Tim Mackey Posted February 17, 2008 Author Share Posted February 17, 2008 Thanks Bruce. I agree it could be seen a s thyristor, but not a resistor as such - just think of it as very fast on/off switch. Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted February 17, 2008 Share Posted February 17, 2008 A lot clearer now .Thanks to you both .Will probably have more questions as I go along.Again! Quote Link to comment Share on other sites More sharing options...
Piper Cub Posted February 21, 2008 Share Posted February 21, 2008 Er, what does WOT stand for and what is it? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 21, 2008 Author Share Posted February 21, 2008 Wide Open Throttle. What does it mean...well it means errr... wide open throttle ! Quote Link to comment Share on other sites More sharing options...
Piper Cub Posted February 24, 2008 Share Posted February 24, 2008 I was expecting sommat else! Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 25, 2008 Author Share Posted February 25, 2008 STDY-PC Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted February 25, 2008 Share Posted February 25, 2008 ? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 25, 2008 Author Share Posted February 25, 2008 Sorry To Dissapoint You - Piper Cub Quote Link to comment Share on other sites More sharing options...
Tom Mann Posted February 28, 2008 Share Posted February 28, 2008 Aha.This might (pls confirm) explain my bafflement whilst 'improving' on my electric swift chopper. Whilst footling about spooling up and down alot and trying not to break the ruddy thing I seemed to get reduced flight time out of my lipo. but yesterday i hovered well non-stop and bejeesis the thing just kepton going. my concentration went before the pack did.~What I'm thinking is that all this heat mentioned above is energy after all, and so is 'wasted juice' and that's where my missing flight time went?tom Quote Link to comment Share on other sites More sharing options...
Fats Flyer Posted March 5, 2008 Share Posted March 5, 2008 Hi Timbo,When using brushless motors on multi's, why do they recomend a seperate lipo pack for each motor?thanksvince Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted March 5, 2008 Author Share Posted March 5, 2008 Well I'm not sure that this is always a necessity personally. The important thing with twins is to use 2 x ESCs whether from one battery or two. The problem is of course that even matched ESCs could activate the LVC circuit at different times, and this could mean one motor shutting down before the other, with consequential motor torque / yaw effect. I personally never fly to LVC, but in a non planned for situation it would be nice to know that both motors shut off together. This is a subject under discussion from about page two of this thread here Of course...certain model layouts may well dictate 2 batteries being necessary, such as keeping motor and battery leads short and so on and the total power requirements of both motors might also make 1 x battery impractical. Quote Link to comment Share on other sites More sharing options...
Fats Flyer Posted March 8, 2008 Share Posted March 8, 2008 cheers timbo Quote Link to comment Share on other sites More sharing options...
iawnski Posted April 12, 2008 Share Posted April 12, 2008 blumming eck me heads gone to peices with all this wake me up in the morning /hope im just an old fashioned glider pilot when i awake cheers timbo Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 12, 2008 Author Share Posted April 12, 2008 What you need is a good session in a nice strong westerley...- I am just off right now to the big rock ! 15mph s/westerly, sunshine and showers. Quote Link to comment Share on other sites More sharing options...
iawnski Posted April 12, 2008 Share Posted April 12, 2008 im there with er indoors this afty darent even look at it gota shop shop shop (yawn) wont be long ill b there / enjoy it timbo jammy begger cu soon iawnski kev Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 12, 2008 Author Share Posted April 12, 2008 Just returned after a very nice couple of hours - super weather up there today....didnt want to come back home but the grass needs its first cut etc etc...boring Quote Link to comment Share on other sites More sharing options...
Piper Cub Posted April 27, 2008 Share Posted April 27, 2008 Im in the process of charging & balancing my Lipo pack. Its a 3200mAh, 4S, 15 - 25C pack.I've set the charger up at 1C = 3200mAh, pack voltage 14.8. There is no facility to set individual cell voltage as the charger detects this automatically. The charger is a Mega Power Poseidon 860DS The charger is showing a voltage reading of 16.875V during the charge and balancing cycle (instructions advise the charge leads and balancing lead are connected at the same time). Is 16.875v ok for a 14.8v pack? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 27, 2008 Author Share Posted April 27, 2008 4s nominal voltage is 4 X 3.7 = 13.6. When full the pack should be 4 X 4.2V = 16.8V Quote Link to comment Share on other sites More sharing options...
Leonard Broese van Groenou Posted May 2, 2008 Share Posted May 2, 2008 HI I am new to electric flight and have just bought the Multiplex Multicharger LN 6015. It was recommended as it is able to charge/discharge all kind of batteries. My problem is that the program asks more questions than I can answer (yet). I have the following questions:For Lipo batteries the manual recommends charging at 1 C. How do I calculate the discharge current? Is it a function of the battery capacity? For NiXX batteries how do I set the charge current? In the manual it says that the "normal" charge current is 1/10 of the battery capacity so if the capacity is 700mAh the charging current should be 70mA (which would, I guess, be the slow charge rate). What would be an acceptable faster rate?Discharging NiXX batteries requires input of a discharge current and a final discharge voltage. I have not seen a recommended discharge current. As a final discharge voltage I have been advised to use the number of cells times 1V. Is this correct?I am using one 4.6V 700mAh Nicad and a 6V 1500 mAh NiMH battery. Your feedback is much appreciated as I am very much at sea at the moment. Leonard Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted May 2, 2008 Author Share Posted May 2, 2008 Hello Leonard and welcome to the forum.1) You should not use the charger to dischrge LiPo batteries - they do NOT benefit from cycling, just use them in the model you are flying and then simply re-charge / balance-charge2) Nixx cells should be charged at approx 1/10th C for a slow rate and the maximum ( high /fast rate ) depends on the battery specifications. Most of them should be happy up to around 2C but check what it says on the particular pack. Incidentally, when charging NiMh cells use around .5C at least to ensure that delta peak is detected correctly by the charger.3) Discharging Nixx cells is usually limited by the charger capability, most usually set it at around 2-3A maximum, there is NO BENEFIT in discharging them quickly, so personally I would leave it at around .25C As for the final voltage after dischrage, Nixx should be taken down to 1.0v per cell, so yes advice is correct Hope that helps. Quote Link to comment Share on other sites More sharing options...
260 Flyer Posted May 3, 2008 Share Posted May 3, 2008 TimboI'm planning a 180W power system that will have a max (peak) draw of 18A on a 3s1p pack. Should I go for a 1800mAh 20C pack,or for the same cost and a similar weight I can get a 2200mAh 15C (25C burst). Static runs give a max of 17A so I have some headroom on the C ratings.What to do? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted May 3, 2008 Author Share Posted May 3, 2008 2200 - this will still be only pushed at around 7 to 8C as the actual current when flying will reduce to about 14 / 15A The bigger capacity will give you longer duration - but will probably weigh a little more than the 1800. Quote Link to comment Share on other sites More sharing options...
260 Flyer Posted May 3, 2008 Share Posted May 3, 2008 Thanks Timbo!That was my gut feeling as well. It came about when I was looking around and saw a 30C pack and thought woo 30C! Then I thought hang on a minute what advantage would 30C give me? (unless I'm designing a EP rocket with a "burn" time of a minute ) Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted May 3, 2008 Author Share Posted May 3, 2008 Correct... Quote Link to comment Share on other sites More sharing options...
JohnnyB Posted June 30, 2008 Share Posted June 30, 2008 Hiya Guys,Well, where to start? Yesterday Mrs B and I had a really fantastic day out at Wings & Wheels at North Weald. Then with David's recent brief review of the Ultramat 16 in the July RCM &E still buzzing in my head, I went and bought one.So up early this morning to get to grips with the instructions. These seem reasonably straightforward for a complete novice such as myself. BUT, this question of charge/discharge rates is still confusing meThe battery I decided to practice on is from my Twister Medevac and is a 2 cell LiPo of 7.4V and a current of 800mAh......So, am I correct in thinking that the C rate will be .8A. But what about Discharge rate when cycling. Also, what is the minimum voltage you can discharge to?.To add to the confusion, I have connected this battery up with a setting of C .8 but all I get is the error message of "contact break" although all conections seem to be perfect........Will I ever get my head around this electrickery........??Hoping someone can help.John. Quote Link to comment Share on other sites More sharing options...
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