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Model Forum / Radio Controlled / Air Models / May 2004Starting up in Electric Flight - What chargers ?
Hi, I am starting up in Electric Flight and wondering what are the best value chargers around. I need to have a charger that can deal with Lithium Cells probably Lithium Polymer, as well as Ni-Mh. I will need to cover a reasonable range of voltages that are commonly used. Other than Brushless Motors and Lithium Polymer Cells I will not be buying leading edge development stuff. Is it best to have have a slow charger for home use and a fast charger for field use or is the job done most economically with just one all round charger ? I've been out of the hobby for a while, just having a flight now and then on a friendly farmers field. So I am looking at three local clubs. However, its pointless waiting until I bump into the right person to ask at a club when there is a newsgroup! The only chargers I have at the moment are two Futaba Tx & Rx battery chargers, one old charger just for my old glow battery! and a couple of 12volt chargers for car batteries. So its all slow charge gear. I need to get up to speed on what speed controllers to use. I think a BEC is essential from what I know so far, but what other features should I really need?  SignatureCheers Blagard All Email, outgoing and incoming checked automatically with Nortons Antivirus >I am starting up in Electric Flight and wondering what are the best value >chargers around. Visa usually works well. Dr.1 Driver "There's a Hun in the sun!" Please submit your number, I would be delighted to check out how well it works and even duration! It would make a very pleasant change to my Mastercard. ;-) Cheers Blagard > >I am starting up in Electric Flight and wondering what are the best value > >chargers around. > > Visa usually works well. > Dr.1 Driver > "There's a Hun in the sun!" > Hi, > [quoted text clipped - 21 lines] > essential from what I know so far, but what other features should I really > need? Forget NiMh. Its the worst of all possible worlds. Go Lipo and get an Astro 109 from west london models. Its a 12v charger so the other thing to get for mains charging iais a 113.8v power supply. Usually one or two ex CB radio supplies on E-bay. > > Hi, > > [quoted text clipped - 27 lines] > Its a 12v charger so the other thing to get for mains charging iais a > 113.8v power supply. Usually one or two ex CB radio supplies on E-bay. I would have thought that 113.8v a bit of an overkill for a charger designed to work from a 12v battery :o) >>>Hi, >>> [quoted text clipped - 54 lines] > I would have thought that 113.8v a bit of an overkill for a charger designed > to work from a 12v battery :o) Just shows how good they make em these days - can survive even an accidental typo :-) Question? LiPoly has high capacity and low weight and these days the discharge currents are getting higher and higher. However the charge current is still limited to 1C so they will take an hour to charge at the field. Nicads can be recharged quicker - typically 20minutes. Lipolys require an ESC with a tightly defined cut off to prevent discharging the cells too deeply - unless you rely on your own judgement (risky). Lipolys have been known to catch fire if an inappropriate charger or wrongly set charger is used. Price wise Nicads or NiMh win. There are trade offs for each type so it depends what you value. Regards Peter > > Hi, > > [quoted text clipped - 27 lines] > Its a 12v charger so the other thing to get for mains charging iais a > 113.8v power supply. Usually one or two ex CB radio supplies on E-bay. > Question? > > LiPoly has high capacity and low weight and these days the discharge > currents are getting higher and higher. However the charge current is still > limited to 1C so they will take an hour to charge at the field. Why only one Celsius, surly you mean one ampere, 'A', or 'a' but this is a little naughty, try this site it should help the use of the correct notation: http://polk-burnett.apogee.net/pd/aploa.asp Vaughn 1C refers to the capacity not Celsius. So a current of 1C for a 1500mAh pack is 1500mA. Regards Peter > > Question? > > [quoted text clipped - 10 lines] > > Vaughn > Question? > > LiPoly has high capacity and low weight and these days the discharge > currents are getting higher and higher. However the charge current is still > limited to 1C so they will take an hour to charge at the field. But will fly for half an hour plus on the hour charge > Nicads can be recharged quicker - typically 20minutes. and fly for about 5 minutes. At vastly reduced performance due to added weight, than LIPOS. > Lipolys require an ESC with a tightly defined cut off to prevent discharging > the cells too deeply - unless you rely on your own judgement (risky). No, you sinmply don';t fly more than half an hour at a time without recharging. > Lipolys have been known to catch fire if an inappropriate charger or wrongly > set charger is used. True, so have Nicads. However LIPOS do burn better, So be careful. So does glo fuel. > Price wise Nicads or NiMh win. Not necessarily. Capacity for capacity its faorly close in small packs, Power for power Nimh wins and LIPO most expensie, but its not even +50%. > There are trade offs for each type so it depends what you value. NiMh take an hour to charge and typically offer you reduced power and duration and heaveir weight than LIPO,. Nicads are heavier, but can really produce teh power, bit to do that they flatten in a coule of minutes. For teh average sport flyer the best performance is LIPO. Ther is simply NO QUESTION about it. The ONLY caebvats are cost - s little higger in small planes, a fair bit higher in large, and the safety issues, whigh are dealt with by adopting safe practice. Nicads have a very slight edge for e.g. competition sailplanes where the huge discharge rates mean the better power to weight than LIPO is possible - for sub 2 minute runs times. NiMh is simply nowhere - long charge times, not great discharge capability, only average duration and not that cheap either. They also break and lose capacity when run hard. Believe me, if you are strating from scratch address the safety issues, buy a cheap motor but spend your money one decent LIPO pack and charger. You will get more bang for your buck that way. Some very interesting comments on the thread - and I will soon have to decide which way to go! TNO, you mentioned the Astro 109 charger. But what is a "decent LIPO pack" - Is there one manufacturer that stnds out from the others, and why? I am a little unsure about what packs I would use with a 400 size motor. I am starting off with a Micro Jet and that would usually take a 8.4V or 9.6V pack. LiPo packs straddle that voltage and I don't fancy the idea of burning out a motor by using 11.1V. Then again the 7.4V pack may not even give the same performance as a 8.4V NiMh pack. Or am I missing something! cheers Blagard > Peter Seddon wrote:------Snipped--------- > > Believe me, if you are strating from scratch address the safety issues, > buy a cheap motor but spend your money one decent LIPO pack and charger. > You will get more bang for your buck that way. > Some very interesting comments on the thread - and I will soon have to > decide which way to go! > > TNO, you mentioned the Astro 109 charger. > But what is a "decent LIPO pack" - Is there one manufacturer that stnds out > from the others, and why? There are two who stand out by dint of being the worst, one is Lucky something or other of happy pack or something, and to an extent there is kokam, the second worst. Together they comprise the sum total of what the UK distributors are handling. Yeah. No surprises there, then....Actually Kokam are not that bad - and the 340mA/h cell is THE cell to get for GWS IPS motors. There is one other manufacturer who stands out by dint of being the most aggressively marketed branded and packaged of them all Thunderpower aka ThunderBox. They are perfectly reasonable cells wrapped in hype and a 50% higher price tag then anyone else's. The best value for money cells are from enerland (www.enerland.com) variously sold in the states I believe as Apogee, Irate and Tanic, and now Polyquest. www.cheapbatterypacks.com is the cheapest place to get them. E-tech cells are similar to Thunderbox, in performance, but cheaper, and available from a couple of specialist UK outlets and one in the channel Islands, who by dint of VAT issues may be useable as a grey import channel. > I am a little unsure about what packs I would use with a 400 size motor. I > am starting off with a Micro Jet and that would usually take a 8.4V or 9.6V > pack. LiPo packs straddle that voltage and I don't fancy the idea of burning > out a motor by using 11.1V. Then again the 7.4V pack may not even give the > same performance as a 8.4V NiMh pack. Or am I missing something! The very best solution is to replace the stock motor with a 7.2v one which then delivers the same sort of power out of a 3s1p pack of e.g. e-tech 1200's, drawing 8-9A WOT. If you stick to the stock motor you need to use 2s packs, but the current draw is probably over 10A, which makes it a bit marginal on e.g. a single pair of 1200-1500mA/h cells. You can use 2s2p tho, and get extended duration, and a slightly larger prop will compensate for the slightly lower voltage. But of course the lighter weight of the LIPOS makes up or a lower power output. A 3s2p Irate 1100 pack, capable of 200W output and 22watt hour capacity, weights the same as an 8x600AE pack, capable of at best 100W output, and a mere 4.8watt hours. So for lightest weight and best power use 3s LIPO and 7.2v 400, for best duration use 2s2p and the stock 6v motor. The above rule falls apart completely when using a geared motor, because it turns out that the 6v motor on 3s1p revving at an infeasible 30K RPM becomes way the best option. BUT its useless to drive a prop direct at that RPM on most models. > cheers > Blagard [quoted text clipped - 4 lines] >>buy a cheap motor but spend your money one decent LIPO pack and charger. >>You will get more bang for your buck that way. Hi Blagard, Electric flight FAQ, lot's of info: http://www.ezonemag.com/pages/efaq.htm E-flight forum: http://www.rcgroups.com/forums/index.php?topic=air-elec http://electrifly.uk.com/ Met vriendelijke groet ;-) Ron van Sommeren near Nijmegen, the Netherlands -- Anti-Spam: my address must be modified. > Hi, > [quoted text clipped - 28 lines] > All Email, outgoing and incoming checked automatically with Nortons > Antivirus |
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