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Comment by matthew-wegner | Hacker News Reader

This sounds bi-directional, though (as in you could run some software with a payload that overloads/overheats your battery).

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Which is non-threatening for the inverse reason; somebody who owns my OS can probably damage my hardware if they want to. Ruining the SSD in my Air would mean a replacement just as surely as trashing the battery, and would be a lot easier.

Now in fairness, being able to make something in my computer start a fire is on a way different level. But we're getting that from "Miller said that it might even be possible to overload the battery so that it catches fire"— he hasn't done it, and doesn't even know if it's possible. My money is on there are some lower-level safeguards to prevent bugs in the firmware from causing fires, even if they do ruin the battery. Li-ion batteries are designed physically with the knowledge that they're a ticking timebomb waiting to go off, and I can't believe that nobody at Apple has started from asking "But what if I were actually trying to make it explode."

Indeed, according to the article, it could be bidirectional:

>Using that password, Miller said that he has been able to do almost anything from giving false readings to the charger and the OS to ruin the device, to completely rewriting the firmware.

I don't know if it would be possible to make the battery burst into flame or explode. After the Sony battery fiasco, I'd expect there to be some kind of hardware interlock preventing short-circuits. However, it is possible to overwrite the battery firmware to prevent the battery from being charged, thus turning your Macbook Pro into a very small form-factor desktop.

Actually, Macbooks use lithium polymer batteries which are highly explosive when overcharged (http://www.youtube.com/watch?v=0MiM2E6pvfg). So by telling the OS that a battery is not charged when it really is can cause it to explode.

That's a bare LiPo cell wired directly to current— not a good demonstration of how a well-designed battery pack would behave, even one with malicious firmware.

I had an internship at a company that made lithium battery packs. The control boards on the packs have primary cell protection provided by a specialized micro controller that monitors cell voltages and prevents over/under charge levels and monitors current, however they also have secondary protection ICs that are hardware based that will shut down the pack should the cells reach dangerously high levels, as well as fuses to prevent dangerous levels of current.

Net result, changing battery firmware can reduce usefulness of battery (higher charging degrades cell life, blow fuses etc) but the packs should have hardware based protection from being a safety hazard

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