Hi all Gathering up some ideas on where to go for some upgrades in my flying. As mentioned in my introduction I fly some quads from WLToys, the V929 and V959. Those are not worth much in the windy weather we got here so I thought of getting something more heavy and powerful. I like the DJI F330/F450-type quads and their clones. I do much of my shopping at Banggood.com and have found that they have a clone named HJ450. Want to build it myself and my plan is to get that and some 930KV motors, 30A ESC´s and 1045 propellers because this looks as a well functioning setup. Planning on getting a KK2.0 controller for the brains. I have just ordered the Flysky FS-T6 Tx from there and it comes with a Rx so I will be covered on that. This Tx can also be used for my WLToys flyers. Or should i get a 330 size frame instead? I am still a noob on flying quads and don´t know which size is the best for me. Dont´t have plans for a GoPro, maybe a 808#16 at best, so the bigger size for this is no big deal. Any thought from anyone here?
I have experience with RC and jumped right into a SK450 and even on a day when I got really gutsy and tried flying in at least 20mph gusts it handled it no problem, the kk2.0 board is a great starting place for a beginner and I haven't had any problems with mine. I had some 1200kv emax CF2822 motors with 9x4.7 props and it flew great, just changed to 935kv emax multirotor motors and am going to run them with 1045 props but haven't had a chance to test it yet. If you do go the route of the kk 2.0 to at least flash to firmware 1.4 since that fixes the issues with the autolevel that the earlier versions had.
Not trying to talk you out of a bigger quad, but many mico's are good in the wind - the Hubsan Quads X4 and many others are actually fantastic in wind! Of course, you can't see them at a distance so they are no substitute for a larger model. But everyone should have one or two in the stable!
Nin3rsAllDay - The KK2.0 is allready in the house. Came flashed with the new V1.6. 930KV motors, props, 30A ESC´s and some plugs are on their way from China. Just need a frame to put them on. Don´t know yet if it will be the 330- og 450 size... Will need a battery, or two, or tree... too. Is 2200mA my way to go? Looks as if that is the size most users have. What brand and C-rate do i need? webman - Was thinking of getting the small V939 as I have heard lots of good about this little thing, and it uses the same Tx-protocol as my Fly Sky Tx
This is a good place to figure that out: http://www.ecalc.ch/xcoptercalc.htm?ecalc&lang=en You can play with different scenarios, and learn interesting truths like "A 4000mAH battery may only give you 30-50% more flying time that a 2000mAH one, because a lot of the extra energy is used to carry the extra battery weight". You need to talk with some people with a lot of electric flight experience to choose battery brands: I know that there are makers with a reputation for inflating their mAH and C ratings, but I don't have that experience, so I'm not sure who to trust. In general, the higher the actual (as opposed to claimed) C rating, the better, because it means the battery isn't working as close to its limits. But there's a cost trade-off you'll have to make, because it costs more to make batteries with highe performance. Also, be sure you read up on the importance of "conditioning" LiPo batteries before first flight: it can significantly increase their life. (Note: even though a lot of cheaper chargers, like the Accucel 6, say they can condition new batteries, they can't, unless the battery is really small. They don't have the discharge capacity to do it right. You may not find this out until you get it in-house, and RTFM) Spend the $5 and get one of those low-battery alarms that plugs into the balance connector: most flight controllers (especially the cheaper ones) only look at total pack voltage (if they even do that). It's easy when you're new, and just learning the limits to run a battery down to the point where one cell gets over-discharged. Especially if you're buying lower-cost battereies with cells that aren't perfectly matched. Ran
One of the best dis-chargers you can make is a few 1157 light bulbs (used in cars). They draw about 2.1 amps each, so you need to do math. If a battery is rated at 2100 Mah and has a 10C discharge rate (this numbers were chosen for easy math BTW) this means it can discharge at 21 amps safely. Math time, 21 amps divided by 2.1 amps is 10.......so 10 1157 light bulbs in parallel would draw 21 amps. Also, 1000 Mah equals 1 amp. Solder 10 1157 light bulbs together all in parallel, put your connector that matches the battery connector on the wires from that assembly. Get a DMM (digital multi meter) to monitor the battery voltage and / or add a low battery alarm (the type for the chemistry of the battery, lip, NiCd, NiMh) and connect this / these to the dis-charger. Plug in the fully charged battery and allow the battery to drop voltage to the amount that is safe for the battery chemistry. 3.1 volts per cell for LiPo, 0.9 volts per cell for NiCd and NiMh are the recommended low voltage points. Here is the best part about this type of bulb dis-charger, the lower the voltage the lower the current draw. As the voltage drops the bulbs get dimmer, when this happens the current draw of the bulb goes lower. This helps protect the batteries from over discharging. On NiCD and NiMH you can run them down until the bulbs are just a dim glow as those types of batteries can take that without shorting the cells. LiPos can not be discharged that low, so be ready to disconnect the dis-charger when they get to 3.1 volts per cell.....otherwise you can get a "puffed" battery or worse they could go up in flames. NEVER let a LiPo battery pack get below 3.0 Volts per cell. Advanced electronic dis-chargers have a relay that will automatically disconnect the batteries when they get that low. This could be added to the bulb dis-charger with a circuit like this http://www.gorum.ca/lvdisc.html. Generally, a new battery pack should be charged and discharged 5 times before being put into service. Charge the battery pack and let it cool down, then discharge and let it cool down......do not charge or discharge a warm battery pack, over heating a pack is bad. Every 10 - 20 normal runs with the battery pack do a charge / discharge cycle again....this helps the NiCd / NiMH battery packs from getting a memory and will let you know if the LiPo packs are getting weak and need replacing. More detailed information can be found here https://sites.google.com/site/tjinguytech/charging-how-tos
Everything else you wrote is great, but I have to strongly disagree with this part. A multimeter is somewhere between "very valuable" and "essential" for someone building their own electric aircraft, but it's NOT good for monitoring discharge: you absolutely need a battery alarm (preferably with an adjustable threshold). You may buy a pack with poorly-matched cells, or one cell might get non-obviously damaged in a crash. If all you're watching is the pack voltage, you can dangerously over-discharge a cell. Plus, it's unlikely that you'll sit there watching the multimeter (or non-alarmed cell checker) like a hawk every time you discharge. You need a monitor that doesn't get bored, or distracted by a phone call. If you're on a really tight budget, skip the cell checker, and put your finger over the beepers when you plug in the alarm: it mutes them enough to nearly eliminate the annoyance. If you're using bulbs for discharging, putting them in sockets allows you to adjust the load by adding/subtracting some. allelectronics.com (one of my favorite electronics surplus dealers) has 10 Ohm 25 Watt resistors for a buck apiece. The resistors have terminals that mate with the standard "quick-disconnect" connectors you can get from auto parts stores (or buy a bag from them: much cheaper). That makes it easy to adjust the load by connecting more or fewer in parallel. Even though they're rated for twice the power you'll be running through them, they still get pretty warm, so be careful around them when discharging. I mounted them on a piece of wood, and use a tabletop fan to keep a breeze flowing across them. That makes them "barely uncomfortable too touch", instead of "maybe raise a blister hot". Ran
Yep, you have to sit and watch, something you should be doing anyway with LiPo batteries as they have a tendency of flaming out when you least expect it. A DMM is the best way period, and should always be used to monitor battery voltage anyway. You are not relying on an unknown....the DMM is telling in real time what is happening. Even with my over-priced charging station and dis-charger I monitor what is going on with a DMM. I know for a fact the battery has charged or dis-charged correctly, and know when something is not right and can correct it before it becomes a problem. I also monitor battery pack temperature, over kill.....maybe......but if a battery heats up too quick for what it is supposed to be doing it might have a problem. LiPo technology is great, but it is also one of the most dangerous battery chemistry made today. Drop one, it might catch on fire. Discharge one too low it might catch fire. Charge it too long it might catch fire. Just using one normally it might catch fire.............they are light, make great power, and under most circumstances are perfectly fine....BUT, they might catch fire. Resisters work fine as a dis-charger, but if you read the part where I said that light bulbs, as the voltage goes low the current draw is less.....they act like resisters that varies resistance by voltage. At full voltage the filament is burning hot and has a low resistance, lower the voltage and the filament resistance gets higher. For NiMh and NiCd this is perfect as they wont let the cells short out, LiPos always need watching as they do not like to go to less than 80% of capacity and must be watched always anyway. I put plenty of warnings in my reply about LiPos, just because a beep is going to happen is not going to prevent a LiPo fire.....you have to be around to hear it. The best way to protect them is by being there, always, other than that the low battery cutoff circuit would be next best (but it too could fail). Bottom line, never charge or discharge a LiPo when you are not going to be there to make sure something bad wont happen......and yes, sockets are great for making adjustable dis-chargers......I prefer to make one for each type of pack I have whether it be 3S, 4S, 6S, 7 cell NiXX, 12 cell NiXX and on and on......and if a bulb blows it is still easy to change, just takes longer. I disagree with this though "I mounted them on a piece of wood, and use a tabletop fan to keep a breeze flowing across them. That makes them "barely uncomfortable too touch", instead of "maybe raise a blister hot". Wood??? really......wood burns....if you need some heat-sink material I have plenty, aluminum with fins and flat......http://www.wakefield-vette.com/products/natural-convection/thermal-extrusions-overview/CategoryID/15/Default.aspx
