Graphine / Lipo Batteries in Motion RC's Future?

[OV10]

Here is the story on graphene. We've looked into it extensively. After consulting with universities and having the graphene packs checked in a lab, it has been reported to us that the graphene packs in fact contain no graphene within the cells. We've been told by leading experts in the field that a true graphene cell battery is the future but none exist at this time anywhere in the world. So what are these batteries? What is all the hype and why do they work better? We've been told the connection between the cells is a pure carbon sheet which makes the packs slightly lighter with lower resistance. This is due to the fact that carbon is such a fantastic conductor as compared to metal. The resistance of the cells themselves within the packs are the same as a normal pack. The decrease is due to the conductor between the cells. The only negative is the way the packs discharge (if you can call it a negative). Due to the lower resistance of the conductor connecting the cells, the cells have a much more even discharge which means you will not feel it as your pack is draining. This has caused some to over discharge their packs ruining the cells within the pack. The cells themselves are no different in size, weight, or composition from a regular LiPo battery so you should not notice any capacity difference when comparing new packs. Remember new packs will always have more capacity than used packs since time and use is the enemy of capacity.

Knowing all of that, we are working on our own high performance carbon conductor packs with the same conductor. The goal is to have something in a few months. Additionally, we've switched factories and completely changed the formula for our Admiral and Admiral Pro packs so you are going to see a big performance gain with "regular" Admiral packs and Admiral Pro packs. Those will arrive in a few days.

Hello Tom..........been more than a few months. Has any progress been made?
By the way, the newer formula, slimmer packaging and better performance of the Admiral LiPo 4S 4000 40C and 6S 4500 40C over the prior 4000's for both have been great.

[Martin55]

Graphene is very interesting material and perfect electrical conductor. So its usage in batteries was a sure thing from start. If you are interested in this material then this is a good blog to start. Graphene batteries have certainly some very interesting properties. On the other hand I have also heard that they doesnt hold that well after more recharge cycles.Certainly its still fresh tech so you can expect to see more and more advanced in the near future.

[Zep]

Yes, my charger terminates discharge when the lowest cell gets down to 3.00V, not 3.0V times cell count. Just to be safe I may set cutoff voltage to 3.2V. I made a few discharge curves on older lipos and found not too many milliamp hours left after voltage goes below 3.2V/cell anyway. Thanks for the input.
But I would still like to know if anyone gets more capacity/flight time with Admiral lipos or found them to be otherwise superior to other brands.

[WintrSol]

Well, if you can be sure that no cell in a pack goes below 3.00V during discharge, you can get away with it.. Does your discharge tool monitor all cells, and shut off when the first cell is at 3.00V, even if the other cells in the pack are higher, or does it discharge to a total pack Voltage of 3V times the cell count?

[Zep]

Who told you that? Discharging to 3V/cell at any rate causes ion migration at the surface of the electrodes, which increases internal resistance; cell temperature is not an indication of damage. Each time you do this, you reduce the amount of current you can draw, and increase the temperature of the battery during flight.
Next question: do you go through the discharge as soon as the charge cycle is complete, and, do you use the balance mode of the charger? Just curious, as a 10% capacity over the pack rating is a lot to expect from a temporary surface charge.

No one told me that but look at these links which mention discharge down to 3.0V. Who told you that discharging at 0.33C to 3.0V/cell just a very few times will significantly reduce battery performance?

http://batteryuniversity.com/learn/article/bu_216_summary_table_of_lithium_based_batteries

http://batteryuniversity.com/learn/article/discharge_characteristics_li

Also see attached excerpt from Hitec X4 AC Pro charger manual showing lipo discharge voltage down to 3.0V/cell. My Turnigy charger manual says same thing and in fact is programmed to discharge to 3.0V/cell. Internal resistance of my Admiral 4s/3600mah is still at about 4.5 milliohms/cell after 4 flights as expected for new lipo of that type. I get the ion migration part but let me say again that I perform the 3.0V/cell discharge test very infrequently so as to avoid permanent damage. I did it on this lipo twice only because initial capacity was way over spec and I wanted to verify.

After charging at 1C rate in balance mode I let the battery sit for a few minutes before discharge.
.

[xviper]

I do not fly my lipos down to 3V/cell, only discharge to 3V/cell at very low current on my charger. I do this very infrequently to check health of my lipos. Discharging down to 3V/cell at low current will not damage lipos, they don't even get warm. As I said when I want to measure capacity I use the charger discharge mode which discharges to 3.0V/cell at low current. Discharge power is limited in the charger to 20 watts therefore current is roughly 1.2 amps for a 4s.. I have found that measuring what goes back in gives inconsistent estimate of lipo true capacity. You need good estimate of how much you took out before measurement of what you put back in has any meaning.

I have never heard of this practice with LiPos but hey, if that's what you believe, who are we to tell you otherwise. For me at least, this is not a way to determine battery health. Not getting warm doesn't mean anything. I've discharged batteries down to zero using a light bulb (before disposal). They don't get warm then either.

[WintrSol]

Discharging down to 3V/cell at low current will not damage lipos, they don't even get warm.

Who told you that? Discharging to 3V/cell at any rate causes ion migration at the surface of the electrodes, which increases internal resistance; cell temperature is not an indication of damage. Each time you do this, you reduce the amount of current you can draw, and increase the temperature of the battery during flight.
Next question: do you go through the discharge as soon as the charge cycle is complete, and, do you use the balance mode of the charger? Just curious, as a 10% capacity over the pack rating is a lot to expect from a temporary surface charge.

[Zep]

I do not fly my lipos down to 3V/cell, only discharge to 3V/cell at very low current on my charger. I do this very infrequently to check health of my lipos. Discharging down to 3V/cell at low current will not damage lipos, they don't even get warm. As I said when I want to measure capacity I use the charger discharge mode which discharges to 3.0V/cell at low current. Discharge power is limited in the charger to 20 watts therefore current is roughly 1.2 amps for a 4s.. I have found that measuring what goes back in gives inconsistent estimate of lipo true capacity. You need good estimate of how much you took out before measurement of what you put back in has any meaning.

[xviper]

3V/cell is a bit on the low side for me and I consider such batteries to be nearly "dead", which is a bad thing for LiPos. When I've "overflown" a battery down to that, I fear I've nearly destroyed it and whatever lifespan is left is greatly diminished. Why do you feel the need to discharge them down to 3V/cell after use? I've not heard of measuring what comes out. Most people measure what goes back in and rarely allow voltage to go much below the recommended storage voltage of ~3.75 - 3.8V.

[Zep]

WintrSol. I am measuring capacity on Turnigy Reaktor charger. I fly from full charge down to >25% capacity remaining then after cooling charge to 4.2V/cell at 1C rate. I ignore capacity restored to battery. Then I use charger discharge mode at 20 watt limit down to 3.0V/cell at which point the charger terminates and displays capacity removed. Capacity displayed is about 4200mah after 4 flights. When I measure capacity of new Electrifly,Turnigy Nanotech, blue and Zippy lipos in this manner I get much closer to their advertised capacity. After many flights, some abusive, these lipos show significantly reduced capacity as expected so it will be interesting to see how the Admiral holds up.
Zep

[WintrSol]

@Zep: How are you measuring capacity? First, you should never discharge to low Voltage cutoff (LVC), second, if you want your battery to last, you should not discharge to lower than about 3.7-3.8V per cell (14.8V total), after resting a few minutes after use (~15-20% charge remaining). That means your charger should show no more than about 3000mAh returned to the battery during charging.

[Zep]

What's the dang deal? I have 4 flights on my new Admiral 4s 3600mah and capacity is still 4200mah compared to other brands which typically measure quite close to spec capacity. Am I just lucky with this one lipo or are these things really better?

[OV10]

Hi...i am a new user here. As per my knowledge under fairly high discharge levels in EDF jets, they come back down barely warm to the touch, no swelling, holds cell matching well, cells balance charge nicely, IR maintains low reading under the same conditions, seem to have a more durable packaging and plates, and holds voltage well under load. I have no idea on longevity yet because they are still somewhat new to me, so I need many more flights on each pack to see whether they hold true to their advertised longevity specs. This is coming from someone who's not a biased LiPo brand individual too. If I try something and it works out, great, I'll keep using it until it doesn't. I have only tried Turnigy Graphene batteries though in two different sizes for different applications, a 4S 1300mah 65C, and 6S 5000mah 65C. One thing I hope that doesn't occur is LiPo brands advertising their non Graphene related LiPo's as Graphene related LiPo's.

Hello LulaNord and welcome to the Squawk,
Your hope is most understandably felt by many but as it stands there is no true graphene battery developed yet. Here's a good starting reference in case you didn't read all of this thread.
https://www.hobbysquawk.com/forum/el...4485#post64485

[LulaNord]

Hi...i am a new user here. As per my knowledge under fairly high discharge levels in EDF jets, they come back down barely warm to the touch, no swelling, holds cell matching well, cells balance charge nicely, IR maintains low reading under the same conditions, seem to have a more durable packaging and plates, and holds voltage well under load. I have no idea on longevity yet because they are still somewhat new to me, so I need many more flights on each pack to see whether they hold true to their advertised longevity specs. This is coming from someone who's not a biased LiPo brand individual too. If I try something and it works out, great, I'll keep using it until it doesn't. I have only tried Turnigy Graphene batteries though in two different sizes for different applications, a 4S 1300mah 65C, and 6S 5000mah 65C. One thing I hope that doesn't occur is LiPo brands advertising their non Graphene related LiPo's as Graphene related LiPo's.

assembly circuit

[TOO TALL]

motion if you started carrying graphine batteries I would buy them, I have a few and like them very well. I prefer them over the admirals.

[Tom]

6S 4000 are nearly identical. I think the new ones are a couple mm longer and a few mm less thick with the same width

[F106DeltaDart]

Have any of the dimensions on the Admiral Pro 6S 4000s changed? It was one of the only batteries that fit perfectly in my 500 heli. Otherwise, good news about the performance increase! Might have to look at a few battery purchases soon.

[PappaBear]

Thats very interesting information Tom. I am aware that carbon is a terrific conductor of electricity. They have been using carbon in the spark plug leads of car engines for many years. However Graphene is not a new material but it does have immense strength properties and its very light.

Martin.

[Tom]

Thanks Twowingtj. BTW, we just doubled checked the weight of 5 different 4S 4000 packs. Most were at 388g and we had one at 394g. We weighed them on our calibrated shipping scales we use for small packages.

[bradl4648]

I just bought the 4's 5000 60 c and yes they are an 1 longer then the original but thin by a half an inch. My weather sucks here so hope to try them soon. using them in parallel for 8's for my tomcat 110 motor its going in my hanger 9 lancair legacy should be a great fit.