If you’ve ever worked with multi-cell rechargeable battery packs, you know that individual cells will eventually become unbalanced. For the pack to work optimally, each cell needs to be analyzed and charged separately – which is why RC-style battery packs have a dedicated balance connector. So if you know it, and we know it, why doesn’t Dyson know it?
This is the question that has inspired me [tinfever] To start work on the FU-Dyson-BMS project. As you can guess from the name, [tinfever] It is believed that Dyson deliberately engineered their V6 and V7 batteries to fail so that the onboard ISL94208 battery management does not use IC’s cell balancing function. What’s worse, once the cells are out of balance at 300 mV, the controller treats the whole pack as a shot and will not allow it to charge anymore.
Or at least, that’s what used to happen. With replacement firmware [tinfever] Developed, the pack’s battery management system (BMS) will ignore unbalanced cells so you can continue to use the pack (albeit a reduced capacity). Of course the ideal solution is to enable cell balancing in ISL94208, but unfortunately Dyson did not include the necessary resistors in the PCB. Although it is worth noting previous versions of the board Did There are uninhabited spots for them, giving some credibility to the idea that their omission was intentional on Dyson’s part.
But not everyone is involved in conspiracy theories. In the EEVBlog forum, some users have noted that a poorly implemented cell balancing routine can be more problematic than not having one. It is possible that Dyson had some bad experience with the technology in previous packs, and decided to move away from it and try to compensate by using high-quality cells. That said, at least one person in the thread has been able to revive their own “dead” battery pack by installing this unofficial firmware, so whether intentionally or not, there seems to be little controversy that usable batteries are actually being identified as prematurely defective.
Proper cell balance is key even in DIY projects, so we have to agree that it seems somewhat unusual that Dyson would intentionally lock this important feature in their packs. But the jury is still out on whether Sir James is trying to give his clients a quick pull – as Hanlon’s Razor put it, “never blame hatred that is adequately explained by stupidity”.