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Old Apr 27, 2012, 05:26 PM
But will it fly ??
3d addict's Avatar
Ireland, Dublin
Joined Apr 2010
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Lipo run time question !!

Hi guys..

Just bought a few new 1500mah 3s 25c lipos for my brand new yak...
Im fairly new to the electric game but have most setups situations under control.
Now as my understanding goes.. Lipos should be flown a couple of times conserveatly to break them in...

Thats no problem and Ive been doing exactly that... But more recently I've ordered a couple of low voltage alarms that im waitin on.. For my backup I have a Gt voltage analyser that lets me set a alarm threshold of 3.3v per cell..
While this is bulky it will do for peace of mind until its smaller brothers arive..
But now here's the dilema... I would be flying around for a few minutes on lazy throttle and then I hear the alarm so I land the plane..
Huh ?? Ive just been up a minute... So I check the pack voltage on the analyser and the voltage has a lowest cell of 3.3v
I let the pack rest for a few mins while I get another one installed and then recheck it and its 3.9v lowest cell ????
I have 3 new packs and sometimes they lie and sometimes I get roughly 8 mins of conservative flying... what's the deal with the Batts man !!
Is this a kind of issue with newly cycled batts...Something like they take a couple of runs to establish themselves...

Anyway s... Until I get it sorted im kinda half nervous of flying to far away because I had the throttle die on me this evening while I was inverted in a climb about 30 feet from the ground... Saved her but wasn't happy man...

So has anyone been in similar waters before...
Sure love some advise..

3DA
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Old Apr 27, 2012, 05:40 PM
Team Hillbilly (UK)
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Batteries when new can do with bedding in and not being over used for 5-6 cycles...the usual rule of 80% draw of capacity is reduced to around 50-60% for first few runs...

Are you noticing the batteries being excessively warm?
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Old Apr 27, 2012, 05:46 PM
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There is no such thing as a LiPo break in. A cell should have 4.2 Volt when it is fully charged and it should not go under 3.2 Volt per cell. All batteries will gain some voltage by laying around but that doesn't mean they are ready for further use. 8 min is not too bad. If you want more run time get a larger mAh battery. I dont fly mine till the bitter end i know how much they can take by recharging them after the flight and checking the mAh that went in. You also can get a watt meter fairly cheap that will let you know how much mAh you drew out of the battery already.

Hope that helps.
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Old Apr 27, 2012, 05:52 PM
But will it fly ??
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Ireland, Dublin
Joined Apr 2010
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Yo Space !!!

Ok cool.. Yeah I'm trying pretty hard not to fly them on too hard...
But Im getting crap flying times... Sometimes.... Sometimes not
For instance today I ran the 3 of them and only 1 gave me a confident 8 mins.
Funnily enough ive been keeping my eye on this particular battery because one of its cells is almost .2 of a volt below the rest...
Sumthin like lets say ... 1st cell 3.9v 2nd cell 3.6v 3rd cell 3.9v
But that's the only battery that gave me flight time today..
The rest just beeped and beeped...
Yeah I checked the temps.. But zero puffiness and almost zero temp rise in any of the 3...
Even weirder is that lets say I get a beep to come back to earth.. I instantly have a look at the voltage and its where expected for the given flight time, but yet the alarm is goin off and its knowhere near the 3,3v threshold.

Bahh I have it down the fussiness... They better loosen up and start having some fun
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Old Apr 27, 2012, 05:57 PM
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What kind of charger do you use and do you ever balance charge your LiPo's and if so at what rate
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Old Apr 27, 2012, 06:12 PM
But will it fly ??
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Ireland, Dublin
Joined Apr 2010
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@mkosirog

Honestly Im using a cheapo charger while Im waiting on a proper balance charger to be shipped.
This one has just a set of balance plugs ..No battery plugs..
Its actually not bad in my opinion... Not heavy duty but acceptable..

Charge is a little Blue Mystery Balance charger
Lipos are 2x Mystery 1500mah 3s 25c
1x Aku 1500mah 3s 25c


I charge it at around 1.5c and don't mind the wait...

The packs seem to balance up pretty well.. But then We have the one I keep my eye on..Which rember is the only performer today... That goes off sometimes by .3 of a volt
But when I charge it it sits at around .1 of a volt off...

ITS not the GT analyser at fault I don't think.. Because yesterday I didn't use it and the esc kicked in at around the same 3.3v per cell
But same issue there... After a few mins resting.. I find out I could have flown for another 5,6 mins
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Old Apr 27, 2012, 06:38 PM
But will it fly ??
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Ireland, Dublin
Joined Apr 2010
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Hah... I did a little check there just now...

The aku pack that performed today is waay off..
S1 3.69v
s2 3.16v
s3 3.50v

the other two fussy Mysterys are
3.80v per cell each Minus a few deviations on the last digit..
They look pretty acceptable I would imagine..
But they did Jack $%*t today only complain..
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Old Apr 27, 2012, 06:45 PM
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Here is what you do. When you get your proper balance charger you discharge the LiPo's and then balance charge them @ 0.5C ... After that they should work perfectly fine. IF the ESC and the battery stay cool than the amp draw should not be an issue. If it would both should get warm.

Just while you are at it you might want to check the wiring in the plane too.
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Old Apr 27, 2012, 06:47 PM
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3.16 is below recharge point. Your charger won't let you charge them anymore. You will have to force charge them to 3.3 and than go from there.

Are the others 3.8 after charging? IF so your charger or your batteries are done because they should be 4.2 per cell
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Old Apr 27, 2012, 07:15 PM
But will it fly ??
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Ireland, Dublin
Joined Apr 2010
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No No... what I meant is I just checked them static... No recharge... And there 3.8v

Back at the field they were crying and wanted to come down.. And sure enough at least one cell had tripped the LVC .... But again no more than 3 mins later they were up to 3.6 or around
Now there 3.8 Which I totally believe because they didn't fly for more than 5 mins...No 3d only gentle break in...

When you say discharge them I think I wont be able to achieve that with what I got ??

http://www.hobbyking.com/hobbyking/s...dProduct=14633

I know I know... Youre a cheapskate... But Honestly Ive just gone down the electric route and have shelled out 400bucks already on equip and new plane... I figured ill step up in quality as I progress
This is a trial run so to speak...

BTW I just plugged in that dodgy Batt to the charger and its charging as we speak..
I will keep a close eye on it and check the V in a few mins..
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Old Apr 27, 2012, 07:20 PM
But will it fly ??
3d addict's Avatar
Ireland, Dublin
Joined Apr 2010
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Just a thought... I dont know obviously all the tallies with the esc's and there settings just yet..
But is it possible that the timing is off or something...
I have it set at medium because I cant tell how many poles the motor has...
Its a brushless art tech Geared Inrunner... Crappy but im gunna run the gears off it until I put in the Hexitronic dt750 powerhouse..
But obviously no point if the stock is giving up the ghost after a few mins..
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Old Apr 27, 2012, 07:30 PM
But will it fly ??
3d addict's Avatar
Ireland, Dublin
Joined Apr 2010
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yeah there's something well fishy happning !!!

I have that dodgy battery charging at 1c for the last 5 mins at it has just jumped to
s1 3.75
s2 3.67
s3 3.71

Now that to me looks like either it was telling lies and actually the cells rested similarly
or the charger has magicaly balanced the wierd cell pretty darn quick..
Rember heres the resting voltages of that batt no more than 10 mins ago
S1 3.69v
s2 3.16v
s3 3.50v

Scratches Head yet again !!!!
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Old Apr 27, 2012, 08:42 PM
Not failing=Not trying enough
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United States, IA, Coralville
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I think you could do with a little more information on LiPo batteries, so I'm going to explain some of the basics.


A fully charged lithium polymer battery will sit at 4.2V per cell, or 12.6V total for your 3s.
A resting, fully discharged lithium polymer battery will read 3.7V per cell, or 11.1V total for your 3s.

During flight when there are loads on the battery, its voltage will drop. Example: The LVC(low voltage cutoff) trips at 3.3V per cell, but after landing and sitting for a few minutes, the battery might raise to 3.6V per cell, which is still lower than I would prefer, but will be fine.

Your batteries seem highly out of balance. I aim for no more than 0.05V difference between the cells. It's also important to know how the majority of chargers balance multi-cell batteries. It will push current through the two ends of the batteries until one cell reaches 4.2V. It will then discharge only that one cell some, and then charge all cells again. It will repeat this process until all cells reach 4.2V at nearly the same time.

It appears that in that "dodgy battery", the second cell has a reduced capacity, which makes it drop voltage sooner than the others. If it were me, I would wait until your good charger comes in, do a full balance charge, then discharge and watch the individual voltages. If one drops significantly lower, I would trash the battery. It's not worth risking over-discharging or over-charging your batteries to save $15.
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Old Apr 27, 2012, 09:11 PM
But will it fly ??
3d addict's Avatar
Ireland, Dublin
Joined Apr 2010
181 Posts
Story Wehdro...

Thanks for the advice man...

Im a fully Q Electrican.. So Naturally I respect Electricity and its laws... Thats why I prefer to head to a watering hole and gather info from the regulars before I head out into the unknown.,
On the plus side it doesnt look like Ive damaged anything yet and general rules of thumb have been applied..
What Do you make of this breaking in period...I see some people suggest... !!!
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Old Apr 27, 2012, 09:53 PM
Not failing=Not trying enough
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United States, IA, Coralville
Joined Jun 2011
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It's good to know I can throw around electrical terms and not lose you

I don't think a breaking in period is necessary for LiPo batteries. On NiMh and NiCd batteries that have been used before the advent of cheap LiPos, a few full cycles will maximize capacity. As far as I know, Lithium batteries(Polymer or Ion) won't gain any capacity from running full cycles. Actually, it's recommended not to drain completely for longest life. Nickel-based batteries suffered from what's called the "memory effect" where if not completely drained each time, they would lose capacity. You can look that up for the chemistry behind it, if you're so inclined.

Mind linking to where it's suggested to break in LiPos? There's a lot of good, accurate information on these forums about batteries, but there is quite a bit of wrong info out there too.

About the runtime mentioned previously. On a 3D machine like a Yak, eight minutes isn't a low run time. You could for sure increase capacity and get more time, but your performance would suffer greatly. It's better getting multiple batteries that you can swap out.
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