7.4V batteries. 10 mins flight time? Is that normal?

Nazty

Active Member
I finally got my first build to work. I took it out for a spin. And collectively I think I only received 10mins of flying time. Well sort of flying. I've never flown a drone before. It was kind of hard to get it going. But when I started the quadcopter again after many failed attempts I couldn't get it running. Turns out the battery won't run the quadcopter when it hits about 5V. I'm guessing that has to do with the Naze32 board which runs on 5V? I'm new to this so I'm not totally sure what the exact problem is. But, is it normal for a drone on 7.4V battery to run for only 10mins or so?
 
There's no way we can tell you if this is an expected flight time without a description of your quad. Size and type of frame, motors, props and any accessories like camera, vtx, etc. But if I'm interpreting your post correctly and you're saying you've let your 2 cell battery drop down to 5 volts, then you've probably already severely damaged it.
 
But why? lol. I did ruin a Rx from putting the ground and signal wires in the wrong section of the battery. Did I ruin both the battery and Rx? Also, why at 5V is when I run into issues?
 
Maximum cell voltage 4.20v
Minimum cell voltage 3.70v
Although I will let it drop to 3.5 on some battery's. Storage voltage is 3.80v don't ever let them go below 3.5.

See 3.7+3.7=7.4v low charged battery. a full charged battery is
4.2+4.2=8.4v so really it's 3.8 you should not go below.
 
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mozquito dude

and other dudes dude

you guys are dripping with practical experience


if you guys could take a moment to cook that down into a concise, inclusive read about batteries it would be way cool for all of us new suckers - there is a lot of information to learn about LIPOs i guess, but it takes *months* of pecking around the net to absorb it

eg. once a newbie figures out that "3s" is the same as "3 cell" it is a step forward. no one is born into this world knowing "s" is an abbreviation for "cell", and because of it, you get weeks of reading information that one is unable to absorb. a newbie doesn't know whether "s" is "cell" or some other parameter that they don't know about yet.

but it's pretty clever, how "s" is "cell" because they sound the same. "oh well that settles it for certain"

what are the practical performance pragma of a 2s versus a 3s versus 1 or 4 or 429? where are newbies supposed to find out, except throwing money away until they finally get enough experience to know?

if you are using a 3.7v, then *i guess* you can use a (imaginary) 4.7v as well, as long as it has sufficient amperage???? you can use higher voltage. as far as i'm aware, you need a minimum amperage for electronic circuits to operate, and they would also have a maximum the components can physically handle.

you know, i'm almost 50 and write my own software and all of that stuff. but i have never owned a "personal electronic device" like a cell phone because i don't want people calling me all the time. so i don't have any experience using batteries apart from aa aaa c and d that were around a half century ago. to find all thsi stuff out, i gotta read the wikipedia on LIPO technology and screw around for hours until i can wheedle all that crap into practical information pertinent to this material.

why can't someone just write it somewhere and make it a sticky EH

moz you say
max 4.20
min 3.80

but for what???? all batteries in the world? batteries named claude that like to dress up as fusiliers and go on holidays n the seychelles? what are we talking about here mate? can you qualify that data for readers pretty please :) i mean, the dude is talkign about 7.4 v and it dies when he hits 5v, so i can't see anyhow how 4.2 relates to what was discussed previously :)

are you saying that minimum usable power of a battery is about 90% of its rated voltage? i can't tell, confused by too much imagination here for reals.


OP - as far as i can tell from watching other people fly quads, and from the short amount of time with an eachine e011 before it flew away, yep, as people say, the "minimum" operating voltage is pretty high in comparison to the rated value, which makes sense really. you're not going to fly at 0.2v left ("reductio ad absurdum" = logic is the single most useful thing you can learn to improve the quality of your discourse and rhetoric and rationale). the e011 (and a lot of other quads it seems) is rated at about 5 minutes. some commercial models are lower than that for racing. i saw a guy on youtube with a balsa frame and arduino who had a 30 minute flight time, definately not a racer build tho.

it's kind of a weird paradigm - today you can buy all these parts and plug them into each other and build just about anything, without having to know anything about electricity. in my experience, electricity is taught like a lot of other technical fields, there is a lot of intentionally confusing information in the entry level information to keep the riffraff out..... eg. the way people insist that programming c is not easy, or that math is hard, especially if you are a girl. anyway congratulations on getting into the air! :)
 
You are using a 2series lipo so each cell has a max 4.20volts charge capacity.
& a minimum is 3.70volts. Same with 3&4 Cell. If you have run a 2cell 7.4v battery down to 5v then divide it by two.
So you let it run down to 5 when it says on the battery 7.4v. That is the lowest it should be run down to. You ran it down to half what it should be. They can be fixed. But it's dangerous but I'm not telling you at this stage. And no S does not mean cell it means series as in 3cell in series. Ok
 
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cook that down into a concise
Cliff notes version................
Lipo batteries are advertised as "nominal" voltage of 3.7v per cell. Generally this is considered the minimum you should allow your battery to run down to. If you run a lipo cell below this, you are flirting with catastrophic failure...............intense fire up to and including exploding.

The same holds true for over charging. Max charge should be 4.2v per cell.

As noted the "S" in a 2, 3, 4 or more, denotes series. Nominal voltage per cell= 3.7v, 2s is 2 series cells.......2 x 3.7 is 7.4. The same applies to a full charged Lipo Battery...............2s is 2 x 4.2(4.2v max charge per cell) or 8.4v.

An "old school" analogy..................12v car battery. If you hook positive to positive(negative to negative)you have created a "parallel" battery. You've combined the total power available of the two batteries, but the voltage remains the same.....12 volts. If you hook them positive to negative, you've created and "series" battery................voltage is equal to the sum of the voltage of both batteries....in this case 24 volts. But the overall power is an average of the power rating of both batteries.

Other multi-cell battery assemblies(nicad, li-ion, etc) do not have as efficient weight to power/voltage ratios. So almost all the talk of batteries involved with RC devices are almost all Lipo.
 
Yay you are a bit lippy for my liking. Can you see where the 4.20v comes into this now its been explained. I only come on this site to pass time while I'm in work. If funny bugggers like you are going to comment on my short apparently unhelpful answers. I'll just watch some pornhub instead or skip your posts in future.
 
Thanks for the response guys. The explanations were enlightening. Better than Battery says "ouch"! I don't know why I was every expecting a 1 hour + long battery life. I'll look into the math of how to expand the life time of the battery. Or at least how to get a longer flight.
@yay, you ever been on StackExchange? Hah, pretty similar occurrences on there
 
I don't understand electronics either, some things in this hobby don't seem to made sense. For instance: my heavy as hell syma x8 flies for 12 minutes, but my tiny qx90 only flies for 5 minutes. Although now that I think about it the syma is a slow cumbersome flying block and the qx90 zips around like a sparrow on steroids. I'm guessing it's a formula similar to (weight x motor power x energy output).

10 minutes flight time is pretty good.
 
hell syma x8 flies for 12 minutes, but my tiny qx90 only flies for 5 minutes.
Let's see............QX90, 1s, 600mah, 3.7 to 4.2 volts. "mah" is the amount of power in your tank. X8, 2s, 2000mah, 7.4 to 8.4 volts...........bigger tankful.
 
Let's see............QX90, 1s, 600mah, 3.7 to 4.2 volts. "mah" is the amount of power in your tank. X8, 2s, 2000mah, 7.4 to 8.4 volts...........bigger tankful.
Yes I understand that but the qx90 weighs only 39grams and the syma is a hefty 450 grams. I'm guessing the weight to power ratio of the different motors is why there's a big difference in flight times. I.E.-the smaller motors are actually more powerful in the qx90 than the bigger motors in the syma when compared to size of the actual quads. The more powerful motors use more juice.
 
the smaller motors are actually more powerful in the qx90 than the bigger motors in the syma when compared to size of the actual quads.
No, Dog............different applications, different power transmissions. That like comparing my 85hp John Deere tractor motor to my 82hp Honda motorecycle motor. Also the tank size. My tractor holds about 30gals, my bike holds just under 5gals.

My bike will run 130mph on a good day with just me on it. With my wife........90 is tops. Can't pull poop, won't really handle any load and a tank lasts about 3 hours(my driving style.......).

My John Deere 4020............will run all day on one tank. Top speed is about 22mph, but I don't run it by speed but by engine RPM. 2000RPM. But that sucker will pull the world if I got an anchor point. I once pulled a full concrete truck that the front axle was buried.
 
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! used to have a 220cc yamaha dual cycle and it didn't go much past 80mph. people trying to kill me on the highway for kicks. short trip.

hey my post from yesterday is still in the reply box! >>>

i'm gonna take it upon myself to note all this stuff and make a page ... each new person has their own experience and various disciplines that translate, a cheat sheet on all kindsa stuff would be an awesome read. because more and more people are going to start using quads.

example of application:

the length of an antenna corresponds with the wavelength of the signal. antennae for 2.4gHz should be 31.25mm long (iirc from last week) and that ought to be linear.

a small bit of technical information with practical application: i opened my second eachine e011 today and found the antenna was sorta curled around. the last one wasn't. it will still work but at reduced range, and straightening the antenna will help get the most range (i'm new at this but the folks i picked that up from aren't). beign pretty stupid, i was previously thinking that extending the antenna would increase reception. nope.. resonance to wavelength = good.

simply, a cheat sheet with a bunch of brief informations like this all pertinent to getting your new quad in the air regardless of your tech b/g would be the dopest, illest, whatever the kids saying nowadays deal.
 
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