detect drop below critical voltage for lipo

[glenn cain]

i run on brushed with my new kokam 1200

juz wondering, is there anyway to detect or deduce whether the lipo has gone below its critical voltage once or more before in its lifetime?

[HZM]

I was told u should stop even b4 yr heli goes into ground effect....


But I bo chap.......that why my cell not powerful nowadays.....


Mike

[Fit]

Somebody here rich sial

Anyway, for me I stop when I find that I have not much more reserve left to climb out. When I used lipos on my Feda, once throttle response gets soft and at full throttle the heli doesn't climb much, its time to land. You should get around 15 to 18mins of run time with a 1200 pack.

BTW Glenn, where did you get the Kokams from and how much?

Thanks!

[PhiBeR]

Hmmm.. wanted to ask this question too..

Is there a recommended stop voltage?
I heard it's arnd 7.4v for a 2S pack?

And NEVER below 3V per cell else u have to do trickle charge
or u will risk imbalancing the cells?

FYI, i heard from derrick saying that he and loyn are
quite sure the local 1500s are NOT kokams and some cheap ripoff!!
Very bad quality and die easily..

[glenn cain]

you mean the 1500 that are on low offer at one time, or just general?

my 1200 kokam are from the "that hobby shop" the new shop.
42 or 45, i forgot. i also stop flying when i see my heli getting an unsually mediocre lift rate at full punch

but i really wanna be sure


by the way, how much physical knocking can a lipo take before the performance of the lipo deviates from perfect? let exclude stabbing it with a knife (duh), coz i've flying outdoors with low wind condition, and besides the usual hover routine which give 2m of height and potential energy in the crash, i am giving it about 10 to 20 km/hr when i lose control, lipo is mounted at the front due to balance (temp config), no canopy. hope i dun scrap it up again like my last lipo.

[Tele]

I have sen a voltage cut off at champion the other day but dont know what voltage.

[loyn]

There are several sub-micro LED product in the market (US) that help to provide indication on the LIPO voltage. The turn on when the overall voltage drop to 6V for 2S cells pack. There are several other design for 1 (mainly for sub micro indoor plane using single cell) to 3 cell respectively. They are very samll and light (<1g) cost slightly more than US$10. It will be good to have them to prevent over discharge of the lipo battery.

[loyn]

Attached is the photo of the voltage monitoring device approx 270mg for US$8

[D.Yeo]

looks good loyn where can we order those from ? where do they go in the circuit ? across the battery i'm guessing ?

[HZM]

Loyn, please provide link ley

I am not rich lah... I too is ignorant, if I got new pack, I will not discharge all the way lah

Maybe we can do a mass order for such a stuff...... I had posted a request thread at RC electronic category, see if they can help us find a circuit which we can DIY

Thanks Xiao ma and Ducky in advance

Mike

[FDC]

Think this is fairly straightforward to do... just need an op-amp voltage comparator, a flip-flop latch and an LED. So once the battery voltage under load hits below the recommended Lipo cut-off voltage, the LED will light up and stay lit even if the voltage has already gone up again. The problem with any DIY is the size and weigth and the unprofessional look of the finished product unless you have to use SMT components but you have to have the proper equipment to do so.

As using Lipo is already investing a huge amount of $$$ for batteries, think the best way to go is to invest some more $$$ in Lipo compatible ESCs' to maximize lifespan of your investments.

For BL, I'm very sure that CC Phoenix 10 or 25 already has a Lipo LVC setting. For Brushed motors, there is the Pixie 7 or 20 which has a Lipo LVC setting.

[gregw]

DIY Lipoly Low Voltage Detector Circuit here.

Refer to this thread for the discussion.

[MicroHeli-Nut]

Yo gregw, welcome to the Board!

[loyn]

Following is the link where you can get it

https://www.homefly.com

but is out of stock for the moment, will try to locate another source while some of you can try the DIY version.

[gregw]

Originally posted by MicroHeli-Nut
Yo gregw, welcome to the Board!

Thanks.