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Joined 1 year ago
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Cake day: June 13th, 2023

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  • The problem is that international travel simply doesn't make sense for many Americans. The U.S. only has two international borders - Mexico and Canada. Any other international destination is going to be a flight across an ocean (South America isn't, obviously, but the distances/costs are similar), which can be $400-$1200 per person. The cost/duration of flights and need to adjust to a dramatically different timezone means that it really only makes sense to travel internationally when you can go for at least a week at a time. However, Americans tend to have very limited paid time off - usually only 10-20 days or so per year - and that is often a combined pool for vacation, sick time, etc. This means that a single international trip can chew up over half of the PTO for the entire year. So even if you can afford to travel, you don't have enough time off anyway. Most of the time it makes much more sense to travel domestically and just take Thu/Fri off for a long weekend.

    (This is speaking from experience, if you couldn't tell, lol)


  • Sorry, I basically combined two separate thoughts in a weird way. First, I meant that the raw battery cells themselves are usually rated in mAh on their datasheets, so manufacturers simply kept using that unit on their marketing material. Second, I meant that datasheets usually use mAh because it is a more appropriate unit than Ah for comparing cells of that approximate size. This is somewhat common in engineering documents - you will often see measurements written as 20.0mm instead of 2.0cm (usually because it is more consistent with the rest of the documentation). In this case it’s because many of the Li-Ion cells used in phones will have their charge/discharge ratings in mA, so it makes sense to have the capacities in the corresponding mAh.

    But I do agree, on marketing material it makes much more sense to just write the capacity in Ah (or better, Wh). Using mAh just because it’s a bigger number is plain silly.




  • The vast majority of cell phones use a single-cell Li-Ion battery, so their capacities can be directly compared using mAh. Laptops almost always contain multi-cell Li-Ion batteries, so their capacity cannot be directly compared using mAh (e.g. a 4S battery rated for 2500mAh has more energy than a 3S battery rated for 3000mAh).

    So why don’t we use Wh for phones too? Simply because manufacturers would rather advertise a battery size of five thousand mAh (wow, so much capacity!) instead of 19 Wh.

    The same issue happens with portable USB battery packs - they’re all advertised in mAh even though they use a wide variety of chemistries and cell configurations internally. What manufacturers do is take the total Wh of the pack and convert it back to the equivalent mAh of a single-cell Li-Ion. It’s annoying, and I really wish they would just use Wh directly.




  • The main problem with lithium ion battery fires is that the reaction is self-oxidizing, so you can’t put it out by just smothering it. You actually need to cool them down enough so that they don’t re-ignite. Plus, once they’re damaged, even if you do cool them down enough they’re much more likely to short and re-ignite themselves again anyway.

    Consider the “fire triangle” - fire needs three things: fuel, oxygen, and heat. With, for example, gasoline fires you can take away either oxygen OR heat to extinguish them, but with lithium-ion battery fires you have to take away the heat to extinguish them.