Smart Buyer: power bank, mAh vs Wh
mAh is counted at 3.7 V: 10,000 mAh = 37 Wh; after the 5 V boost about 6,000 mAh reach the cable (rated capacity).
Your power bank says 10,000 mAh. Does your phone get all of it? 🔋🤔
1️⃣ COUNTED AT 3.7 V: the mAh on the box is counted at the battery cells' 3.7 V. The real energy is watt-hours: 10,000 mAh × 3.7 V ÷ 1000 = 37 Wh.
2️⃣ SOME IS LOST: USB needs 5 V, so a boost chip raises 3.7 V to 5 V and turns some energy into heat. About 30 Wh reach the cable — that's about 6,000 mAh at 5 V. The back of the box calls it "rated capacity".
3️⃣ BUY SMART:
✅ Wh printed on the label
✅ rated capacity (about 6,000 mAh for a 10,000 mAh bank)
✅ output watts that match your phone (e.g. 20 W)
❌ a huge mAh at a tiny price
📌 Watt-hours never lie.
Read the voiceover (transcript)
- Ten thousand milliamp hours. All yours?
- No! They're counted at three point seven volts: thirty-seven watt-hours.
- Boosting to five volts wastes some as heat. About six thousand milliamp hours reach the cable.
- So check the watt-hours and rated capacity, and match the output watts to your phone.
- Watt-hours never lie!
- Next: LED bulbs! Follow for more!
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