Philip Harrison Posted December 23, 2008 Share Posted December 23, 2008 can some one help me on this,if i have 2x 11.1v lipos 20c i think they are 2000mah will have to check on that at work,which would give me the best flight time in series or par,which would give me the best power, Quote Link to comment Share on other sites More sharing options...
Brian Lambert Posted December 23, 2008 Share Posted December 23, 2008 Well the experts will be along soon I am sure, but series should give greater efficiency as the IR losses will be less, but I bet it will not be that simple Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted December 23, 2008 Share Posted December 23, 2008 Paralleling two identical packs will double the capacity and therefore increase flight time ( over that of a single pack in the same rig ) however volts remain the same and therefore power will remain the same too. Flight time will not simply double however, as weight will have increased etc. Series will double the voltage and therefore current drawn and power produced will also increase, and duration reduce. Of course simply connecting 2 of them in series, on a rig that was setup to use the one only, will almost certainly let out the magic smoke. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted December 23, 2008 Share Posted December 23, 2008 PhilipAs far as the lipos are concerned series or parallel doesn't make any difference to the power available. In series the voltage is doubled, in parallel the current is doubled but the total power output is the same. So it really comes down to your ESC, motor and prop combination as to which configuration best keeps within the 20c (40 amp) battery limit. If you do have a suitable ESC, motor & prop, a series configuration (higher voltage, lower current) is slightly more efficient as the electrical losses are lower but remember it is your airframe that is absorbing all the power so even a slight improvement in that will result in an improvement in overall performance. Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted December 23, 2008 Share Posted December 23, 2008 Not wishing to sound pedantic here Simon, but in parallel the current is NOT doubled - the capacity is. Quote Link to comment Share on other sites More sharing options...
Philip Harrison Posted December 24, 2008 Author Share Posted December 24, 2008 thanks for the reply lads,had a few different answers, Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted December 24, 2008 Share Posted December 24, 2008 Thats normal really...but I think you should be able to decipher the gist of it - all answers are basically saying the same thing really. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted December 24, 2008 Share Posted December 24, 2008 Timbo - forum moderator wrote (seeNot wishing to sound pedantic here Simon, but in parallel the current is NOT doubled - the capacity is. But if you have 2 x 20C 2000mah lipo's then in series the max current you can draw is 40A but if you put them in parallel then they become a 20c 4000 mah pack so 80A max. Quote Link to comment Share on other sites More sharing options...
Former Member Posted December 24, 2008 Share Posted December 24, 2008 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted December 24, 2008 Share Posted December 24, 2008 As Eric says. You said ....Quote... If you have 2 x 20C 2000mah lipo's then in series the max current you can draw is 40A but if you put them in parallel then they become a 20c 4000 mah pack so 80A max"Yes of course they do, but that is my point...the current CAPACITY increases not the current. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted December 24, 2008 Share Posted December 24, 2008 TimboYes, it would have been better if I had said "the current capacity is doubled" but I was trying to show that as far as the batteries are concerned the power (i.e. the rate of doing work) available is the same either way and is actually limited by the cells c rating and the ability of the motor/prop combination to use it. Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted December 24, 2008 Share Posted December 24, 2008 Its fine Simon,,,as I said I am sure the OP gets the idea - lets not drag the thread out over something minor . Quote Link to comment Share on other sites More sharing options...
Philip Harrison Posted December 25, 2008 Author Share Posted December 25, 2008 cheers lads you are a pool of information,so if i put them in series it will give double the 20c to 40 c. Quote Link to comment Share on other sites More sharing options...
Always broke Posted December 25, 2008 Share Posted December 25, 2008 No If you put them in series it will sill only be 20C but twice the voltage.So 2x11.1 in series = 22.2v at 2200ma capacity. 20c is 44A .In series you have done nothing to increase the capacity only the voltage but the amount of power available is twice that of a single pack.volts x amps = watts so 22.2 x 44 = 976 watts . High voltage low current 2x 11.1 in parallel = 11.1v at 4400ma capacity. 20c is 88A . volts x amps = watts so 11.1 x 88 = 976 watts Low voltage High current If the set up you were using was an 11.1 v set up and you were using a 2200 ma pack and you added an identical pack in parallel to it you would get nearly 2 x the flight time ( remembering it is heaver)If the set up you were using was an 11.1 v set up and you were using a 2200 ma pack and you added an identical pack in series you would smoke the system unless you changed the motor or prop or both as you are trying to get the prop to spin faster as the voltage has increased . Remember one of the specs of a motor is RPM per volt.Its Late on Xmas DayGood night. Quote Link to comment Share on other sites More sharing options...
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