Comment on Why is amperage more "obscure" than voltage (or watts)?
Decq@lemmy.world 3 days ago
Many batteries these days are rated in Ah, so that’s something.
One reason is because most power supplies are voltage supplies and not current supplies. Though they do report the max current they can supply. Also voltage is in those cases is (arguably) more important. The wrong voltage and it probably won’t work at all or even breaks. Whereas to little current, it probably still does something, though at reduced power or it cuts off at some point.
Iconoclast@feddit.uk 3 days ago
Ah, or mAh might be a little confusing though - two different batteries can have the same Ah rating but wildly different capacities.
I always convert everything to watt-hours by multiplying ampere-hours by voltage.
Decq@lemmy.world 3 days ago
It is confusing, but it is what they do. I’m not sure why they do it. Probably marketing reasons, seeing as a lot of people think bigger number == bigger better. Of course if you know the nominal voltage of the battery pack it’s not a big issue. But yeah Wh or Joule would be better.
jdnewmil@lemmy.ca 3 days ago
Batteries have both electron capacity (cumulative) and current capacity (rate) ratings. The chemistry and size determine how many electrons (aka Amperes times hours) can be stored, and the conductor sizes (including within the cells) determine how quickly it can be charged or discharged in sustained operation (without permanent damage).
A car battery can be shorted with a screwdriver and discharged at a high current, but only for a short time without damage to the cells. A 100Ah car battery can supply rated current for roughly twice as long as a 50Ah battery.
Sometimes people call these ratings energy and power ratings by multiplying each by rated voltage, but the voltage does vary with charge state and rate of current flow so those “ratings” are rather approximate.