David Martin 2 Posted December 18, 2007 Share Posted December 18, 2007 Can anyone elighten me as to the performance difference on FP micros (like the Piccolo/Hummingbird etc) of swapping the normal 7 cell 8.4v Nimh pack for a 2 cell Lipo..?I was wondering whether the lower average output voltage of the Lipo pack would fly the model ok for an appreciable time..? They are lighter.Some time back, Perkins offered an upgrade Li-ion 10.8v pack as an alternative but they didn't seem to catch on. 3 cell Lipo packs (11.1v) burn out tail motors very quickly and stress the electronics, but what about 2 cells...? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted December 18, 2007 Share Posted December 18, 2007 In nominal voltage a 7 cell nickel pack is 8.4v ( 7 X 1.2v ) and the 2s Lipo ( assuming a reasonable capacity to hold voltage under load ) is 7.4v ( 2 X 3.7v )However, the lighter weight of the Lipo should more than compensate for this slightly lower v. Quote Link to comment Share on other sites More sharing options...
David Martin 2 Posted December 18, 2007 Author Share Posted December 18, 2007 Thanks Timbo.I'll just have to dip in the tin and try one I think, I've not heard of others transferring over though for some reason. Quote Link to comment Share on other sites More sharing options...
Brian Daniels Posted December 19, 2007 Share Posted December 19, 2007 I use a 2 cell li-po on my FP and it seems to fly ok, i did go for a high capasity that makes the pack a little on the heavy side but still flys ok. Quote Link to comment Share on other sites More sharing options...
David Martin 2 Posted December 20, 2007 Author Share Posted December 20, 2007 Thanks Brian, I was asked to trim someones E-Sky FP heli out for them the other day and that flew very well on the supplied 2 cell 1000mah Lipos. Very similar design to the Piccolo and Hummingbird FP range.We did find though that it had to be positioned a lot further forward than the Nimh packs to keep the c of g right, (being a lot lighter). I don't know whether I'd get the Hughes canopy back on my Piccolo without needing to carry extra ballast to balance with the Lipo seated where the Nimh pack goes. I'll have a go.Cheers. Quote Link to comment Share on other sites More sharing options...
winchweight Posted December 20, 2007 Share Posted December 20, 2007 I fly my Piccolo on a 2 cell LiPo. no dramas, as its much lighter than the NiCd pack. Be warned that you probably don't have any under voltage protection for the LiPo, so don't over discharge it (ask how I learnt that). Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted December 20, 2007 Share Posted December 20, 2007 How did you learn that ? Quote Link to comment Share on other sites More sharing options...
Brian Daniels Posted December 20, 2007 Share Posted December 20, 2007 BoomBoom very quick.. When mounting my lipo i had it at 90 degrees so the connectors were pointing out the side that way i could get it just that little bit closer the front of the model. As for over discharging i timed a flight and stoped the clock as soon as i detect a drop in power, i then checked how much charge went back in to the pack, I then tweeked the length of flights to i was within the 30% lipo rule Quote Link to comment Share on other sites More sharing options...
Owen Hailey Posted December 26, 2007 Share Posted December 26, 2007 Hi davidI find my lipo's on ebay from H K at a price that I can aford, and as for fast charging and rliability these are fine, as for the state of charge no lower than 3 volts a cell. Quote Link to comment Share on other sites More sharing options...
David Martin 2 Posted January 22, 2008 Author Share Posted January 22, 2008 Thanks for the advice chaps, all taken on board.Still not dipped into the tin but these look just the ticket....http://www.giantcod.co.uk/lipo-battery-cell-lipo-battery-c-1_113.html?osCsid=7a96cc0fc2e2da0f3145ae22988b97bcMaybe the 1000mah one as a tester.....or the 800.....Brian, I was thinking of turning the pack sideways as well, may fit in the Hughes body.. Quote Link to comment Share on other sites More sharing options...
Brian Daniels Posted January 22, 2008 Share Posted January 22, 2008 i would think it would, mine doesnt stick out, infact yheu do look like they will do the job very well...the only other downside to going lipo is the need for a lipo charger...now there is a whole new topic!! Quote Link to comment Share on other sites More sharing options...
Owen Hailey Posted January 22, 2008 Share Posted January 22, 2008 Hi allhave seen lipo chargers on Ebay in Chiner shop For as little as £3 pound plus postage. Quote Link to comment Share on other sites More sharing options...
David Martin 2 Posted January 23, 2008 Author Share Posted January 23, 2008 These chargers are being used by a mate of mine and has had no trouble at all...http://www.rcmdirect.co.uk/store/index.php?main_page=index&cPath=101_78They are similar to the one that comes with the Twister CP heli, except these do 2 or 3 cell lipos at a constant rate of about 800mah from a 12v source. Auto cut off and balancer incorporated as well for £10.99 if ordered on their own or £7 if ordered with an RCMDIRECT lipo.I charged the supplied Twister 3s lipos on mine about 60 times each until they faded a bit. Probably due to me stretching one or two flights a little longer than I should have, but I've had no issues with them at all.My mate charges 1800 and 2100mah packs on one and just has to wait a bit longer. Quote Link to comment Share on other sites More sharing options...
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