To answer your question, the batteries were warm after the flight but not hot.
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One more thing regarding my 15 minute flight. I did one touch and go, went to 350 ft. and stayed there monitoring my battery life. I tried to manage power as frugally as possible to see how long I could stay aloft. When I added power the battery % might drop from 20% to 11% quickly, but it would return to a higher number ( maybe something like 17%) when I would back off the power.
Beautiful!
Cheers, Patrick
Here is how i have attached 2 x 4 battery boxes so you can just use one box for four bonkas or fill the other box with another 4 or just another 2 if you want to fly with 6
Dave
Looks like the average flight time with 4 x 22000 mAh Batteries is 24 minutes…
Current[A] = Capacity[Ah] / time[hrs]
So 44000 mAH = 44 Ah
24 minutes converted to hrs : (24/60)[min] / 60[min/hr] = 0.4
Current = 44Ah/0.4hrs = 110 A
Average Amps in a flight is 110 A
Run_time(min) = Capacity(Ah) / Current(A) x 60min/hr
Capacity: 44 Ah
Current: 110A
Run_time = 44/110 x 60 = 24 min.
Theoretical run time with my 4 x 22000 mAh (9.96 kg) + 4 x 16000 mAh (7.72 kg) = 76 Ah
Current 110A
Run_time= 76/110 x 60 = 41 minutes
Run_time with 8 x 22000 mAh Batteries = 88/110x60 = 48 minutes
Hope this helps…
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With a dozen flights on mine and with four bonka batteries I averaged 15 minutes. I just upgraded to 6 batteries and got 25 minutes (woohoo!). I have a power meter now and am tracking my power consumption. I’m assuming because I’m a bigger guy I’m getting shorter flight times than everyone else. Anyone else with similar flight times to mine? Maybe I need a faster/smaller wing???
Specs:
-Total weight (w/6 bonka batteries): 322.25 lbs
-Wing: Mojo4 XL
-Launch Altitude: 1391 ft
-Max Altitude: 2218 ft
-Total Altitude Gained: 2584 ft
-Watt Hours Consumed: 2769
-Amp Hours Replenished (from charger): 63.9
-Flight Time: 25.2 min
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I’ve been testing how long I can maintain maximum throttle.
From fully charged down to 42 volts (at max throttle), with six batteries, I am currently getting 11.5 minutes. Using six batteries they don’t get hot.
In that time I was able to gain 1916 feet for a climb rate of 2.84 ft/sec.
Anyone else tracking their numbers?
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What is your body weight? Judging by the mojoxl we may be close.
I’m 220 lbs, total weight with 6 batteries, harness, motor, wing, etc is 322 lbs.
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I’m also about your weight, I don’t have a unit yet, but if we can not change the weight see if you can try it on a bigger wing. The naxt batch is going to have more power and flight time.
The next batch should have higher volts and lower amps. The Watts should be the same so don’t be expecting more power. And bigger batteries give longer runtime but we can already do that… the more battery weight you carry the longer you fly so nothing has changed there.
What will change is the amps will be a little lower through the wires, connectors, ESCs, and the motors and therefore more robust.
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My Mojo 4 XL is a big, slow, beginner wing. I think it has a lot of drag which impacts my flight times. I am searching for a little better wing to see if my flight times improve.
I don’t typically use full throttle because it puts me over 90 amps per ESC and they are only rated for 80. Plus, I think the climbing efficiency is better with less throttle… basically that last little extra boost of thrust costs a lot in terms of power consumption with little gain.
Today I wanted to see how high I could go with 6 batteries but I wasn’t comfortable flying up through a wind sheer layer. So, I made three climbs (without landing) while holding the amps between 60 and 70. On the final climb I held those amps until the voltage hit 42 and then eased off the throttle to maintain 42 volts until my amps were down around 20. Note: I get level flight at around 40 amps so that last little bit only extended my descent.
My First climb was 6.5 min with 1050 ft gain, second climb was 6.5 min with 1200 ft gain, and the third climb was 3 min with 500 ft gain.
That adds up to 16 minutes of climb with an altitude gain of 2750. Maybe I will try to do just that next time I have more comfortable air conditions.
I weigh 180 pounds and with 6 batteries and everything including the wing I’m at 265 lbs
I fly a medium Skywalk Tequila 4. It’s mountain flying wing with an EN-B rating. The upper certified weight for this wing is only 242 lbs so I’m quite heavy on it with the motor. That’s part of the reason why I feel uncomfortable in the wind sheer because this wing gets quite active flying loaded in turbulence.
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Nearly the exact same climb rate with less throttle. I’ll try that and report back!
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Even if you don’t get the same rate you might get more altitude before the batteries die. It will be interesting to see the results. Not only do you have more weight and a big slow wing but aren’t you using different props too? Do you have an amp meter?
I’m using the wood props again, the carbon fiber wouldn’t stay on. Yes have a power meter to see the amps. I might not be able to test for a week or so.
My son weighs 30 pounds less than I do and he flew my motor and wing this morning. He held the throttle at 65 amps for 15 minutes and gained 3400 ft. When I do the same thing I only gain 2800 ft. Hopefully I can gain that extra 600 ft with a new and larger wing. I’m 30 pounds over the certified weight of my wing when I use 6 batteries.
3 Likes
I’ve been collecting data for climb rate with different amp draws. I find it interesting how linear the data is even when I include zero amps, which is my descent rate (-278 ft/min), and 36 amps which is level flight:
I combined the equation above with battery capacity to chart how high I can climb with 6 batteries as well as how long I can fly. I didn’t test above 75 amps but I extrapolated to create the last 3 rows (I don’t ever go above 80 amps for an extended period). The flight time calculation includes the descent and matches pretty close to what I see in calm conditions with batteries that are well used and starting to puff. I should be getting new batteries next week and I hope to see longer flight times with them:
Here is a graph of the maximum altitude:
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Approximately what thrust does that correspond to to maintain level flight @36A per motor?