Lipo battery brand choice

[David Molineux]

Another vote for Gens Ace here. I've been using then for about 4 years and they're great. Admittedly, 4S is as big as I go.

Dave.

[Bravo Delta]

Posted by Cabbage Man on 01/06/2016 18:25:55:

Some years ago , i read about an idea to gently puncture the lipo to relieve the puffing gas. I did it once but had to wear double bicycle clips to do it and even then wasn't totally comfortable .

Is this feasible and what exactly happens when a cell puffs?

This is not a good idea , I would strongly advise NOT to puncture a puffing Lipo cell .

[Erfolg]

I would not be happy purposely puncturing a Lipo bag/wrapper. I have seen a club member driving a nail throgth a Lipo. Nothing actually happened, other than the dying Lipo was probably finally dispatched.

My reasoning is, if it were desirable, one or two of the manufactures would be supplying them in that condition.

My other reason is, my understanding is that the carrier and catalyst are produced in a totally inert atmosphere, that the active parts are inserted into the wrapper in an inert atmosphere. My guess is to stop any oxidating reaction, in the assembly. It is then welded/sealed to maintain these conditions.

All of this is to some extent supposition, as I do not know what is the electro chemistry is. Although I guess it does not include oxygen and all the other gasses in the air.

My own guess is that the puffing of any cell suggests that the reaction has generated a gas. If on charging it does not disappear, it suggests to me that the process has not been reversable and that with time theire is less of the active original components to do their magic. It is the entropy in the cycle we can see and feel.

[Shane Sunday]

I've used 2s 4s and 6s turnigy lipos. Ran them as 6 in series 8 and 10s. So far they are cheap as chips and offer better results in my EDF setups.this is what I like to measure by.

Nano tech lipos are crap! Dead cells, wont ballance and puff up. Only just recently purchased them to try. Spent too much to be let down.

I've a few 3s gens ace 2200mah now for a few years and I like them still.

Ive been looking to find a quality lipo for large EDFs and it sounds like the turnigy might just be the best choice. I guess stick to what works.

[Simon Chaddock]

The puffing is apparently caused by the cell starting to break down. It is an irreversible process.

A puffed cell is weaker (less capacity/higher IR) than a non puffed cell so in a pack it is likely to suffer a deeper discharge and further degradation.

Releasing the gas will make no difference to the cell's performance and the danger in puncturing it is that air (oxygen) might get in which could well lead to a 'runaway'. Guess how i know this can happen!

[Engine Doctor]

Posted by Cabbage Man on 01/06/2016 18:25:55:

Some years ago , i read about an idea to gently puncture the lipo to relieve the puffing gas. I did it once but had to wear double bicycle clips to do it and even then wasn't totally comfortable .

Is this feasible and what exactly happens when a cell puffs?

DONT puncture the pack! A. Few years. Ago I witnessed a flyer removing a battery from a model  with the aid of a screwdriver ! He had fitted a slightly larger than recommended pack and had flown it until it had puffed slightly and it had wedged in the fuz . While he attempted to pry out the battery with a screwdriver ,we  were all advising him not to do it , he punctured the pack . A slight crackling noise accompanied by a cloud of gas came from the model. The owner immediately dropped it and we all watched the foam model melt into a puddle of burning foam. The owner was very lucky not to have been burnt. It was comical to watch and we all had a good laugh at his expense but it was a good lesson in how not to treat your batteries.

[MattyB]

There is surprisingly little about what the actual chemical process is that cause swelling - according to Battery University (my go-to info source for all battery related questions) the cause is hotly debated by manufacturers. I did find this explanation on another forum that the gas is oxygen which (as a rusty ex-chemist!) does seem a lot more likely to me than the hydrogen often proposed, but there is nothing else I have found online to back that up. You be the judge...

"The typical cause of puffiness is either age, or abuse (or a combo of the two.) As the cells are used, the anode naturally degrades, producing oxygen and leaving the Lithium and other element in a useless state. In addition, as usage goes along, the cathode slowly starts to produce metallic lithium. The oxygen produced by the anode bonds to the metallic lithium produced by the cathode, again limiting cell usability, and creating lithium "rust." However, the anode produces oxygen faster then the cathode produces metallic lithium for it to bond to. This means that the oxygen has nowhere to go, and pressurizes the cell, making it puff out. This is also one of the reasons an overcharged cell will ignite under water without the presence of oxygen and air. Also due to lithium being HIGHLY reactive with water."

Edited By MattyB on 07/06/2016 11:05:49

[Cuban8]

I find that standard Turnigys or Zippys are fine. Largest batteries that I use at the moment are Turnigy 3000 6S packs in my Hyperion Helios - massive vertical performance if you want it delivering 1400W at around 60A. Packs are three seasons old now and are used regularly, no sign of puffing or significant loss of performance.

Zippy compacts are also very good, but I agree that Nanotechs do seem to be prone to puffing even when running them well within their limits.

Edited By Cuban8 on 07/06/2016 10:50:30

[Erfolg]

Just as many other modellers, I have read a few articles which discuss Lipo batteries. I will not pretend to understand much of the discussion with respect to the electro chemistry.

There have been a few things which i did learn in chemistry, one is that most if not all reversible chemical processes are 100%. Hence with time even th perfect charge and discharge process leads to some differences. From memory this is part of the general entropy of the world, all tending to disorder. It does seem that some batteries are better than others at this process.

The other aspect which seems to be true, is that there is some variations in the chemistry and make up of Lipos, dependant on the intended usage and general product development.

I still have difficulty with the concept of the massive fires. As many of you will remember whwn in the school chemistry lab, that the highly reactive metals were kept in a test tube, covered with a oil to prevent contact with moisture in the atmosphere. You were then instructed to take out a small piece, about the same quantity as in a Lipo, stick it in a Bunsen burner, and another piece into water, The reactions were pretty impressive, although not on the scale of needing the fire brigade or even a fire extinguisher. I do believe at present that a lot of the reaction is probably the wrapper, and potentially some of the components other than the Lithium.

I do think that there is some danger from Lipos, as there is with Petrol, and Cadmium and many other things. Yet the real problem with any item is appropriate handling. You would never put a naked flame over a bath of acid when a metal is immersed in it ( say a Pb car battery).

Edited By Erfolg on 07/06/2016 22:52:29

Edited By Erfolg on 07/06/2016 22:53:06

[Dave Bran]

Posted by Erfolg on 01/06/2016 18:14:01:

It seems we all have issues with Nanotech and puffing.

No, we don't!

[Dave Bran]

**LINK**

[Erfolg]

Dave

It is heartening that some one, I guess yourself have had good experiences with Nonotech.

On the other side it does seem a number of us have experienced issues, in my case puffing. To date i believe I have have purchased 3 packs. In the first instance putting my experiences down to bad luck.

It would be most interesting to have an idea of how many who have followed this thread have used Nanotech, how many have used them without issue and the number with issues.

The link is most interesting, for a number of reasons.

The first area of interest was that deliberate short circuiting did not cause a runaway reaction.

The second was that the fire with a Lipo was initiated by the package splitting open in its entirety. This may explain why some have managed to drive nails and other objects through them without any issues ensing. In my opinion a rather stupid thing to do.

The other iteresting issue seems to be, from my interpretation, that an external heat sauce was required to start the reaction.

As I have previously suggested, i would have expected the high intensity part of the fire to be of a very short duration.

What i had not expected is that there was still sufficient reactive materials present to re-ignite the package albeit resulting in a lower temperature fire.

Contrary to a number of opinions, it does seem that a Halon fire extinguisher does put out the fire. Although it did seem that determining when a cell had reignited was difficult to determine due to the test chamber size.

It did seem that the number of Lipo cells used as a package was much higher than a typical pack we use. I should have checked, to obtain a better perspective of the scale of the test, with respect to us modellers.

I am left with impression that there reassurance was obtained that the fires were not started by short circuiting of the Lipo packs and that a external heat source was required to thermally degrade the cells.

[Cabbage Man]

I use only nanotech in 3-10  cell set ups .I cant recall any puffing and only 1 out of 30 was a dud. Superb punchy power right till the end of a pac.

Low 1/2 a charging and reasonable discharge rates below 10c seem to be working.

 

Edited By Cabbage Man on 08/06/2016 13:32:05

[MattyB]

Posted by Cabbage Man on 08/06/2016 13:30:18:

I use only nanotech in 3-10 cell set ups .I cant recall any puffing and only 1 out of 30 was a dud. Superb punchy power right till the end of a pac.

Low 1/2 a charging and reasonable discharge rates below 10c seem to be working.

If you are only using them at discharge rates below 10C then you are not a typical buyer of Nanotechs. They are marketed specifically for high power setups requiring rapid discharge rates (EDFs, pylon racers, hotliners etc) so that is how most buyers will use them; that's also the usage pattern that seems to be seeing them puff after a relatively short number of cycles in many instances. I only bought one pack to test which did exactly that despite me caring for it meticulously, and I know plenty of other people who have had the original Nanotechs puff in short order and will not now buy them.

[Bob Burton]

Posted by Erfolg on 08/06/2016 12:10:40:

It would be most interesting to have an idea of how many who have followed this thread have used Nanotech, how many have used them without issue and the number with issues.

I have 6 3S 1300maH Nanotechs that I use on a 250 and slightly larger multirotor and have had no problems. I have the transmitter set to warn of low voltage below 10.5 volts and land soon after it warns. The lipos generally recover to about 11 volts when disconnected and I am meticulous at putting them back to storage voltage after use with a balance charge.

The lipos are not used in a strict rotation but are picked from the 'fridge at random for charging.. Any not used or partially used during a flying session are returned to storage voltage unless I am going to use them the next day. Like all such regimes I sometimes slip and don't put them back to storage voltage but I keep any charged packs to one side they usually get used again with a few days.

As someone said earlier in the thread you will hear good and bad stories about any/all brands of lipos. As they say, Your Mileage May Vary.

[Erfolg]

Bob

I had been led to believe that it was not desirable to store Lipos at low temperatures (most fridges being set to about 4 deg C). I guess that you store in the semi discharged/storage voltage. My understanding that if stored when at max capacity it was the temperature drop that could cause the lipo to exceed the max voltage as when charged at ambient. Not being an expert, the views of some informed people would be useful.

Again knowing nothing of quads, are they a high current demand application?

[Toni Reynaud]

Putting a dead short on a LiPo pack quite possibly will not result in a runaway fire because the thin aluminum looking strips connecting the cells inside the pack will often act as a fuse and rupture in the first few millisecond of a short, thereby preventing an overcurrent situation with a possible resulting fire. Trust me on this one.

[Bob Burton]

Posted by Erfolg on 08/06/2016 16:16:49:

Bob

I had been led to believe that it was not desirable to store Lipos at low temperatures (most fridges being set to about 4 deg C). I guess that you store in the semi discharged/storage voltage. My understanding that if stored when at max capacity it was the temperature drop that could cause the lipo to exceed the max voltage as when charged at ambient. Not being an expert, the views of some informed people would be useful.

Again knowing nothing of quads, are they a high current demand application?

Like many subjects you can find conflicting advice and stories on the Web. Putting my lipos in the fridge is a fairly recent innovation since we got a new 'fridge and the old one was relegated to the garage and now holds beer and lipos. May main concern was that the garage can get quite hot.

Compare and contrast http://www.rcgroups.com/forums/showthread.php?t=2537287 and http://www.rcgroups.com/forums/showthread.php?t=1694131 for two different views, although the circumstances were not quite the same.

As to the current demand in quads being high, then the answer is yes, and no ! There are, after all, 4 motors being used to pull the model into the air and no other form of lift, but what makes most difference is the style of flying. If I just pootle around not doing too much then I can easily get 8 minutes but start throwing them around, at least within my limited ability, and the flight times drop off as more current is used recovering from manoeuvres which uses higher current is short bursts

Summary : I don't know what to do for the best and neither, so it seems, does anyone else.