SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Mar 22, 2015, 11:44 PM
Registered User
basnboy's Avatar
Australia, NSW, Vincentia
Joined May 2014
8 Posts
Help!
Battery Life, Battery Length .... where has all the power gone?

Hi. this is my first post, so feel like a kid first day at school - all wide eyed.

I have been mucking around learning the very uncoordinated art of building my first quad - thinking it would take a week not the 6 month in reality.

I have a s500 quadcopter (close to the f450) and with a stabilizer on it have it purring in a hold position for several? minutes. I am using a turnigy 2200mAh 3s battery. I have added on occasion a second (for fpv) a Twister cpx 3s 1200mAh . All loaded up I am carrying about 1000g (2lb?)

After adding a micro (entry level) fpv I now find the battery time is very small before it runs flat. I am only getting approx 3minutes fly time even on new batteries and they are charged slowly with cells balanced on an imax b6 charger.

Fully charged at 11.2-11.4v they stop the quad flying with 6 to 8v still showing.

What am I doing wrong that they are not discharging more fully and at approx 1000g (incl battery) why am I getting such short fly times? The set up is nothing extraordinary to call it power hungry. I do have an unused heavy battery - a tornadoRC 3S 40c but I suspect it be too much for the 30c ESC/motors and it comes in at a weight of 400g itself.

After such a build time I feel a bit premature with only 3minutes Is there a setting somewhere where the you can set the voltage to 'stop flying'? Is 1000g too much?

Your collective wisdom is much sort. thanks Rick
basnboy is offline Find More Posts by basnboy
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 23, 2015, 12:13 AM
Registered User
So. Cal.
Joined Oct 2004
8,738 Posts
What charger are you using? A 3-cell lipoly is 12.6 volts at full charge, not 11.2-11.4 volts. Further, if you've discharged them to 6 to 8 volts, they have likely sustained irreparable damage and should be replaced.
mrforsyth is online now Find More Posts by mrforsyth
RCG Plus Member
Reply With Quote
Old Mar 23, 2015, 06:14 AM
Jaketheone46
United States, KY, Florence
Joined Nov 2014
349 Posts
Yes you are on the wrong track voltage wise for sure. A Lipo cells nominal voltage is 3.7 volts per cell. 4.2 volts per cell fully charged. So this makes a 3 cell pack fully charged at 12.6 volts.
If you ran a 3 cell pack as low as you just stated you have done damage to the pack. And if the pack does still work it will not deliver the full capacity that it would have before running it this low. A Lipo pack should not really be discharged below 3.7 volts per cell at resting voltage. This means depending on your amp draw of your system you would want to set a voltage indicator alarm in the 3.5/3.6 volt range. Usually stopping at 3.5/3.6 volts under load after you get the pack out of the quad it will have settled back up at around 3.7/3.8 volts. And if it settles any lower set your voltage alarm higher. My way of figuring out my indicating time to stop is actually approached from the other direction where I'll start by setting my alarm at 3.7 and see where it puts me at resting voltage and figure out what I need to do next outing from the safest healthiest end for the sake of the pack.
I'm not at all trying to be a D in any way but you are in need of some serious research on lipos to keep from destroying your next packs that you miles well go ahead and place a order.
So yes I agree with m Forsyth and have always noticed his post to lead in the right direction.
Jaketheone46 is online now Find More Posts by Jaketheone46
Reply With Quote
Old Mar 23, 2015, 09:14 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,472 Posts
There are some problems here with the data.
1. The quad could not be flying with a pack at 6-8V. Power from a 3s at that voltage would be zip. Second, your charger would not charge the pack after flying at that voltage)
2. The statement that even new batteries give 3 min indicates it's probably not a damaged (from use) pack problem.
3. Was the 2200mah pack added to a 1200mah pack in parallel?
4. Fully charged at 11.2V. That's about 20% charged.
----------------------------------------------------------------------------------------------------
We need some data from you.
Make these measurements with a multimeter. (Even a cheap one is OK. If you are already using one, check it by measuring the voltage of a brand new 9V alkaline cell which should show around 9.5V)

What is the pack voltage after charging?
What is the pack voltage after landing?
hoppy is offline Find More Posts by hoppy
Last edited by hoppy; Mar 23, 2015 at 09:20 AM.
Reply With Quote
Old Mar 23, 2015, 03:39 PM
Registered User
Letchworth, Great Britain (UK)
Joined Jul 2004
12,456 Posts
Quote:
Originally Posted by basnboy View Post
... I do have an unused heavy battery - a tornadoRC 3S 40c but I suspect it be too much for the 30c ESC/motors and it comes in at a weight of 400g itself. ...
Nothing to add to what the others have said about your battery voltages.

But just to add to your learning, the C rating of a battery pack only enables you to calculate how many amps it is theoretically capable of delivering. Provided it's the same voltage, in normal circumstances a higher C rating won't force any more amps through the motors -- the motors will demand only what they want, and that'll depend mainly on the prop size and how wide you open the throttle.

Motors and ESCs have maximum amps ratings, which is not the same as the battery's C rating.
abenn is offline Find More Posts by abenn
Reply With Quote
Old Mar 24, 2015, 09:49 AM
Registered User
United States, WA, Woodinville
Joined May 2014
1,380 Posts
And the C ratings tend to be highly inflated so you generally want to get a pack with double the C rating you think you need.
James_S is offline Find More Posts by James_S
Reply With Quote
Old Yesterday, 12:46 AM
Registered User
basnboy's Avatar
Australia, NSW, Vincentia
Joined May 2014
8 Posts
mrforsyth thank you for the prompt reply, really appreciated.

Your reply and those that follow demonstrate simply I am out of my depth big time on batteries - and rather than assume as I have I need to go back to the beginning. At 52 I am feeling about 5 and should know better. This is the the long learning curve of RC showing itself.

In answer to your question as I note above "....and they are charged slowly with cells balanced on an imax b6 charger". The charger is preset for 120 minute max charge time which I thought was a safety mark..... I usually run the quad until it shows power is starting to fail then stop to remove. On the occasions I get a low voltage - ( I did pick up on youtube how to charge if battery signals 'low voltage' by changing voltage type on the charger for a few seconds - it lifts voltage to charging level and then switch back,,,,,,, - I am cringing now to here the response.)

I clearly need some ear slapping education - one bad place to cut corners as I am finding..
basnboy is offline Find More Posts by basnboy
Last edited by basnboy; Yesterday at 01:10 AM.
Reply With Quote
Old Yesterday, 01:15 AM
Registered User
basnboy's Avatar
Australia, NSW, Vincentia
Joined May 2014
8 Posts
thanks Jaketheone46 I am on the wrong path (read ignorance) I actually thought 3.8v per cell was a max, not a minimum so tat explains a lot as to why I am ummm,,,,, not getting far. And to add to my woes I do not have a voltage alarm but relied on my quads to physically show low power.

thanks hoppy: 1. the 6-8v mentioned is after battery drain, not at its beginning. I will work on your suggestion
2. you sre probably correct it looks like an issue with ignorance (mine) and undercharging
3. no I have not had the pack in parallel
4. I think you may have the primary issue here.

I did read various battery product & information mediums a while ago but in the vast pool of info and of time have forgotten far too much. From a positive perspective, my "enthusiasm" has got away on me.

James S & abenn: thanks also I have said enough to explain what I need to do - I do find the math of sizing up battery use a headache but back to basics first.

This is an excellent forum site.
basnboy is offline Find More Posts by basnboy
Reply With Quote
Old Yesterday, 08:39 AM
Comic Art Collector
DrewC's Avatar
United States, NY, Eastchester
Joined Jul 2013
649 Posts
http://www.tjinguytech.com/charging-how-tos

Check out the info on this site, it's very helpful
DrewC is offline Find More Posts by DrewC
Reply With Quote
Old Yesterday, 10:22 AM
Battery Puffer
Orange, California, United States
Joined Nov 2001
1,167 Posts
Basnboy

I think most people run a 4000 to 5000 mah battery on that size quad. A 2200 would give very little run time.

Mark
MarkF is offline Find More Posts by MarkF
Reply With Quote
Old Yesterday, 09:13 PM
Jaketheone46
United States, KY, Florence
Joined Nov 2014
349 Posts
Quote:
Originally Posted by basnboy View Post
thanks Jaketheone46 I am on the wrong path (read ignorance) I actually thought 3.8v per cell was a max, not a minimum so tat explains a lot as to why I am ummm,,,,, not getting far. And to add to my woes I do not have a voltage alarm but relied on my quads to physically show low power.

thanks hoppy: 1. the 6-8v mentioned is after battery drain, not at its beginning. I will work on your suggestion
2. you sre probably correct it looks like an issue with ignorance (mine) and undercharging
3. no I have not had the pack in parallel
4. I think you may have the primary issue here.

I did read various battery product & information mediums a while ago but in the vast pool of info and of time have forgotten far too much. From a positive perspective, my "enthusiasm" has got away on me.

James S & abenn: thanks also I have said enough to explain what I need to do - I do find the math of sizing up battery use a headache but back to basics first.

This is an excellent forum site.
We all had to learn somehow I was lucky enough to start my Lipo use dead winter where all there was to do is research so I made sure to take in as much as I could and there is still plenty for me to learn as well but I've got most understood clearly. One thing I've noticed is s lot of people think a higher c rating can be to much but your system will only take what it demands from your Lipo c rating wise. Now choosing a pack with too high voltage on the other hand will damage a system quickly.
Jaketheone46 is online now Find More Posts by Jaketheone46
Reply With Quote
Old Today, 12:21 AM
Registered User
basnboy's Avatar
Australia, NSW, Vincentia
Joined May 2014
8 Posts
just not cold enough..............

Quote:
Originally Posted by Jaketheone46 View Post
We all had to learn somehow I was lucky enough to start my Lipo use dead winter where all there was to do is research so I made sure to take in as much as I could and there is still plenty for me to learn as well but I've got most understood clearly. One thing I've noticed is s lot of people think a higher c rating can be to much but your system will only take what it demands from your Lipo c rating wise. Now choosing a pack with too high voltage on the other hand will damage a system quickly.


Damn, that explains everything now, MY winters are not cold enough to stop me being outside - none of that northern hemisphere freeze here- so I have never had the opportunity to hibernate with a good LiPo book under my arm.

Your collective feedback has given me focus now!!! thanks.
basnboy is offline Find More Posts by basnboy
Reply With Quote
Old Today, 09:09 AM
Jaketheone46
United States, KY, Florence
Joined Nov 2014
349 Posts
Quote:
Originally Posted by basnboy View Post

Damn, that explains everything now, MY winters are not cold enough to stop me being outside - none of that northern hemisphere freeze here- so I have never had the opportunity to hibernate with a good LiPo book under my arm.

Your collective feedback has given me focus now!!! thanks.
That's just funny stuf. It's really cool that you took the time to thank everyone for there feedback. Reading mine I kinda sound like a think I know it all. However it couldn't be any farther from the truth and if my feedback seemed rude to you My bad. Although you seem to have took it well even if it did.
The weird thing for me is ever since I discovered Lipos they have became a second hobby for me just wanting to learn everything. I have spent 2 years now researching them and answering questions here on the forum. I never had any intrest in nicad or NIMH but lipos for some reason to me are just really cool.
The past year I have also gotten into LiFe packs. I discovered them watching a redwingrc video on utube. I have absolutely no intrest in ever using any other chemestry for receiver use. When it comes to receiver use they are the best by far in my book. I've never liked high voltage servos so have always stuck with 6 volts for my electronics so life packs are perfect for this.
Jaketheone46 is online now Find More Posts by Jaketheone46
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Where have all the buyers gone? dbc Trader Talk 53 Today 06:33 PM
Discussion All Job Creation Under Obama Has Gone to Immigrants RumRunner_1492 Life, The Universe, and Politics 35 Dec 22, 2014 12:48 PM
Discussion All Of US Employment Growth Since 2000 Has Gone To Immigrants? Big Foot 48 Life, The Universe, and Politics 12 Jun 28, 2014 01:59 PM
Discussion Where have all the75mhz, AM stuff gone??? bigkim100 Radios 4 Nov 14, 2013 11:41 AM
Where has the view all new posts gone???? pda4you Site Suggestions / Complaints 4 Dec 31, 2005 01:17 PM