The lhs guy is correct.
The "mah" capacity is directly responsible for runtime. It is like "gallons" of fuel.
For the voltages: Per cell. 3.5-3.7 is considered "empty" Here's two charts.
<colgroup><col width="86" /></colgroup> | 3.7=0% |
| 3.8=20 |
| 3.9=40 |
| 4.0=60 |
| 4.1=80 |
| 4.2=100% |
<colgroup><col width="86" /><col width="86" /><col width="86" /></colgroup> | 100.00% | | 4.2 |
| 90 | | 4.13 |
| 80 | | 4.06 |
| 70 | | 3.99 |
| 60 | | 3.92 |
| 50 | | 3.85 |
| 40 | | 3.78 |
| 30 | | 3.71 |
| 20 | | 3.64 |
| 10 | | 3.57 |
| 0.00% | | 3.5 |