PatMc Posted June 28, 2017 Share Posted June 28, 2017 Martin, power requirement isn't what we're looking at, we're considering energy requirement, which is identical whatever the applied voltage. The current is determined by Ohms Law, albeit for different periods of time. Because the energy is the same the ratio differences of currents & times cancel each other out to give identical Amp Hour consumption. But as said quiescent current will increase. Bottom line - looking for an explanation for the observed phenomenon in the above is a red herring. The differences between the self discharge & recharge regime of lithium & nickel batteries is the most likely explanation. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted June 28, 2017 Share Posted June 28, 2017 Posted by PatMc on 28/06/2017 17:31:21: Martin, power requirement isn't what we're looking at, we're considering energy requirement, which is identical whatever the applied voltage. Wasn't that what I said originally? We're just dancing around the same point and getting bogged down by terminology. I think this started when you confused current with ampere hours but in essence, we're agreed over the fact that there is a significant difference in charging efficiencies. My original intention was to try to offer a possible explanation for the perception that less energy is taken from a LiFe than a NiXX battery - and I think that a consensus has been reached for at least a major part of the answer. I may not have explained my original theory very well - but it comes back to energy density which I think we both agree on. Quote Link to comment Share on other sites More sharing options...
Mike Blandford Posted June 28, 2017 Share Posted June 28, 2017 I note several references to using ohm's law regarding servos, as though they a simple resistances. As they have motors in them, they are inductive, as well as being motors. The inductance means as soon as a voltage is applied to the motor it immediately generates an opposing voltage, which then decays over time, allowing the current to increase. In adition, as soon as the motor starts to rotate, it acts as a dynamo and also generates a voltage that opposes the applied voltage. The mechanical power out from the motor is this "dynamo" voltage multiplied by the current flowing (less any mechanical losses). These mean that the actual servo response is very complicated. Mike. Quote Link to comment Share on other sites More sharing options...
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