jsatan Posted February 23, 2008 Share Posted February 23, 2008 Hi guys, Its been a while and my brain has gne soft, (blows the dust off the chess set). Right, I've got a LED it is a 2.5V at 11mA I've got a battery at 1.5V 1800mA How long would the battery last if the led worked at this low voltage. worked it out and I got some silly number, something like 43 sec's. Can someone show me the way this would be worked out so I know for the future. My cals were: (1.5 * 1.8)/(2.5 * 0.011) That says my led would only last 108s, my maths has gone!!! Jon. Link to comment Share on other sites More sharing options...
swansont Posted February 24, 2008 Share Posted February 24, 2008 Batteries are rated in mAh, i.e. milliamps * hours Link to comment Share on other sites More sharing options...
YT2095 Posted February 24, 2008 Share Posted February 24, 2008 I work it out to 98.18 hours as an Ideal, however without having the LED specs of current by voltage curve, it`s impossible to be 100% accurate. Link to comment Share on other sites More sharing options...
jsatan Posted February 24, 2008 Author Share Posted February 24, 2008 Batteries are rated in mAh, i.e. milliamps * hours oops, thats why My cal are off by a long way. Thanks guys! PS can you show me how this was worked out as I can the numbers close to YT's but I'm out by a factor of 10. (EG 981.81 HR) Link to comment Share on other sites More sharing options...
YT2095 Posted February 24, 2008 Share Posted February 24, 2008 the batt is capable of 2.7Watts for 1 hour the LED draws 0.0275Watts so 2.7 / 0.0275 = 98.18 at least that`s how I worked it out Link to comment Share on other sites More sharing options...
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