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A New Smart Antispark (more fireworks?)

Since I keep running my mouth off on other antispark threads, thought I would make my own.

Starting a discussion on this before I roll out prototypes.

Features

  • HIGH SIDE SWITCHING << VERY IMPORTANT, NO MORE CANBUS FIRES.
  • In-rush current limiting as specified in the ltc7004 datasheet, dV/dt is ~184V/s
  • LTC7004/7001 means driving N-Channel MOSFETs.
  • 12S operation, swapping the ltc7004 for the ltc7001 and the MOSFETs means 20S operation (there will be an ESC that supports 20S, in time :wink: ).
  • Roll-to-start, works at low speeds, but will also trigger if you give the board a good enough bump
  • Auto-turn-off, detects changes in current through a proprietary algorithm, if no change for 20 minutes, turns off. This also means if you decide to coast for 20 minutes, or apply a constant throttle for 20 minutes, it will also turn off. There is a 10 second delay after it turns off.
  • With a heatsink, it will be able to handle 100A continuous without issues.
  • OPTIONAL Momentary Pushbutton, 0.3s to turn off, 1s to turn off, holding it down will cycle it on, then off.
  • Easily reprogrammable attiny85. Firmware updates or installing custom firmware is as easy as bodge wiring an arduino uno to the programming pins.
  • Production version will be 30x30mm.
  • Very low quiescent current draw, more details on this below.

LIMITATIONS

  • Maximum output capacitance of 6,000uF. Beyond this, auto-turn-off gets finnicky, beyond 10,000uF, the MOSFET popcorns.
  • NO HOT SWAPPING (this is true of ALL antisparks) when installing, plug in the ESCs first, then plug in the battery, and do the exact reverse when uninstalling (unplug from battery first, wait for ESCs to turn off, unplug ESCs) Try to make sure everything is off when uninstalling.
  • No short-circuit protection. This is what a fuse is for. If this device attempted to do that, both the MOSFETs and the gate driver will popcorn from the negative transient.
  • Auto-turn-off will not work with messed up ESCs, like some of mine are, namely they get hot for no reason while idling, no clue how they still work on 10S FOC.

Other Details

  • There will be two versions made by two different manufacturers. One version will use an LDO to supply the logic circuitry, this one will be low cost. Quiescent current draw is 100uA at all voltages. The second version will use a buck converter to generate the logic rail, quiescent current draw will be ~20-40uA. The second version will be more expensive. Buck converters are not cheap.
    To put this in perspective, 100uA will drain a 200mAh capacity in just over three months. For me, this is fine, for others, they’re going to want the micropower version.

  • The LDO version, a trusted forum member is testing my one and only hand assembled prototype, and I have an OEM prototype. Testing should conclude within the next couple of weeks. I may be able to send the OEM prototype for further testing to another trusted member.

  • There were five, but now there are three low power prototypes that will be hand assembled, I will be testing one myself, and sending the others to trusted members for testing. I may order up parts to make another five. I am currently resolving issues with the power supply circuit as my dumbass joshineered the buck converter and neglected to include ripple injection that the datasheet clearly mentioned was required.

19 Likes

I like your strategy of a less expensive, higher current version. That is totally fine for active riders as it is easy to disconnect batteries in the off season (if any). Definitely rooting for you!

1 Like

Will you make smaller or larger versions? I would love an actual antispark switch on my dual 80100 board, but 100a would never be enough. I would love to see someone competent make a 200a+ antispark.

I am not gentle with my mtb’s. They are current hungry beasts for what i use. Right now, i use multiple xt90 loop keys in a single 3d printed case. It works, but its annoying

I’ll talk to the manufacturers to see if they are willing to produce a larger version with more MOSFETs in parallel.

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Youre my new favorite person.

Community created products are always so much better imo. It supports the small guy, and i give direct feedback that you actually care about unlike a big corp.

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UPDATE:

So I got off my lazy ass and made the attiny85 firmware not garbage and now the quiescent current consumption is down from 3mA to 80uA
That’s MICRO amperes.

This means the LDO regulator version will last three months on a 200mAh charge. The micropower version will last YEARS.

I ran into issues with the micropower version. I fixed the ripple injection circuit, but the buck converter is injecting too much ripple into the power supply rail. I will need to add an additional linear regulator or voltage reference between the buck output and attiny85 supply.
This means pcb respins, ugh.

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What sort of price are you thinking for these?

Something in the $40-$60 range
12s 200A, high side, smart.

Can’t make any promises though.

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If thats the price, i will be taking a few lol.

Is there some visual indicator that the switch is “on”?

This is kinda out there, but do you think it’d be interesting to add a beeper to indicate when auto shutdown is imminent? Maybe a series of different tones… Given you have the mcu and all.

The led on the pushbutton will indicate the state of the switch.

I can add a beeper, it will be more expensive.
And honestly, I do not think it is worth the additional cost.

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Any news on the development of the switches @Gamer43 ?

The manufacturer is currently testing maximum current limits.

I am working on a second design for a different one, finalizing the PCBs for that one.

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What sort of eta are you expecting for it?

I honestly have no clue, sorry.

I’m am hoping it is by the end of this month.

2 Likes