Myron Beaumont Posted February 23, 2008 Share Posted February 23, 2008 Learn all the time ! Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted February 23, 2008 Share Posted February 23, 2008 Timbo Do you wait for " an hour or so " 'cos it takes that long to get through your daily supply of sticky buns or is there a serious reason & if so why? ( only trying to gain knowledge ) Quote Link to comment Share on other sites More sharing options...
Kelly Posted February 23, 2008 Author Share Posted February 23, 2008 Yes many thanksTimbo, like Myron says,learning all the time .Will do as you say. Oh and thanks for the compliment, have not been called 'young man' for some years now .Might start the P-40 tonight, four strokes seem less complicated.How is the Camel coming along?Thanking you,Kelvin. Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 23, 2008 Share Posted February 23, 2008 The camel is still in its box.....I am awaiting a different motor which should be here soon.Myron....the delay just allows the battery to stabilise and revert to room temperature- not strictly necessary, but in view of the specific testing we are doing in this case, I just wanted a "level playing field" as it were. Incidentally, remember that LiPo s will perform pretty poorly in cold weather ( all batteries tend to ) so try to conduct all your tests in the warmth if possible. At this time of year, I always bring any packs I intend to use imminently into the house and then transport them to the site wrapped and insulated. I then keep them in a warm woolen bag, in my coat pocket, and only fit them into the model immediately prior to launching. Quote Link to comment Share on other sites More sharing options...
Doug Ireland Posted February 24, 2008 Share Posted February 24, 2008 Hi guys, interesting stuff.The ESC I use is programmable (I assume they all are) to shut down at a specific voltage depending on the number of cells in the pack. Reading the instructions however, I noted that the default setting was for the ESC to stop at 70% of battery voltage. When powered-up the ESC would beep three times to indicate the number of cells connected to it the beep a further 7 times to indicate it was set to the 70% cut-off value. This is all well and good as long as the battery is fully charged the first time you switch it on. The ESC looks at the battery voltage every time it is switched on and then sets the cut-off point accordingly. If you had a pack was was only at say 10v then it would be below the 9v safe limit when the ESC shut down. Suffice it to say I had this setting changed so that now the ESC stops at 9v regardless of the starting voltage.I wonder if this is what happened to the chap at the start of this thread? Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted February 24, 2008 Share Posted February 24, 2008 Doug This is exactly what I as thinking on another thread yesterday as I had read it somewhere -You have explained more eloquently though .I just thought that the lipo should always be fully charged before connection to the ESC so that it would set itself to 70% automatically of the voltage at the time .My ESC is a Hifie & dont know if its any different from all the others or indeed is programmed to do whatever -whenever yet. My Prolux charger sets itself to my 4s automatically & tells me when every cell is fully charged with LED s & thats all I know at this time NEXT?? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 24, 2008 Share Posted February 24, 2008 Strictly speaking...the battery SHOULD only be connected to the ESC when it is fully charged in order for the ESC to correctly identify the number and type of cells. However, many ESCs these days will do as Doug's does, but it is advisable to check carefully the MO of your particular ESC. Personally I never worry about it, because I ALWAYS connect a fresh battery, then fly until it's time to land, remove the battery, and mark it ready for a recharge. I then use the next fresh battery.Incidentally, I NEVER fly to LVC anyway, and you will find the majority of experienced leccy guys do not either. It is bad practice, shortens overall LiPo life, and can be the difference between making that finals or not!After the maiden of every model, I check the flight duration obtained, then set my tr Timer ( ESSENTIAL if you are a leccy flier ) to 1 minute less than that figure. I then ALWAYS head for the strip immediately my timer sounds the 10 second countdown. I then find that on inspection, the battery has at least 10% capacity remaining or more.see here The learning curve continues guys....and never stops Quote Link to comment Share on other sites More sharing options...
Jon Posted February 24, 2008 Share Posted February 24, 2008 And I thought I was only going to learn to fly seems there just a little bit more to all this than just a few electrons moving from a to bThanks Timbo keep it coming ....whew! Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 24, 2008 Share Posted February 24, 2008 well actually they move from -ve to +ve not a to b electron flow..as opposed to "conventional flow notation" Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted February 24, 2008 Share Posted February 24, 2008 Guess what? my gear(futaba )doesn't have a timer facility Must dig out my clockwork alarm clock & clean the spring etc. Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 24, 2008 Share Posted February 24, 2008 get a little kitchen timer that you can stick onto your tr....perhaps er indoors has one that you can rob - oops I mean borrowPS is that the futaba 2.4Ghz you refer to ? Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted February 24, 2008 Share Posted February 24, 2008 Timbo Yep unfortunately Just voltage & low bleep alarm ! Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 24, 2008 Share Posted February 24, 2008 Another shortcoming then of the entry level Futaba offering of 2.4Ghz. How silly....especially as one of the big reasons for having 2.4G is for lecccy flyers ! Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted February 24, 2008 Share Posted February 24, 2008 Yes Kelvin it looks as though I was a little premature in suggesting you bin the battery......just goes to show you should always seek a second opinion!!! I'm still confused as to how a Lipo battery, having its voltage driven so low that it won't even move the servos, can survive though......My understanding was that if a Lipo dropped below about 2.5 volts per cell then it was dead, kaput, deceased, turned up its collector plates (I feel a touch of Monty Python coming on here..."The Dead Lipo Sketch"...it is an Ex-LiPo...it has ceased to be!!!! I will be very interersted to hear if it comes back to full performance after a bit of TLC.....Good advise on the flight times too....land once the sparkle goes out of the performance...driving yer battery down to the PCO point is just going to shorten the battery life & risk the aircraft as the PCO may cut in when you're low & slow & cause you to land out....not good!!!! Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 24, 2008 Share Posted February 24, 2008 I have ( only once ever ) let a small capacity LiPo drop to almost 2V per cell....and with careful trickle charging and a few dischrge cycles it came back from the dead as good as new. It is just the luck of the draw, sometimes you win and sometimes you lose Quote Link to comment Share on other sites More sharing options...
Kelly Posted February 25, 2008 Author Share Posted February 25, 2008 Well I did the discharge cycle and may do a few more just to be sure.I think if the esc was at fault I would have crashed on my last flight , This was first time I have flown until the motor cut off, the motor stopped downwind,came in to land straight away,controls still working normally ,I did have the correct esc setting for this flight (2 beeps).All this lecky stuff has worn me out .I am going to chill assembling the P-40 next week.My Wife (ground crew) has promised to learn how to use my 12 year old camcorder to video the first flight or crash of the Me109 . Thank you Timbo for all your help .Kelvin Quote Link to comment Share on other sites More sharing options...
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