80% Rule?

[ShotgunTC88]

Man I am stupid......That said, Can someone please tell me what the hell the 80% rule is and how to do it?

What I have done that I don't quite think is right:

Charged to full (2200 Lipo 11.1 volt batt. on Triton set correctly (1amp,11.1 volts,...1amp for batt. longevity?)

Then I run the Heli to cutoff (3.1volts soft cuttoff) and did not run after landing when cutoff started.

Now how do I know I if I only am using 80% of my battery when I charge it back up to full charge?

I am trying to understand what I have read is that you charge the batt. and see how much charge mah. you put back in after a flight.

I useally see that I have put at least 1600/1900 mah. back in when the Triton shuts down.

I am lost please explain or point me to a post for dummies :arggg:

Thanks
Billy

[noguy]

My Thunder Power charger literature says that lipo's should not be discharged below 3.0v. Many other folks out there say to stay above 3.2v per cell. I keep mine above 3.2. I dont think the 80% i as important as staying within safe voltage range. 4.2v is maximum. I could be wrong on this I am no expert but I dont think you need worry to much about 80%. It is probably just another good guideline to follow.
Someone more knowledgable may know more about this 80% thing.

[Jafa]

NEVER fly a heli until cutoff
The voltage cut off's are not able to cope with high drain and quick drop off
You're probably ok as this is a lower level current drain

1-Charge the LiPo
2-Use the charger to discharge the LiPo - record how much came out
3-Calculate 80% of how much came out - this is how much you can use in flight
4-Charge the LiPo again
5-Fly for a safe amount of time
6-Charge the LiPo again - record how much was put back in
7- Compare how much was put back in to what was calculated at step 3
If you are below the figure step 3 figure then you can fly longer
If you are above the step 3 figure then you must shorten the flight time

You need to repeat this every year - as the battery ages it's capacity reduces

You need to repeat this periodically (say after every 50 flights)
cos the capacity reduces with high discharge usage

[noguy]

great info thanks....

[ShotgunTC88]

Thanks Jafa, (and noguy)

Makes perfect sense to me now that it's not in Greek!!!......LOL!

I appreciate the info and will follow it, I already balance the cells and check em pretty regular,(heat over 104,charge in a safe place, etc)

The way you explained it is crystal clear!, Dam all the other methods seemed like I needed my daughters science calc to figure it out :mrgreen:

Thanks again
Billy

[Powrplay3D]

ShotgunTC88

Since I started lipos, it took me a lil while to understand the 80% run as well. I am a rebel and thought I always will be because I learn the hard way with this hobby. After burying several lipos, the prices on new packs was starting to catch up to me and since then, the 80% rule was in full effect.

UNTIL

...after keeping an eye on (thread) a lipo you can NOT puff from over discharge, and will allow me to go to cutoff, if I wanted to.

I soon purchased a couple packs, arriving at my door two days later. I've been flying these new lipos from AirThunder and to make this short, I'm back to being a rebel :twisted: I've since put over 45 cycles on both packs and they're still going strong!

www.airthunder.com

Errol

[EricW]

I managed to get a 6 minute flight ( pulsing ESC) out of the Airthunder pack.
forgot to charge it!!.... and was wondering why my ESC was acting so funny :arggg: :mrgreen:
really stupid actually.
Charged it afterwards without a problem,.
Pretty sure if this happened to one of my other lipos i could have thrown it in the waste bin.

Eric

[Pinecone]

Mcuh easier way.

2100 x 80% = 1680. So if when the Triton ends the charge, it says yo have put back less than 1680 mAH, you have run the pack down to less than 80%. If you put back more than 1680 mAH, you have drawn the pack down to far.

If you hit cutoff and still don't put back in 80% you are over drawing (too high C) the pack, or if it has a bunch of cycles on it, it is starting to lose capacity.

[Hughes500Bob]

Charged to full (2200 Lipo 11.1 volt batt. on Triton set correctly (1amp,11.1 volts,...1amp for batt. longevity?)

Since no one answered this ..... Charge at 1C which is 2.2 amps for a 2200mAh bat.

1 amp for 1000 mAh bat, .5 amp for 500mAh bat ..... see the pattern here!

Some bats can be charged at higher C ratings .... so go by the manufacturer specs!

If you are balancing and charging at the same time, you will use more mAh than just charging depending on how balanced the packs are prior to charging and how well balanced the packs receive their voltage.

Note .... Some chargers charge through the balance tap (BalancePro for example and I think CellPro) and they use a higher C rating than 1C because they are charging and controlling each cell individually.

[ShotgunTC88]

This sounds nuts, but check this out :shock:

I have an old (1yr or so) Polyquest 3C 2200 10C....Yes a 10C!, And I was using it as a "test battery" i.e, setup controls,yada yada....

Anyway I decided to hover around on it to see if it would actually have enough ommph, And the dam thing actually flew the Dragonus stocker for 11min!!!

AND.....NO Heat at all! (104deg) of course if I could do 3D I am sure I could have made a neat fireball outta the Dragonus :lol:

I was kind of under the imppression that 15C was as low as we could go on a high amp draw bird like a heli :?

Weird or not?

Billy

P.S, Thanks Pinecone, For makin it eve easier for the mathmatically challanged :glasses2:

[skunkworx]

I've always gone on the rule of keeping my packs above 11.1v no matter what. When I balance charge on my Triton, mAh's usually come out around 1400-1600mAh. A few times I went over and my recharge went above 1680mah and my batts are kinda starting to lose their capacity. I use the TP 2070's and 2200's so I'm not sure why my packs are doing so badly. I'm lucky if I get about 5:00-5:30 out of my flights.

I've been wanting to try the AT's for some time now, but have been grounded due to surgery. I sure hope they fix a lot of the problems I have with Lipos. It'll really help with the hobby all around if every manufacturer can get onboard with this new technology!

[PDC]

Just remember that 4.2V and 3.0V are not targets but should be looked at as limits...the longer away you can stay from these, the shorter flight time and longer battery life you will have :-). So 80% is to be looked at as a good thumb rule and as a good tradeoff between flight time and battery life.

Many of the new chargers can be set to have a end charge below 4,2V each cell like the Newest update for Orbit chargers and the PowerCube charger.....I like to charge to 4.15-4,17V end charge each cell in order to have a small buffer to the limit. (a end charge to 4,15V -4,17V is equal to app. 95% - 97% fully charged cells)
And the idea is that the battery life should be extended by more than these 3-5% reduced flight time plus the chance for a overcharged individual cell is significant reduced when charged without balancers attached, from small to very small with a well balanced and maintained battery.

Especially if you charge with more than 1C and therefore approach the 4.2V limit at "full speed", I find it useful to be able to reduce the end charge a little below the 4,2V limit, as any small differences the cells between grows the "faster" you go. (important to remember if you dont charge with balancers each time)

I calculate the 80% with refill compared to nominal capacity...just remember that nominal capacity is only valid on new cells, so with age the 80% should be reduced to a 70% rule after maybe 100 cycles as a thumb rule.....depending on many factors ofcause.

If you set the timer on your transmitter to beep after the time equivalent to 80% used capacity with a flying style in the "hard" end, then you have a conservative timing where you in your head can add another 20 or 30 seconds if you have only made "mild" flying.

And finally.....many forget that the less they discharge, the less they have to charge again ;-)

[kgfly]

This sounds nuts, but check this out :shock:

I have an old (1yr or so) Polyquest 3C 2200 10C....Yes a 10C!, And I was using it as a "test battery" i.e, setup controls,yada yada....

Anyway I decided to hover around on it to see if it would actually have enough ommph, And the dam thing actually flew the Dragonus stocker for 11min!!!

AND.....NO Heat at all! (104deg) of course if I could do 3D I am sure I could have made a neat fireball outta the Dragonus :lol:

I was kind of under the imppression that 15C was as low as we could go on a high amp draw bird like a heli :?

Weird or not?
Not weird. 3s 2200 10C => 22A continuous. Hovering a Dragonus should be in the 8-14A range. Say 12A (which is 5.5C) => 60 * 2.2/12 = 11 minutes. Certainly you need a higher C rating for anything much more than hovering or very gentle FF, but for the low-power pottering around the 10C battery will do fine and should not even get more than a little warm.

[EricW]

I've been wanting to try the AT's for some time now, but have been grounded due to surgery. I sure hope they fix a lot of the problems I have with Lipos. It'll really help with the hobby all around if every manufacturer can get onboard with this new technology!

I really hope for Airthunder they have copyrighted/patented the whole concept very well, so they can sell concept-licenses to other big manufacturers .
It brings a little extra weight(great for the COG on my MT), but the Lipo's do what they promise.
The way I fly, it makes no difference if i use a FP EVO25 or the AT.
With the great feature of being able to fly it till the ESC stops it at normal discharge cutoff without any worries, and the no worry factor means a lot to me apart from longer flight times.
What 80% rule???, Great Lipo's IMO!!

Eric

[skunkworx]

Sweet! I'm really looking forward to getting them! Thanks for the info