this post was submitted on 02 Apr 2025
87 points (94.8% liked)
Technology
69346 readers
2813 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related news or articles.
- Be excellent to each other!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, this includes using AI responses and summaries. To ask if your bot can be added please contact a mod.
- Check for duplicates before posting, duplicates may be removed
- Accounts 7 days and younger will have their posts automatically removed.
Approved Bots
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Powerbanks are where it's most problematic. They're usually reporting the capacity of the battery cells in mAh. Those cells will be at 2.8-4.2V during operation, but the powerbank outputs 5V, or in modern powerbanks some higher number. 5000 mAh at the 3.6V average of the cells during discharge is certainly not 5000 mAh at the 9V it's giving to my phone.
It's not going to give my phone 2000 mAh @ 9V or 18 Wh as the math would suggest either because it's well below 100% efficient. I'm not sure what's reasonable to demand in terms of advertising here since efficiency will vary with output voltage and output wattage.
Ideally they would provide a graph showing how many watt hours it will output from minimum to maximum load. If it supports multiple voltages, there should be a separate line in the graph for each voltage.