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Dyson v7 Trigger cordless vacuum - TEARDOWN of battery pack

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--- Quote from: deuteron on May 31, 2023, 08:30:09 pm ---Hello All,
the electronic load, which I've ordered, arrived today. Tomorrow I'll do the first capacity measurement with the Dyson SV10 battery pack. Just one additional question, because I'll try not to brick the pack:
Is there any minimum output voltage, which may cause the BMS to lock when fallen below ? Otherwise I would try 15 V discharge minimum being 5 x 3V. Surely I will measure all the cell voltages individually through the discharge process, in order not to get too much of an unbalance. If somebody knows, please let me know

--- End quote ---

The vacuum normally runs until the BMS turns off the output when the voltage goes too low, so it doesn't matter what you set. Assuming you are leaving the BMS in the loop and not discharging the cells directly.

just if someone is interested: I tested the capacity (at 3A) of the SV10 battery pack, about which the preowner told me that it is not as good as in the beginning. As said, cell balance was pretty good, max charging voltage ~4.1V in average. The meassurement (3.0V cut off on the weekest cell) resulted in a little bit more than 2000mAh. The pack is marked with 2800mAh on the casing. Ok, looks like some wear of the cells. But, the interesting thing is the following: I also own a (red blinking) SV10 pack gotten together with another V8. Since I didn't plan to reprogram it, I just took it apart th salvage the cells. These cells appear to be LG ones (LGDAHD2C1865) with a max current of 22A, so well suited for the Dysons consuming around 20A max. I googled for these cells and found the data sheet. The cells have a capacity rating of only 2100mAh even though 2800mAh is explicitly written on the casing of the pack ! This agrees well with my measurement and shows that the pack is practically like new, although used for more than one year.
In principle this is just another story about wrongly declared batteries from China. The interesting point here is that even Dyson itself doesn't seem to care about. I personly will stick to the power tool battery solution which is astonishingly working well even though the packs are only 18V.


--- Quote from: dvd4me on February 16, 2022, 03:54:11 am ---
--- Quote from: tinfever on February 16, 2022, 12:03:19 am ---

Looking that the settings options further, I see there are checkboxes for "Preserve Program Memory" and "Preserve ID Memory" that sound like could have prevented this. In hindsight I should have tested altering the EEPROM while leaving protected code untouched on my SV11(V7) BMS I've been programming first to make sure my settings were correct.

--- End quote ---

Hello tinfever, amazing job you did, on the good side your hard work it brings things closer and closer. I am pleasantly surprised you found the lockout algorithm, others can benefit and fix the balancing before putting the pack to charge.
It really sucks the MPLAB IPE settings are not very clear and there is only one chance of doing this, since the PIC accepts a full erase with no problem but no reading...
I hope the batteries you bought used are not the clones, those seems to last even shorter due to bad cells.

I know that being stubborn to find the solution, most of times pays off, as a sidetrack I just finished fixing a dead HP Pavilion 23xi display monitor found many months ago that was behaving strange... No wonder it was thrown away, other seems to have similar issues with this model. I bought the main chip and change-it, reprogram the Winbond 25x4 serial flash chip, changed the oscillator crystal... the monitor was not booting up... Just playing dead. I start to look around the resistors connected to the Winbond chip, one was bad, a 10k one was just open and the pin 7 - HOLD, the pin was floating low, chip was always going on HOLD because of that, no data,  so much work just for a stupid resistor... R54, circled. I leave this here in case someone googles for this issue on the HP 23xi series.
I took this work as a chance to practice my fine pitch soldering and the serial flash chip reprogramming, it was a while since I had not done this. I put the picture just for show off, my fine pitch manual soldering skills...  ^-^

Back to our subject, I hope you will receive your batteries soon to test the settings for lock bit re-programming. Meanwhile can you just load some garbage into the pic program area, set the read protect bit and then try to alter the eerom map and see if the program data is getting intact?
Since your chip is still working please try to find the exact settings of the MPLAb IPE so I will not erase mine when I will try to restore the lock bit.


--- End quote ---

hi dvd4me - on your video someone posted they had modified the eeprom locations using IPE software (and pickit4 ?)  I am afraid to try and have succeeded using the standalone however I just spotted this option - is this Erase All setting not perhaps the problem?


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