Dyson V6 SV09 BMS replace and reviving laptop batteries while in deep sleep mode - Page 1
Forum section: electronics / general

author: dvd4me
author_rank: Regular Contributor
timestamp: January 13, 2022, 02:25:33 am
content: Hello,I did a replacement of the faulty Dyson BMS in a red light error condition, for a V6 battery, you can see-it here:https://www.eevblog.com/forum/reviews/dyson-v7-trigger-cordless-vacuum-teardown-of-battery-pack/msg3936373/#msg3936373While reading the datasheet and posts about the ISL94208 battery management IC in the Dyson packs ( some are having different IC's) I came upon a term "BMS sleep mode" referring to a deep sleep state of the controller Ic, in order to reduce the draining on the battery while not in use.Then it just hit me the idea of assuming almost all the batteries that are discharged to a certain level, they go into deep sleep mode, where the BMS main IC disconnects himself until it's wake up by external conditions.Well, those conditions are powering up to charge, right?So I recently found 2 really old laptops that still had the battery left in, this is great to test my presumption!I gently drilled 2 holes with a manual drill as seen in the picture, in the opposite ends of the battery. Most battery never have any electronics there, only the thin nickel connection plate.I measured the voltage and was around 2.6V per cell, assuming the cells were still equally discharged.2.6V is a sure BMS lock when you try to plug the laptop and battery in the charger! Well, these 2 laptops seems like they have never seen a charger before they died happily.On the asus one I was able to rip the black label and have access to each cell, to confirm the cells were pretty well balanced at 2.6V.I charged both packs, thru the holes on the sides to a minimum 3.6V per cell, 3S = 11V, 4S 14.4VI started with the ASUS one, inserted back into the laptop and plug in the charger. To my complete surprise it started to charge as nothing ever happened. It charged completely up to around 4V.I am not sure how much capacity that battery has but it's safe to assume it's low, a cell under 3V for so long it's decreased in capacity.Still in disbelief, I inserted the HP one in the laptop ( a laptop that was not even powering on, one of those DV9000 duds, but still charging) and again the miracle was there, it started to charge!Same thing, on this one I assume the cells were decently balanced, since I was too lazy to try to get access to the cells to verify.The charging stopped at 4V per cell, quite good. I will see in couple of weeks if they will actually hold the charge and are not going into higher self discharge state.The idea of this test is that if you ever want to reuse an older and long time sitting around battery, never plug the laptop/appliance charging first, to activate the BMS and officially kill the battery.Check the voltage and if it's just under 3V it may still be good to revive-it. Dyson V6 original BMS discharges cells until 3.1V, so it's safe for the battery chemistry to go that low.I will test more battery to try to replicate this, in case the BMS lock was not triggered by the low cell voltage and are still in deep sleep mode.This can be useful to try to re-cell the BMS while in deep sleep, maybe it can be done without wake-it up.Regards

author: dvd4me
author_rank: Regular Contributor
timestamp: January 31, 2022, 04:50:47 am
content: Hello again,Just happen to try another battery with low voltage, hope to be in deep sleep mode, never to be awaken in low voltage before.I wished I knew this before, so many times I came across this situation that I found a battery that I did not knew the status and just plugged in for charging, not knowing that I have to check first the voltage, before even try to charge-it. Often battery that sits in a laptop for a very long time it gets into low voltage deep sleep mode.The moment you plug-it in it blinks couple of times and then gets the error mode...For example a laptop that sits aside for very long time take off the battery. While in, it seems that it's continuing to slowly discharge, even in deep sleep. Not sure why.Most battery still presents voltage on the terminals if the discharge state is not below the cut off voltage.Voltage on the + and - pins (usually the pins on the sides) means it's ok. It may be unblanced but it's not BMS locked.Once you have a battery with no voltage on the connector pins then you should check the charge to see how low it is. Some battery have to be in the laptop to be enabled, more rare.The one in the picture was 5.5 V, can you figure that out? Would this have any chance to "normal charging" ? I surely do not believe so.Then I bring-it to a minimum 3.7 V per cell and finally plugged in to charge.The first couple of seconds are breathtaking, since the BMS status is unknown... To my relief, the charging light it was getting orange, as you can see in the last picture. I was using an extender for the charging connector, to measure the voltages. Also it's useful to use the extension for other types of battery, same brand but different positioning of the connector, while having just one laptop to " charge"

author: dvd4me
author_rank: Regular Contributor
timestamp: February 17, 2022, 04:05:12 am
content: Hello again,On the same - deep sleep - mode I came back with another example. This is a more recent laptop, HP Elitebook 840 G2.Battery status was unknown so I did NOT plugged in for charging since that is exactly was locks them out.Carefully open the bottom side so it will not look bad after and measured the voltage, almost 8V / 3 = 2.6V, quite low, assuming BMS is in sleep mode.Since I had no direct access to the cells terminals I improvised, a resistor inserted for the negative and a heavy magnet to sit on the positive.Manually charged the cells until they reached 3.7V per cell and then put the battery pack back in the laptop and... tadaaa.. it's charging.I put the extender so you can see it's the same opened battery and the orange charging light will lit.If I want to use the laptop for something then I have to find the bottom lid, the idiots discarding this laptop, they threw the cover somewhere else.Curious to see how much capacity the battery has left. Otherwise it's not worth to try to find the back cover and a new battery, a new battery like this is $40-50, crazy money and the back cover $30 _ made of goldThat's why reviving the battery makes the whole difference into saving the laptop or not, since they are so expensive.Cheers

author: dvd4me
author_rank: Regular Contributor
timestamp: February 20, 2022, 03:21:14 am
content: Hello again,I just landed on a page about laptop battery fixing, specifically resetting the Permanent Fail flag, via special software that "unseal" the access to the battery manager chip - bq3050 and similar series, giving full control over it.The master password on those chips was uncovered some years ago by a DefCon genius dude. Since then, couple of years ago, a special software was developed to access the SM bus and communicate with the battery.Imagine unlocking a couple of batteries that were very low discharged, under 2.8 - 2.9V per cell. A computer shop can save hundreds using that software.Well, I do not have that much money to buy this kind of software and play with it, even if it looks like it's very interesting.What I have found it's sort of a hardware trick that's based on the power saving mode of those bq3050 series controllers, which is they basically fall asleep and then you can do pretty much a lot with the cells while he's asleep.Manually charging and balancing the cells and then wake up the controller, this has high chances of rendering the battery still usable, if the PF flag was not previously set by trying to charge a very low discharged battery.It does has the disadvantage that you have to access the battery terminals, sometimes a bit more complex than drilling the holes on the sides.And if the PF flag is set, there is nothing that can be done, without the respective software to reset-it.