Comment on Is there any 5000 mAh power bank with 30W?

mononomi@feddit.nl ⁨9⁩ ⁨months⁩ ago

• ironhydroxide@sh.itjust.works ⁨9⁩ ⁨months⁩ ago

  It’s because you can get more when measuring in mA than you can in A.

  5000 mAh means you can get 5000 hours out when pulling at 1mA. 5 Ah means you can get 5 hours when pulling at 1A.

  You’d think these are commutative, but battery chemistry doesn’t work that way. The harder you load, the less actual power you can get. So a battery that can provide 1mA for 5000 can’t necessarily provide 1A for 5 hours.

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  • mononomi@feddit.nl ⁨9⁩ ⁨months⁩ ago

    Damn, interesting! And that chemist sounding name sure does add extra credibility

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    • ironhydroxide@sh.itjust.works ⁨9⁩ ⁨months⁩ ago

      Don’t read too much into that.

      My chemistry is rust(y).

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  • astrsk@kbin.social ⁨9⁩ ⁨months⁩ ago

    And not to mention the discharge efficiency curve. For LiPo batteries you will see a sort of “coasting” when the battery is at about 3.7v if your load is sufficiently small. But when it’s at 4.0v it will seem to drain quicker.

    I have a 10000mAh battery powering a device that uses 10uA every 30 minutes for about 10 seconds. On one charge it should last about 1 year maybe a little more. The first 2 months it seemed like it lost a lot more juice than was expected but since then it settled in and is now ahead of its estimate. Which means it will speed back up as it goes down below 3.7v.

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    • pearsaltchocolatebar@discuss.online ⁨9⁩ ⁨months⁩ ago

      This is why the nominal voltage of lithium batteries is 3.7v, even though you charge them to 4.2v.

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