[Baz]

Whats people experience with how to treat new batteries?
I know to charge at less than 1c for a few charges but how much less and how many should I do, should I increase each charge and build up to 1c?
What about discharge, should that be gentle and build up to a faster discharge or go hard as I want max performance from these turnigy blue 2200 3s.

[disoriented]

Hi Barry,

The internal resistance (IR) of a lipo cell goes down during the first few charge/discharge cycles (and never again after that). The biggest drop will typically be during the very first discharge, with only half as much reduction on the next, and half as much again on the third cycle...

In practice, the cell is as good as it's ever going to get by the fourth or fifth cycle. Until then, it's best to take it easy in the air - avoid high current maneuvers - because high IR means the cell is generating more heat.

The purpose of moderate charge rates during the first few cycles is to observe how easily the cells balance. If there is lots of drift, as in two out of the three cells get to 4.20V nice and quick but the third lingers at 4.15V to 4.19V for quite a while, that third cell is suspect. If the behavior doesn't go away by the fifth cycle, it likely never will, and chances are that pack will always be a bit wonky.

1C charging and relatively gentle (low current) flying for the first ~5 cycles is all it takes. After that, the pack is as ready as it will ever be.

An IR meter is probably the single best tool for gauging lipo health. It has to be precise, or the readings are pointless. Some of the better quality chargers (Powerlabs & the iCharger line) have inbuilt IR measurement circuitry, and ProgressiveRC over in the US sells a dedicated precision IR measurement device (HK does a clone, but by all accounts it's not worth the thirty bucks).

My Turnigy blue 2200 3S packs have served very well. Out of a dozen, a couple are approaching 330 cycles, and they're still fine even for 4min tear-the-heli-apart-in-midair flights

[greggold]

My experience is mostly with Turnigy lipos 2S and 3S. I always charge at 1C and I have not had the problem described by disoriented of a lipo that is hard to balance. I dont find a need for recharging at 2C or 3C, although I can understand some flyers who recharge at the field might want to do that.

Turnigy now is a dominant player with a range of lipos for each category, 2S, 3S and 4S. To achieve this market position requires good products and a vast amount of testing of lipos, including how many cycles before a pack becomes unusable, and the effect on performance of various recharging regimes, including <1C charging for the first 5 recharges, the effect of 3C recharges etc. If any regime is superior I do not understand why testing data held by Turnigy is not used to issue customers with evidence-based guidelines for recharging. I think the experience of any one flyer might only reflect luck and chance, and people are generally confused or uncertain about the best way to recharge - I certainly am. If the recharging regime makes no difference, users need to know this.

My impression from reading rcgroups on lipos is that avoiding drops in cell charge below 3.7v may keep lipos in better shape. When the aircraft noticeably loses power in the air I find on testing cell voltages on landing that one cell may have fallen to 3.3v or less. To avoid this I am trying the FrSky SP-FLVS - Smart Port Lipo Voltage Sensor which is sold by Aloft Hobbies. I am setting it up on my phantom so I get an audible warning when the cell with the lowest voltage reaches 3.7v.
A typical review of this sensor:
"Much better solution to battery monitoring than an on-board buzzer. With this sensor you have complete voltage level telemetry and can setup multiple audible reporting and alarms from your Taranis for any voltage trigger point(s) and/or battery cell combos you choose."

A second measure is to charge lipos in storage mode after a flying session, immediately on arriving home - this balances all cells and raises the voltage to 3.9v, which means its quicker to balance charge the lipos prior to the next flying session.
I feel the above 2 steps make sense to maintain battery condition, however like breaking in lipos it will remain guesswork until lipo manufacturers release their data on largescale testing over lipo lifetimes, and provide evidence based recharge guidelines. I fear the reason they dont is that they think its better if consumers are kept in the dark; if true this is a sad and stupid policy.

[BOB]

Hi guys. Now I don what is sound ignorant on this subject but how do you charge a battery at 1C? I normally just set up the normal charge rate on my HK charger the way I was told when I first joined the club? I’ve got some new batteries that I haven’t charged yet so need some advice?.

[Baz]

Hi Bob

If your battery is 1500mah, thats 1.5 Amps and charging that battery at 1.5A is 1c.
If you charged it at 3A that would be 2c, 4.5A =3c etc.
2200mah would be 2.2Amps, 3000mah would be 3Amps, this is the standard charging rate, 1c.
Only batteries that say they can be recharged above 1c should be.
With my new 2200mah batteries I will charge at 1.7A for the first charge then 1.8 then 1.9,2,2.1 and then 2.2 and always a balanced charge.
Of course you don't have to do this,except 1c limit, but I'm looking for max output and max life, like those heli tear it apart nutters
When asking 100% from your battery there are huge differences between them and they need to be looked after and respected.
Hope that helps, see you at the field.

[BOB]

HI, Barry and Andre. The question, someone told me quite a while ago that you can discharge batteries using a light bulb plus low voltage alarm?.

Also Barry sorry I haven’t been down the field suffering a bad bout of flu it’s a real bummer.

[disoriented]

HI, Barry and Andre. The question, someone told me quite a while ago that you can discharge batteries using a light bulb plus low voltage alarm?

Hi Bob,

We could spend hours talking about that topic. This might become a long post

For starters, let's define two useful equations:

1) V = I x R, voltage equals current times resistance, known as "Ohm's Law"
2) P = I x V, power equals current times voltage, sometimes called the "Power Law"

Most classic incandescent bulbs are a simple coil of wire. The house variety are rated for 240 volts, at say 60 watts of power. Plug those numbers into the second equation, and it's easy to calculate the current flowing through a 60W bulb:

P = I x V, 60 = I X 240, 60 / 240 = I

In other words, current through a household 60W bulb is 60/240 or 0.25 amps. In turn, we can use that result in the first equation to find the resistance of the bulb's filament:

V = I x R, 240 = 0.25 x R, 240 / 0.25 = R

The filament resistance of a 240V 60W bulb is 240/0.25 or 960 ohms.

Assume for a moment that the resistance is a constant at all voltages and temperatures (in reality it's not), and imagine that a 3S 2200mAh lipo (12.6V when fully charged) is connected straight to a 240V 60W household lightbulb. We can calculate the current by using Ohm's Law:

V = I x R, 12.6 = I x 960, 12.6 / 960 = I

Current flowing through that bulb would be a measly 12.6/960 or 0.0131 amps, and that probably wouldn't be enough to make it light up at all. At that rate, the lipo would take about a month to discharge, so clearly household bulbs aren't the thing for discharging lipos!

A more suitable alternative is in the next post...

---

The same two equations ALWAYS hold. Let's now use a 12V 21W car bulb, of the sort that cars used to have in their tail and indicator lamps (before this new LED fandanglery). Assuming the same full 3S 2200mAh lipo:

P = I x V, 21 = I x 12.6, 21 / 12.6 = I

Current through the 12V 21W automotive bulb is 21/12.6 or 1.66 amps. We can calculate the filament resistance by plugging those numbers into Ohm's Law:

12.6 = 1.66 x R, 12.6 / 1.66 = R

Filament resistance of a 12V 21W automotive bulb is 12.6/1.66, or rather 7.6 ohms.

Discharging a 3S 2200mAh lipo at 1.66A is pretty much exactly what an average hobby-grade lipo charger will do, except it has to dissipate that ~20 watt power into the air as heat, with its tiny 40mm fan whirring itself to bits in the process.

Rigging up two of the 12V 21W bulbs in parallel would double the current, thereby halving the time-to-discharge. Four bulbs in parallel quadruples the discharge current, and now we're discharging at 80W - which is a discharge rate of [(1.66 x 4)/2.2=] 3C, which means around 20 minutes to totally empty, or about 15 minutes of gentle flying with an Easystar.

The trouble with automotive bulbs is that they themselves don't have voltage sensing or a low voltage cutoff (LVC). That quad-bank of 12V 21W bulbs in parallel will happily run the lipo all the way down to 0%, if left alone to do it.

A lipo low-voltage detector can deal with that issue, kind of. If hooked up across the lipo's main wires, it will beep/scream when the voltage reaches a predetermined level. Trouble is, most are designed to sound the alarm at say 3.0V/cell or thereabouts, which means they won't be much use if attempting to discharge from full to storage voltage (3.85 V/cell) under load.

The other problem is that you cannot discharge 6S batteries with the same setup, because at 25.2V (full) they far exceed the voltage rating of a 12V automotive bulb. That problem can be rectified by hooking up the four bulbs in a 2-by-2 configuration, two parallel lines of two bulbs in series, but when it's all said and done that's all a lot of fiddling when you could instead...

---

... buy one of these for $28

http://www.ebay.com.au/itm/AOK-3in1-Batt...OSw5VFWJK5~

That thing will discharge at up to 150W, far more safely and accurately than the bulb method.

For 28 bucks there's really no point fiddling with bulbs and bulb sockets, and wiring, and lipo voltage detectors, and having to listen out for the alarm... The automated 150W lipo discharger is a simpler and better solution. <-- That's the short summary of the entire post.

[disoriented]

AU$24 on Banggood, with free shipping

http://www.banggood.com/AOK-3-in-1-150W-...51214.html

[Spook]

I have an old 64mm EDF and ESC on my bench with a multi watt measure for discharging any batteries. This normally takes around 5 minute's to get to storage charge and then I plug them in for balancing. I use the EDF as they draw the most current and there isn't a swinging prop to chop up the air (and your hand) so much in the garage. The control is done via a servo tester and generally 1/2 throttle for the 5 minutes.

[dfw]

Adding this note to the battery Ramblings,

Just got some fresh LIPO' s in the mail.
Noted that, In line with the latest IATA rules for airfreight of Lithium Batteries, HobbyKing now ships batteries out at a 30% state of charge. meaning your freshly received batteries are NO LONGER at storage charge level when you receive them, and you should charge them to storage level asap.

Anybody has any view on the Graphene batteries series ? I ordered Graphene as they were just a 1$ more, and they do get good reviews online. They come in a fancy box + (flamable !?) carry bag. Seems the extra $ sits in the packaging rather than the battery.

Dirk.

[BOB]

HI, dirk. I also received some batteries from HK this morning only have been waiting about three months, or so thanks for the warning I’ll have to get charging straight away.

[disoriented]

Although 3.85V/cell is the generally accepted storage voltage, there is nothing particularly special about that number except the fact that it is in the middle of the zone which is considered safe - from 3.70V/cell to 4.00V/cell.

Packs shipped at 30% charge will be at say 3.75V/cell. That is a perfectly safe state, even for longer-term storage. In an absolute sense it is safer than 3.85 because there is less energy in the pack to stoke a fire if something "bad" happens. (No doubt that's why they switched to shipping in a 30% state of charge.)

There's absolutely no pressing need to charge 'em up to 3.85V/cell.

[dfw]

I agree, however HK does put a label on the batteries urging you to recharge to storage level asap. I guess it also has to do with shelf life, since they now store the batteries at a lower charge, they will reach discharged state faster, So pending on the time the battery spend on the shelf, the chance is higher you receive the battery well below the stated 30%.

[greggold]

I have been using a 3000mah 3S 15C graphene battery for about a month. I have not noticed anything different from similar non-graphene packs. I did not particularly want a graphene pack, there are not many packs in 3000mah size with a X60 power plug which led me to this particular pack. As a sport flyer, I have not been able to test whether graphene packs are better.

I had a quick look on rcgroups to see if the following is available:
-a test comparing power in graphene/non-graphene packs of similar size/capacity
-a test whether any desirable characteristic - more recharges per lifetime of the pack, or more crash resistance, or longer flight duration, or faster charging, or less fire risk etc are superior in a graphene pack.

I did not find any objective tests or evidence. I am inclined to think the only advantage of graphene accrues to Turnigy who charge more for a graphene pack. However I am keeping an open mind and hope some evidence comes available soon.

Adding this note to the battery Ramblings,

Just got some fresh LIPO' s in the mail.
Noted that, In line with the latest IATA rules for airfreight of Lithium Batteries, HobbyKing now ships batteries out at a 30% state of charge. meaning your freshly received batteries are NO LONGER at storage charge level when you receive them, and you should charge them to storage level asap.

Anybody has any view on the Graphene batteries series ? I ordered Graphene as they were just a 1$ more, and they do get good reviews online. They come in a fancy box + (flamable !?) carry bag. Seems the extra $ sits in the packaging rather than the battery.

Dirk.

[Baz]

The guy who helped me get into quads has had 1500 4s 65c Graphenes since they came out, about January.
He's very happy, still flogging them and they are going strong.
I think Turnigy do good batteries for the money, nanotechs, blues and Graphene.
Just got to be always over supplied with power than under.

[BOB]

RE: quality of battery testers???.
Hi guys. This morning I charged some batteries as my normal practice I tested them after charging with a cheap brand-new battery tester that I have bought from eBay I immediately notice a problem they were giving fairly low readings I then retested using my old and venerable HK010 tester and then got a normal results below is typical of the reading of the five batteries I tested.
eBay tester.
4.18/4.18/4.21
HK010
4.19/4.22/4.21

[dfw]

RE: quality of battery testers???.
Hi guys. This morning I charged some batteries as my normal practice I tested them after charging with a cheap brand-new battery tester that I have bought from eBay I immediately notice a problem they were giving fairly low readings I then retested using my old and venerable HK010 tester and then got a normal results below is typical of the reading of the five batteries I tested.
eBay tester.
4.18/4.18/4.21
HK010
4.19/4.22/4.21

Hi Bob,

I would say both testers are giving a similar result.
a delta of 40 mV (0.04V) is not that much. some margin error is to be expected.
Is the middle voltage consistently giving a +40mV higher reading for all 5 packs tested ?

[GaryP]

Oh, I'm thinking that the behavior doesn't go away by the fifth cycle.
I am setting it up on my phantom so I get an audible warning when the cell with the lowest voltage reaches 3.7v.

[disoriented]

I am setting it up on my phantom so I get an audible warning when the cell with the lowest voltage reaches 3.7v.

Voltage sags under load, and thus in-flight voltage readouts are rather unreliable. You may find that the voltage of that same cell which registered 3.7V during the flight climbs back up to 3.9V or more after you land.

[BOB]

Yes that’s exactly what happens to my V3 black Mamba quad the red light comes on indicating landing and when I land and shutdown the red light goes out.

[disoriented]

One better option is telemetry based on current over time. FrSky has several telemetry gizmos which can feed current info back to a Taranis (or Horus!), thus enabling a warning to fire when the pack is down to say 30% full.

Some fancy ESCs can do cutoff based on capacity, rather than voltage. For example, the ESC can be configured to pulse the motor after it observes 2000mAh being drawn from the battery. (True, it would be a pain to reconfigure every time you flew with a bigger or snaller pack.)

[Baz]

Voltage sags under load, and thus in-flight voltage readouts are rather unreliable. You may find that the voltage of that same cell which registered 3.7V during the flight climbs back up to 3.9V or more after you land.
[/quote]

Is that not the point of in flight readings as that battery is low on 1 or more cells and is all the power available to you at that time. It is also a vulnerable time for the battery as drawing large current now can damage the cell. Good alarms are easy, cheap and tell you whats happening in real time, unlike transmitter timers.
I run 2 alarms, 1 is at a safe voltage(3.6 or 3.7) which is when I stop high current draws and idle. The battery will recover and the alarm will stop. I continue to idle/practice low current flight and when the alarm starts again I land. The second alarm is a 3 in 1 with voltage and lost plane selected. This is measuring the main voltage and set to just above the point of no return. Obviously 2 alarms is land NOW.
https://hobbyking.com/en_us/turnigy-3-in...alarm.html

You soon learn all batteries are different in their behaviour, discharge, recovery and how flight times can vary depending on adrenalin off the thumbs.

Each planes electrics will shutoff at different voltages so start at 3.7V to be safe.

[disoriented]

Is that not the point of in flight readings as that battery is low on 1 or more cells and is all the power available to you at that time. It is also a vulnerable time for the battery as drawing large current now can damage the cell.

There are two fundamentally conflicting requirements:

1) A discharge curve which is as flat as possible. Ideally, a LiPo cell would stay at 4.20V until it was say 80% exhausted, at which point its voltage would rapidly fall off a cliff to 3.7V. That ideal is still unachievable, but the more technology advances the flatter the discharge curve becomes.

2) The ability to sense remaining capacity based on cell voltage. This is effectively impossible with the idealized stays-at-4.20V LiPo, and it's getting ever harder even with real life battery packs. They all tend to exhibit the fall-off-a-cliff discharge behavior, to one extent or another, unlike traditional NiCd and NiMh chemistries.

The more rapid the discharge, the worse the problem. An EasyStar puttering along at 25W motor power may be able to say aloft for 20 minutes or more, and voltage sensing is a relatively accurate way to deduce how much is left in the pack. On the other hand an EDF or high-powered heli setup which exhausts the battery in 3 minutes is not a good candidate for voltage-based alarms. Mere seconds separate the point where the cell hits 3.7V under load, and the point where the thing falls out of the sky or damages the LiPo through overdischarge.

Wish we had a decent weather weekend so we could all go fly instead of talking about it

[helijeli]

Just thinking the same thing Andre (decent weather), hasn't been that much rain but seems to be windy all the time. Haven't had a decent day at the field in ages. Popped down last weekend but 2 flights in, too windy again.
I agree with your battery thoughts. I've got a few low voltage detectors (attaches to balance plug to monitor each cell), but rarely use them as haven't decided best way to use them. I thought just set it to alarm at 3.7 or 3.8V for 40% capacity left but that's with no load. As you mentioned, capacity left as a function of Voltage, varies with load and battery condition. You really need to set it lower - maybe 3.3 or 3.4V, and make a judgement when it alarms under load. See what you have left after you land to see if you gauged it right, and it will be different with different (condition) batteries.
Hope to see down the field sometime (good calm weather!)

[BOB]

Hi guys. I came across a website HeliPal webpage below, who are selling batteries for quads but I notice there fairly expensive compared to say HobbyKing but then when I did a bit of investigation I found that their batteries are a lot lighter than HK is and will no with quads weights important?.

http://www.helipal.com/index_tag.php?tag...,Batteries&tags_type=Parts,Accessories,Features

[Busboy]

Hey guys, after being down at the field today and seeing a fantastic turnout and so many different aircraft flying and some not making such a graceful return to terrafirma. Upon checking a pilots battery pack, it was found the the voltage difference between cells of a flight battery was a difference of around 72% which caused the battery to lose the power to fly the aircraft.
Whilst chatting to Marco, I noticed that he had connected a circuit board up to the balance lea of one of his batteries, I inquired about this and he told me that the board actually balances the cells of the battery better than any charger. He showed me a battery which had a cell voltage differential of about 76%, he asked me over to the flight area while he flew his F-18 jet and some more chatting, it was about 15 or so minutes had past and we went back to that battery and the differential was now up to 82%. He swears by using this balancer especially while charging to get a safer flight and keep the batteries in good condition and longer life.

The reason I'm posting this is to see if anyone else is interested in purchasing 1 or more of these like myself, I would make a bulk purchase for everyone wanting 1 or more. The price per balancer is US$32.04

[BOB]

Hi, Todd. I have HK010 battery tester that has the same function but shows you a digital display and it can take a while to balance up the battery also has an alarm, also with most battery chargers even when using their balance setting don’t always balance completely.

[dfw]

Any battery with a 70 % imbalance I would treat with extra care.
If the imbalance comes from over-discharge, then a very slow charge might fix it.
(A charger typically will re-balance by shorting a resistance over the higher V cells, allowing the lower cells to catch up. this is a slow process, a balancer like this one might speed this up)

However, if after re-balancing the battery persists in getting badly imbalanced after discharge, I 'd say the battery is ready for retirement. with one cell not holding charge, it won't deliver anywhere near the expected power, and you have the risk of the bad cell going ugly (explode or fire) during charge or discharge cycles.

[disoriented]

Any battery with a 70 % imbalance I would treat with extra care.
If the imbalance comes from over-discharge, then a very slow charge might fix it.
(A charger typically will re-balance by shorting a resistance over the higher V cells, allowing the lower cells to catch up. this is a slow process, a balancer like this one might speed this up)

However, if after re-balancing the battery persists in getting badly imbalanced after discharge, I 'd say the battery is ready for retirement. with one cell not holding charge, it won't deliver anywhere near the expected power, and you have the risk of the bad cell going ugly (explode or fire) during charge or discharge cycles.

Agreed. A pack which is repeatedly unbalanced to that extent is not long for this world, and when (potential) crash costs and time are factored in, the cheapest thing to do is to replace the pack.