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Dyson v7 Trigger cordless vacuum - TEARDOWN of battery pack
tude888:
Thank you for getting back to me so quickly.
The BMS boards I was able to find are simple: the charging and output ports are the same. two wires (see attached).
My (very crude) solution is to connect the BMS directly to the charging port, and insert the trigger switch between the BMS and the vacuum motor. The problem with this solution is that the user will be able to turn on the vacuum while it's charging. I don't think this could cause any major problems unless I'm missing something.
Sadly the vacuum charging plug has only two pins. If it had three, I could probably wire it so it would cut off the motor when plugging in the charger.
The other alternative would be to put together a simple circuit, maybe 3 - 4 transistors to cut off the load when the charger is plugged in. I'll put together a schematic, but first I want to test the BMS idea.
Will keep you all posted.
KalleMp:
--- Quote from: tinfever on August 18, 2022, 09:53:00 pm ---My firmware doesn't lock you out if the cells are far out of balance. However, it will shutdown with those 3 blue blinks if any battery cell goes too low. Of course, it can only charge the battery pack until the highest cell hits 4.2V, and only discharge the pack until the lowest cell hits 3.0V, so if the pack it out of balance, you'll get diminished usable battery capacity.
--- End quote ---
I wonder if you might like to save the time, cell voltages and temperature every time the trigger is activated and released, same for charger insertion. It might give ideas on how the batteries behave and give warning of failing ESR. I would be happy to sacrifice the bytes of EEPROM and the wear will likely never become a problem. It could be used to snapshot the values when charging by pressing the trigger or plugging in the charger while doing load tests and then reading the data. Using IR-Da or RC5 codes could get data out without opening the case perhaps.
Your project has been phenomenal and just keeps on giving now that it supports V8 with just funny lighting effects.
KalleMp:
--- Quote from: tude888 on November 15, 2022, 10:34:10 pm ---- Second question: would it make sense to replace the original BMS with a cheap 6s BMS module that does the balancing on its own? (i know some functionality would be lost, but it seems the simplest solution)
--- End quote ---
The Dyson board also manages the power switching, a lot of amps and using a switch would need a beefy switch. Also there is not much space to add a second board. Connecting to each cell and leaving a multi-pin balancing charger connection on the outside is probably the easiest. A possibly simpler balance capable board could be made that simply turns on the output when you press the switch but you would loose a number of protection modes. Making a board that includes balancing support but is otherwise the same is also possible but might be more money than it is worth.
What is a cunning idea though is to do the design and order some boards etched, perhaps even a few prototypes populated at a service in the east, add the GitHub repo name to the silkscreen layer that includes the Hex File and BOM and some eastern knock-off shop will start making the boards at a price we could only dream of achieving, soon to be sold on Amazon and then callously ripped off by Amazon and sold under their own brand.
This may be the correct way to make open-source-hardware affordable. Design and let it get copied in the east. Instead of bemoaning the rip-off, expect and embrace it.
tinfever:
--- Quote from: KalleMp on December 03, 2022, 08:16:14 pm ---
--- Quote from: tude888 on November 15, 2022, 10:34:10 pm ---- Second question: would it make sense to replace the original BMS with a cheap 6s BMS module that does the balancing on its own? (i know some functionality would be lost, but it seems the simplest solution)
--- End quote ---
The Dyson board also manages the power switching, a lot of amps and using a switch would need a beefy switch. Also there is not much space to add a second board. Connecting to each cell and leaving a multi-pin balancing charger connection on the outside is probably the easiest. A possibly simpler balance capable board could be made that simply turns on the output when you press the switch but you would loose a number of protection modes. Making a board that includes balancing support but is otherwise the same is also possible but might be more money than it is worth.
What is a cunning idea though is to do the design and order some boards etched, perhaps even a few prototypes populated at a service in the east, add the GitHub repo name to the silkscreen layer that includes the Hex File and BOM and some eastern knock-off shop will start making the boards at a price we could only dream of achieving, soon to be sold on Amazon and then callously ripped off by Amazon and sold under their own brand.
This may be the correct way to make open-source-hardware affordable. Design and let it get copied in the east. Instead of bemoaning the rip-off, expect and embrace it.
--- End quote ---
Apparently there is a Russian firmware version (not open source) that actually sends debug info out over the LED like you mention. It's a really cool idea. Now that I think about it, ideally you'd be able to have your smartphone camera decode it with no outside electronics required!
Although if the phone camera is limited to 60 fps, that might limit you to 60 bits per second of data absolute max if you only use on or off. I wonder how much data you could encode in the colors of the LED?
This is kind of insane but this paper makes it sound like the researchers managed to transmit 47 Kbps! It sounds like they are using a single RGB LED but I can't tell how they are getting 264 symbols/frame with a single LED.
"47 kbit/s (264 symbol/frame × 3 bit/symbol × 60 frame/second)"
https://opg.optica.org/oe/fulltext.cfm?uri=oe-27-23-33840&id=422856
it be clear, the odds I actually implement anything like this are pretty much zero. It'd be really cool but unfortunately being cool doesn't pay the rent :(
SilverSolder:
--- Quote from: tinfever on December 05, 2022, 02:09:49 am ---[...]It'd be really cool but unfortunately being cool doesn't pay the rent :(
--- End quote ---
Being cool is much more important than paying the rent, though, so some kind of compromise needs to be achieved! :D
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