How many mA do you put back in lipo?

[ched]

I';m a noob so learning, sorry. I have the Hobby King x120 charger that tells me how many mA it has put back in the lipos but it doesn';t tell me how much it pulled back out in balancing!

Ultimately I am trying to work out lipo alarm levels on load so when the batteries are rested they recover to a sensible voltage.

Currently I have Turnigy 2200mAh 20C 3S and Zippy 1800mAh 25C 3S but the charger seems to be putting a total charge, not taking balance current removed into consideration, of virtually the lipos capacity!

So does any one know how much mA is likely to be pulled out to balance or what their charger states it has put back in the lipo?

Cheers.

[jammienew]

hi, i have turnigy nanotechs 1300 and i drop the voltage down to about 3.7 after a flight ( resting voltage with no draw, can usually go down to 3.5-3.6 when under load) on a balance charge i end up putting in 1100-1180 mah, but i guess thats because on a balance charge it discharges cells and charges until balanced. On a straight charge it works out to be 80% of mah, about 1000 or so. hope this helps. i usually balance charge, just habbit i suppose.

[nub]

it has a touch screen but doesn';t show you how much mah it puts into a battery 

sorry probably not much help.

[kilby]

To be honest the number of mAh dumped during a balance charge isn';t too significant probably more lost due to inefficiency in the charger etc

[Friskle]

personally, i dont get that technical, i charge my battery, fly for the alotted time, land, take battery home, and dump it on charge till it beeps, job done :)

[ched]

personally, i dont get that technical, i charge my battery, fly for the alotted time, land, take battery home, and dump it on charge till it beeps, job done :)

The problem I have is working out the allotted time when I am learning, have new kit and zero experience! 

[kilby]

It was keeping an eye on the power put back in showed that either the charger was badly wrong or the voltage checker was.

Turns out the battery checker was giving a value between 25% to 30% lower than it should have been.

About 4% out when the battery was fully charged so it wasn';t as easy to catch as you would think

[xxpitt]

I usually put in more than it says it has. But my lipos don';t last very long

[ched]

I usually put in more than it says it has. But my lipos don';t last very long

How long is not long? I would be surprised if I can get out on average twice a week not even considering winter etc. So if my batteries lasted me a year (season) it wouldn';t be too bad.

[xxpitt]

Well I';ve not had lipos last my more than 6 months. But I';ve had some go in under a month and one go in a week. Sometimes I';m flying them till they drop out the sky. Then I';m putting something like 2200mah back into a 1800mah lipo. Obviously some of that is balancing. I';m trying to change my ways but I just get a bit carried away.

[gb0wers]

You raise an interesting question about mAh consumed during balancing Ched and not one that had even crossed my mind before. My instinct is to go with Kilby who believes it probably doesn';t matter.

My regime is to land when I get down to 3.6V per cell, which then gives a recovered value of 3.7V - a lot of people seem to use these numbers. What I learned yesterday is that as flying techniques change (in my case FPV in windy conditions) I dragged more out than I wished, as it took longer to land than usual.

Overall I think you are doing exactly the right thing,  developing a system of LiPo monitoring and care that suits your aspirations of flight and LiPo life expectations.

Do remain alert to other factors. For example, as your LiPos age, they will have less capacity and usually take longer to balance, but you will see that trend develop. Also, ambient, and so LiPo temperature can make a big difference and not be spotted in a trend. If flying in cold ambients (hopefully a long way off), try to keep the LiPo';s warm before flight, and don';t expect to be able to take as much out - but my winter flights are often cold finger limited anyway. Finally you may expect to see variation between brands - and potentially C ratings within a brand. I';ve been using Hayin 20/30C 3C 2200';s for about a year but just got some Turnigy 25/35C 3S 2200';s. First impression is that the post flight balance of the Turnigy';s is not as good and the Hayins. I need to be more diligent and keep records.

Hope this helps

Graham

[Nic]

Sorry for jumping on the thread. But, people are on about balance charging?

When my batteries are low, i just put them on charge. There is a balance option. Should i be balancing them or just charge?

[xxpitt]

I 1c balance at home 2c charge at the field or some tomes ill just put it on 6a fast charge (that';s the most my charger will do) just to get back in the air again. If your lipos come down warm you should let them cool before charging

[jamesb72]

I';ve always flown to timer (triggered by throttle stick so it only times actual motor running time), and I adjust based on mah recharged - not every pack, but if I see I';m close to 80% I drop timer 30 seconds.

Resting voltage after flights is generally around 3.7v, but as flights vary and packs do too, its not exact, I tend to be conservative on flight time, and hope that I get more cycles from packs - I';d rather fly 30 seconds less and get double the cycles from a cheap lipo.

Typically on the 250 quads I am flying with timer set to 5m30s, if I';m just flying around I will go right up to this and then fly back, so total flight is probably closer to 6mins, if I';m racing then I will normally stop at the 1min remaining voice announcement as this is generally much harder on lipos. I also have the voltage alarm set on naze32/KK2 so if I hear that I know to land immediately as either the pack is going soft or I forgot to reset timer (easily done).

If a pack comes off warmer than normal it generally indicates you';ve gone too low, a lipo checker is really useful (and cheap as chips on ebay) these ones show both the voltage and a rough % of pack status which is really useful. I look at both the cell voltage and spread from highest to lowest - click mode button shows you this and the highest/lowest cells (generally as packs age the voltage difference between cells will go up under load).



The best way to check packs I find is to check voltage after 30 seconds on a decent load - say 10Amps, as packs age they will not hold voltage under load, also the spread from strongest/weakest cell will really increase, so then you know to retire them or use them for running goggles/vrx etc where they will be fine.

I check my packs at the start and end of the season, and jot down voltages under load on light bulbs after 30 seconds, so I can ditch the weakest ones and order replacements.

[Panther]

Sorry for jumping on the thread. But, people are on about balance charging?

When my batteries are low, i just put them on charge. There is a balance option. Should i be balancing them or just charge?

Nic, years ago chargers didn';t have a balance feature but now most do.
It is an important feature on a LiPo charger as cells can get unbalanced. This can shorten the life of a battery considerably over time.
They do not have to be balance charged every time but it is good practice.

[kilby]

Sorry for jumping on the thread. But, people are on about balance charging?

When my batteries are low, i just put them on charge. There is a balance option. Should i be balancing them or just charge?

Over time the individual cells can get a little out of balance and if you are doing a regular charge this difference usually gets worse over time.

You can balance charge, which is where you connect the balance lead to the charger as well and it can track the individual cells, and get all the cells to the right value.

The GNZ (Grumpy New Zealander) aka Bruce has several videos on this subject.

Although he is long winded and can go off on other subjects there is really decent info in there, if you haven';t already checked the channel out have a look http://www.youtube.com/channel/UCahqHsTaADV8MMmj2D5i1Vw

[Soler]

I always try to fly so that when I charge I put 80% of their stated capacity back in.  I use this to adjust my cut of voltages when I should stop flying.

[Gatallica]

Not quite sure what your asking, but my advice is to keep it simple. I always leave around 200mah margin when charging to conserve battery life and not overcook the cells. So for a 2200mah, I charge at 2000mah and so on. I always balance charge.

[Paul01]

As above, I try and leave a few 100 mah in my packs, but also increase this if I have packs that suffer from voltage sag like my 3700mah 3s zippys which I aim for about 500mah left.