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Jan 29, 2016, 07:42 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
What about specific capacity, specific energy, same as non-graphene LiPo?

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Jan 29, 2016, 08:10 AM
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Race Miata's Avatar
As has been mentioned by nighthawk, the 4S 1300 pack comes in at 175g. By my first estimate when I received mine and weighed them I knew these packs weren't going for the highest energy density. For that among high power lipos the Bolt (Li-HV) still has an edge.

Graphene 4S 65C 1300 = 175g. Energy density = 4 x 1.3 x 3.7 / 175 = 110Whr/kg

Bolt 3S 65C 2400 = 202g. Energy density = 3 x 2.4 x 3.8 / 202 = 135Whr/kg

Of course other lipos that are not designed for high power discharge will be able to achieve higher energy density.
Jan 29, 2016, 08:15 AM
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Race Miata's Avatar
Quote:
Originally Posted by Julez
Added:
https://www.rcgroups.com/forums/show...&postcount=419

But I have to say it is nice to see a technology with the actual chance to be in the hands of ordinary people.
I love how HobbyKing send these out for ordinary people to test them before these are ready to be sold for the public. Will be interested to see if someone comes out to say HobbyKing steals their stuff.
Jan 29, 2016, 10:15 AM
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scottc39's Avatar
Here is my in put on these packs as well, I was given a few of the 4 cell 1300 65c batteries to use so there was others getting a first chance to try them, do read all the way down on my input so it is understood that I could only put them to use by using them, they are a great battery with the 65c rating and worked and held great power while running in my model Truggys.

I did get a chance to use the batteries you sent in my RC truck, 1 being a ACME Dominator truggy 1/8 scale and the other a Ofna 1/8 scale truggy. what I did was get a parallel harness to get a higher mah, now rc cars can pull a lot more amps then say planes do so the 65c rating was really a good thing, with a low mah I would get around 4 mns of running around my yard in the snow, the esc would not even go into LVC with these batteries and that was nice to, the batteries gave tons of power all the way to the end of any charge left in the packs, a few times I checked the battery there was only 10% of capacity left in them. My level of reviewing is by using these batteries
Jan 29, 2016, 10:31 AM
Registered User
hello,

I thought that Graphene will enable to have more energy density? may be the "graphene" word is just for marketing?
Anyway, if the batteries are getting better in lifetime, this is not bad..
Very hard to believe because Graphene is so thin that it is very difficult to interface something with it ...
Jan 29, 2016, 11:50 AM
BrainFart RC-Pilot
TreeDiver's Avatar
Rick, cool test! Looks like a very interesting new development!
Jan 29, 2016, 01:45 PM
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Race Miata's Avatar
Quote:
Originally Posted by brushman
hello,

I thought that Graphene will enable to have more energy density? may be the "graphene" word is just for marketing?
It's always trade-off between energy density vs power density. I bet if they could make 25C Graphene it'd have much higher energy density. If I were looking for high energy density batteries I would be looking at lower C rated batteries.
Jan 29, 2016, 03:04 PM
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Never really read about graphene so I followed that link in the OP and followed a few more links. Incredible material, didn't realize it was discovered so recently (2004). Should be an excellent material as a base for new battery tech. With all the wolf-cries of the next great battery, it's good to see something materialize.

A battery that can truly handle 65C and run 1000 cycles without gaining any IR or without losing more than 20% of its capacity is something indeed. Most of these high "C rated" batteries seem to be an exaggeration. In reality I've found they can only put out about half what's printed on the label after they get a few cycles on them.
Jan 29, 2016, 03:39 PM
Frankenstein recycled packs
rampman's Avatar
Thread OP
Actually, the label states 65C but in reality was 30C constant and has been holding around 27C at >900 cycles. The bulk of my discharges were at 24C. She may do 65C bursts but I won't. Well, maybe I did last Saturday when my Tundra with a 5.7L motor did not start due to a dead battery. One of these cranked it up just fine. It was sitting around 3.75 volts per cell and was a bit warm to the touch after a 3 second crank. *eek*

I think the way this Graphene can be applied, and I can verify this in post #2 (reserved) when I scrap a cell is the thin +/- plates' carrier, instead of copper, I suspect I will find a thin layer of Graphene.

I have taken some newer generation cells apart and found what appeared to be a copper metal deposition on plastic instead of a copper plate. Think of how a thin potato chip bag looks but copper instead of shinny metal. It was so thin that I could not really scrape the copper off in a sheet. It seemed to flake off instead. There was very, very little copper in there.
My guess is these will not have any copper. Well, maybe some at the tab area for a good connection to the outer world (tabs). As tough as this is supposed to be perhaps a good crimp will make the connections? I did notice the tab area was the warmest part of the whole pack with my IR thermometer.

I do have a pack taken apart now, that would be a good test on a single cell tonight.

Rick
Jan 29, 2016, 03:58 PM
Registered User
This sounds like it could be great for micro and nano stuff. My Nano QX FPV quad really pushes the little 1S cells to the limit.
Jan 29, 2016, 04:04 PM
Registered User
Interesting. Do you have comparable data (IR and capacity after 900 cycles) for a "normal" high discharge rate lipo?

My guess is that theses "graphene" lipos use a modified anode material. As most of you probably know, the anode in lipo batteries is a graphite-like arrangement of carbon which accepts intercalated Li ions in between the layers. One possibility is that they are using a more ordered graphite anode (larger crystal grains); this could decrease the rate of damage to the anode material during use.

But calling it graphene in this case is not quite accurate. Graphite is made of many layers of graphene. I doubt they are using single isolated layers of graphene for the anode because there wouldn't be enough volume to hold all the Li ions. So it is probably just a bit of marketing calling it graphene, but if the battery performs better, good for them.
Jan 29, 2016, 04:39 PM
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Race Miata's Avatar
Quote:
Originally Posted by ebltn
I doubt they are using single isolated layers of graphene for the anode because there wouldn't be enough volume to hold all the Li ions. So it is probably just a bit of marketing calling it graphene, but if the battery performs better, good for them.
Maybe. Just like the nanotech lipos, I don't care much if they aren't really using any nanotechnology. The fact is my experience with nanotech lipos especially 25C ones are they outperform other 25C or higher lipos and also outlast them when spec'ed properly for the applications.
Jan 29, 2016, 04:57 PM
Closed Account
Yes they typically use a carbon compound film on a foil plate. I imagine they did some work on that film to make it function better. I can never remember how the chemistry works with Li-Ion cells, but I do recall that's where the bulk of wear occurs and where much of the IR comes from. I imagine they're using "graphene" as more of marketing catch word. I don't see how they would be able to replace that carbon film with single layer of graphene, but I don't know maybe that's what they did. My guess is it's probably stacked in some way to perform better than the stuff used traditionally.
Jan 29, 2016, 05:13 PM
Closed Account
Quote:
Originally Posted by rampman
I do have a pack taken apart now, that would be a good test on a single cell tonight.
Would be really informative to see how the cells are constructed. Maybe even torch one to see if it's more or less flammable than a standard LiPo. Could be an improvement in safety as well.
Jan 29, 2016, 05:26 PM
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Race Miata's Avatar
Quote:
Originally Posted by James_S
This sounds like it could be great for micro and nano stuff. My Nano QX FPV quad really pushes the little 1S cells to the limit.
I suggest going the opposite way with batteries for the nano QX FPV. The problem with that quad is that the motors aren't very powerful to carry the FPV equipment and heavy battery so Blade includes small 150mAh. Because of the small capacity, discharge time to 80% SoC is short (3mins) which means high C rated battery which in turn increases weight. I have good luck running HobbyKing Zippy 20C 240mAh bare cell. They are only 0.5g heavier than stock 35C 150mAh battery but since I get 4min flight time out of the Zippy, 20C is working OK so far (I normally spec 25C battery for 4min flight and 20C battery for 5min+ flight).


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