Robert Cooter Posted April 8, 2008 Share Posted April 8, 2008 Hello, I need advice on charging lipo 2500mah 11.1v battery for my trannie as the lead to the trannie is light weight I,m at a loss to charge rate .Do i charge at 1c (2.5a) or at 250 mah trickle anyone advise me please? Bob Cooter. Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 8, 2008 Share Posted April 8, 2008 Robert, firstly you should disconnect the pack and remove it from the tr before charging. Some have a PCM unit built in to them, and these do not like a "fast charge" ...I always do mine at .5C. Mine are, I suspect, the same as yours @ 2500m/a and DO have a PCM guard. Incidentally, what voltage are you letting them drop to before re-charging? Quote Link to comment Share on other sites More sharing options...
Robert Cooter Posted April 9, 2008 Author Share Posted April 9, 2008 Thanks Timbo,it is a 2500mah and has a pcm guard I purchased it from Hobby world which says one is fitted! So i will charge at 1.25amp on li po charger. With regard to voltage drop I was relying on the trannies meter to get to 9amp or so that would be 3volt per cell assumming the pack is properly balanced ,checked cells I read voltage on the cells3.95 2nd cell3.91 3rd cell3.94 wich i assume is fully charged. Regards , Bob. Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 9, 2008 Share Posted April 9, 2008 NO! Do not let them get to that point - 3v per cell is fine when using at a fairly high discharge rate, but at the low currents in the tr you are asking for trouble. Consider the following... At 9.0V your pack is completely empty At 11.0V it has less than 10% charge left.If it gets to PCM cutoff point - the transmitter simply shuts down - no warning! ( ask me how I know)Most transmitter alarms and voltage displays are way off accurateMany tr alarms are just too damn quiet to hear when actually flying!I adjusted my DX7 to sound off at the highest possible point which is around 10V - STILL TOO LOW!!So I have now built and fitted a seperate alarm with twin piezo alarms - this sounds off at 11.4V and gives me sufficient time to ensure a safe landing. Normally it would be best to recharge your tr pack when it reaches say...11.5V.Here is the thread outlining the mods.safe lipo use in tr etc Quote Link to comment Share on other sites More sharing options...
Robert Cooter Posted April 9, 2008 Author Share Posted April 9, 2008 Thanks for the info, its still worth changing battery system though isnt it? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 9, 2008 Share Posted April 9, 2008 Well I think so Quote Link to comment Share on other sites More sharing options...
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