I know that. I would just like to keep this paramotor on somewhat of a budget. I am getting fairly high end components but I don’t have the money to go and get the best of everything at this point. So for me the batteries are a bit of a compromise. The 30Q are still pretty good but there are still better out there.
I’m thinking it’s time to go 21700 cells for these and stop playing with 18650 (SP 140 would benefit from this as well)
MOLICEL/NPE INR-21700-P42A 45A 4200MAH FLAT TOP 21700 BATTERY
22Sx11S is 46.2ah at max 495AMP capability at $1452 dollars + shipping.
the molicell can deliver a short period of time of up to 25 A. peaks at start up to 30 A. permanently 20 A. then the temperature in the delta remains below 30 degrees cesius. at start the battery means 20 degrees celsius after discharge with 20 amps 50 degrees celsius. that doesn’t matter to the battery, it will last a long time. but of course you need less than 10 amps for normal flying. with show flights oder high altidude powerflights you have enough reserve. example is for a 15 series, 10 parallel pack. the available power is a good 3750 mah. this is a very good value when discharged to 3 volts under load. a perfekt Setup in the max. 60 Volt class of e-ppg is: 15 oder 14 S with 16 paralell. power enough for all kind off flying. incl. Pylon race.
Or you could build an 22s16p 30Q battery pack. It would weigh 2 lb less, have an extra 1ah (48ah)(actually the 30Q is a 3150mah cell so it would be more like 3.5 ah), and it could handle 240A constant and 320A peak which is close to what the Molicel is under realistic use. All the 30Q cells would cost $1232+ shipping.
I do know that under load the cells will heat up and it will lower the specs, but it just shows that the 21700 isn’t that much better than the 18650 cells. Tesla still uses the 18650 cells in their more expensive cars for a reason…
As soon as someone gets the sp140 they should disassemble the battery pack. I’m dying to know how it was built and what cells it uses. I must point out that paracell using 14s24p hg2 cells can get like a 70 minute max flight time and more realistically a 60 minute flight. With the 336 Cells they are using it would put just the weight of the cells at roughly 34 lb which is pretty close to the roughly 30lb that sp140 has…
Also between the 18650 and the 21700. I heard somewhere that Tesla had a hard time build cars at first with the 21700 cells because they had higher core temperatures which was decreasing the life span. Does anyone know anything about this?
I want a paramotor with a bigger battery and longer endurance so I can go explore these mountains and go camping in them. My house is about 5 minutes from these mountains so I wouldn’t need to drive an hour to a flying field. So if I have an hour of free time and the weather is right I can just throw the paramotor in my vehicle and be flying in 10 minutes.
the samsung zell 30 Q version 2. (the newest) delivers a maximum of 2900 mah at 15 A discharge at 3 volts under load discharge voltage.
additional info: the molicl 21700 weighs exactly 66 grams. 70 grams is often incorrectly stated.
I was basing the cell weight at 67g which seems quite common.
How does the 21700 compare to the 18650 with voltage drop?
If that is your goal then you should DEFINITELY get some free-flight paraglider training, even if you only intend to fly there on your motor. Flying in the mountains in Utah is no joke. I’ve been in 1000+ FPM lift at 7:00 PM before, and I’ve heard stories about pilots being completely unable to get down by sunset flying at point of the mountain. I’ve also experienced the rowdiest turbulence I’ve ever felt flying in Utah. You can put yourself in a really bad situation really fast if you don’t understand what is going on around you and how the conditions are changing.
Nothing will help you understand mountain flying weather dynamics like free flying. I have six different commercial pilot ratings including sailplanes, flying professionally for the last 16 years, and I never really understood what was going on with air in the mountains until I started paragliding.
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Since we have many mountains in Austria, the Alps are always mandatory for us before we can fly with a motor to do all the licenses in a flight school. A = license = you can fly in the glide angle range of the mountain. B = license = you can fly more distances / XC. but you have to show that you can fly thermally and the most important fast descent maneuvers. Motor license. here too you have to take an exam. I think the good basic training means that there are very few accidents. it is also normal here for some pilots to fly with their motor at lunchtime in hard thermals. as mr jakodowski says. if you want to fly close to mountains or fly in thermals, good training is essential. if you only fly in the evening and good weather, you won’t need any rapid descent maneuvers. but you are much safer in the air if you still master it because you are less surprised and react more correctly. gusts and lee rotors can occur due to wind shear even in nice weather.
Where @Bob27 lives in Utah understanding rapid descents is crucial, particularly for evening flying. The desert glassoffs there (I think they call it restitution outside the US) can be extremely strong until even after sunset. It’s not unusual for new pilots to get trapped in the air until after dark at the north side of the point. The last time I flew there I was climbing 500-600 FPM any time I got below 2000’ AGL, almost no matter where I went. I spent a looooong time spiraling down out front and it took me a couple of tries to set up my landing approach low enough that I actually made it down to the ground. It’s fun, easy flying until it isn’t. There is nothing worse than being in the air wishing you were on the ground.
Exactly. When the sun hits these mountains just right it will create some very strong lifts and when the sun is only shining in the valley the air sinks very fast. As a noob I won’t go directly to flying in the mountains, I will likely go closer to the lake where the air is more calm.
I have seen crazy videos of people flying in these mountains and the lift that you can get but not all the videos end happily. One must be very careful of when and how they fly these mountains.
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If you want to kill your lift and decent quickly you could always gently pull down on your centre A-lines…
(Sorry about the terrible picture, it’s from a VHS tape I made in Turkey back in 2002)
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On this paramotor I will shortly be building I would like to make my own battery pack. One thing I want to try with this battery pack is fully encasing it in a sealed aluminum box like what the SP140 has. On the outside of the aluminum box I would have cooling fins CNC machined into the box or Tig welded on. My big question is, how would you efficiently transfer the heat from the batteries to the aluminum? I have played with many ideas but i still can’t think of a good way that wouldn’t add 5lb of weight or make the chance of short circuting the battery higher.
There are a few reasons why I would want to do this. First I want to do this because often times paramotors will get wet under various circumstances that would have been hard to prevent. The aluminum box would protect the BMS from water damage and the cells from short circuiting and corrosion. The other reason is that a few paramotor batteries have burst into flames during flight. This may be a rare occasion but if the batteries where in a solid aluminum box which contained the fire, it could save a life and a few thousand worth of equipment.
I’ve been trying to come up with a cost effective solution to building a quality pack. cost and quality don’t work well together.
Research I’ve read shows that the tops and bottoms of the cells get hot first then sides.
I was looking at a metal that would take the heat away from the sides. but that seems like it’s hard make the shape and precise.
Next option I was looking at is using those blue thermal pads but its super expensive.
so the hunt still continues.
Interesting, you can get like 100 of the 1.5x1.5cm blue pads for about $5. If you could put one of the squares over the zink strips at the end of each battery and have those connect to your heat sink it may work. It would only cost about $30.
I am concerned that it may not cool the center of the cells very well and the internal air temperature may get quite hot.
if you have a flexible metal like copper sheet and sandwich 18650/thermal pad/copper and tie that to the end/outside of the metal case, could work? that was my initial idea.
It would suddenly get very heavy but I think it would likely work. I was trying to think if how to efficient weave a large guage of copper wire through the batteries to do something like what you where thinking, but I don’t believe it would be efficient enough to keep everything cool.
for some e-ppg, i have packed the batteries in foam. that means even isolated. I create my concept so that I don’t go beyond the limits of resilience. this increases the lifespan very much and has an overall high degree of efficiency. a good eppg needs a maximum of 200 A at full throttle and 70 -80 A in cruise mode. at 300 A you can fly a trike with a takeoff weight of 400 lbs.
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You should just build the pack and the case and do some testing to see if it requires cooling at all. There is some new research about lipos (not sure if it also applies to Li-ion) that suggests they last longer if they are slightly warm while discharging. Some guys are even pre-heating their batteries. Anything metal that touches the cells other than the connecting strips is risking a short. Adding a bunch of metal inside the pack to increase passive cooling might actually be increasing your overall risk of pack failure instead of decreasing it. It’s quite possible that you’re trying to solve a problem that you don’t actually have. Like @bratwurst said, a lot of people have encased their cells/packs in foam, epoxy, ect, and end up with the cells being MORE thermally insulated vs. a normal pack, and these guys seem to be doing fine.