

[yoyotinker]

Do stock hypertrucks have 10mm or 12mm axles?

[That_Jamie_S_Guy]

How the hell do I order from Fogstar?

I’ve just received an invoice for 50x Samsung 40T cells and 3x 20 packs of 21700 insulator rings for £200.40

Do I just do a bank transfer to the account details attached? How will they confirm I’ve paid?

[frame]

@That_Jamie_S_Guy

bank transfer

never

[JeffyJ]

What is likely to be the most reliable option…

4wd dual DV6 connected via CAN with one remote/receiver

Or

4wd dual DV6 with split PPM from remote reciever going to both ESCs.

In both cases the cable will need to be about 44 inches.

Thanks all.

[That_Jamie_S_Guy]

What do you mean

[rosco]

It offers no buyer protection

[glyphiks]

There is a small discussion here that’s probably worth reading

Connecting Multiple ESCs: Dos, Donts and Dual Receivers (SERIOUS)

I stole this image off google. [images - 2020-01-30T195620.542] Righto, my first SERIOUS thread don’t let the title fool you, this is not an invitation for a shit fight on redundancy. I will be flagging the shit out of this thread if it strays from pure technical advice. Over the last year, I have done a LOT of reading, and feel pretty confident that I could connect most ESCs together in various ways without blowing anything up. But the information that I have learned on this topic is …

I would 100% go with CAN. Having the ability to use a single bluetooth module for all 4 escs would be the main reason for me.

[JeffyJ]

Yes that is cost effective for sure. After reading through that thread it seems a lot of people go split PPM. Last time i did CAN with 4wd on DV6s it worked fine though so will likely do it again.

[b264]

@glyphiks

I would 100% go with CAN. Having the ability to use a single bluetooth module for all 4 escs would be the main reason for me.

¿Por qué no los dos?

You can actually do that while using PWM control if you want to.

Just saying it’s an option.

[JeffyJ]

So are you saying to still have the ESCs connected over CAN and use split PWM control?

[tech.shit]

yes. I do this currently on my build, but on a smaller scale with only 2 ESCs over CAN and PWM split to both.

it provides sort of a “failover” for if one input has an issue the other one is there to still be connected.

could even go a step further and have 2 receivers connected to the one remote in case a receiver goes.

this is a case where I think redundancy has a place.