Battery capacity: Difference between revisions
Jump to navigation
Jump to search
no edit summary
m (moved Measures of Capacity to Battery capacity: better description) |
No edit summary |
||
| Line 13: | Line 13: | ||
There is more to a good battery than its measured capacity. An LED might draw 1 amp of current at 3 volts. So that is 3 watts or 3000 milliwatts. If you have a 2400 milliwatt-hour NiMH battery (whose 1.2 volts of power are being boosted to 3 volts to run the LED) then you can figure that you could run the LED for 2400mW*hr/3000mW=0.8 hours, or 48 minutes. But you're having to provide a lot of current (I=P/E) of 3/1.2=2.5 amps. That's a lot for any battery to deliver and it will at least get very hot and may only be able to drive the LED at something less than 3 watts. So the ability of a battery to deliver a high current is also important. "High drain" devices require more current. | There is more to a good battery than its measured capacity. An LED might draw 1 amp of current at 3 volts. So that is 3 watts or 3000 milliwatts. If you have a 2400 milliwatt-hour NiMH battery (whose 1.2 volts of power are being boosted to 3 volts to run the LED) then you can figure that you could run the LED for 2400mW*hr/3000mW=0.8 hours, or 48 minutes. But you're having to provide a lot of current (I=P/E) of 3/1.2=2.5 amps. That's a lot for any battery to deliver and it will at least get very hot and may only be able to drive the LED at something less than 3 watts. So the ability of a battery to deliver a high current is also important. "High drain" devices require more current. | ||
Cells that have high internal resistance will not be able to deliver the same current as ones that have less internal resistance. Alkaline batteries have higher internal resistance than NiMH batteries | Cells that have high internal resistance will not be able to deliver the same current as ones that have less internal resistance. Alkaline batteries have higher internal resistance than NiMH batteries. | ||