Getting to 100km, with a big help from GEB 8043125.

Today we decided to finally get out of the office and go fly !
I wanted to test a new pack which has been sitting on my desk for a while, a 14.8V 4s4p 24400mAh. 

This is a different type of lipo , with a energy density of 262 Wh/kg. 

Simply, this battery has an energy density which is x 1.62 of regular lipo (160 Wh/kg), which can help you get long flight time.  This GEB even beats the  VERY expensive Maxamps battery, which is 180 Wh/kg.  Ok, so the Maxamps can handle a few more C's. But if you are going for long flight time, then the GEB is for you !

The downside of this different battery chemistry is that the discharge rate is only 1C/2C maximum. You must take this into account when planning to use this battery. For example: a 3s1p 6100 battery should not be discharged at higher than 12.2A. A 4s4p 24400mAh battery should not be discharged at higher than 48.8A. A three second burst at 3C is supposed to be OK. If you discharge any lipo above its maximum discharge rate, it will instantly become damage and will never deliver the same performance as new.

So, with that in mind.. 

I grabbed a 680Pro by Tarot which I had laying around and threw on a Pixhawk on it. A quick auto tune and I was flying, albeit not very well- sorry Pixhawk you need more tuning. 

 

Since I only have 6S capable  speed controllers ,there was no possibility to go up to 8S. That will be by next test flight. 

 

The current needed to hover was about 30A, this is safe the battery pack I was using.

Pack was hot after the flight , but under 60 * C for sure. 

 

My plan is now to do a couple of more flights like this. I need to know if the battery will keep its capacity (performance) over multiple discharge cycles at 1.25C (30A).  I am concerned about the voltage sag which was at about 15% of capacity.  Battery getting hot is never good, either. 

Btw, loiter worked at the office, but drifted at the beach. I didn't debug it, but I guess I should just look at the logs. Flew in STABILIZE.

 

This flying day got me fired up to build a wing for the elusive 100km badge.. Actually, I think a 100 km flight with be piece of cake with a fixed wing.

If I can make  RVJET cruise at 50W @ 60km/h.... well, lets just say I might be going fishing to Bimini (200 km trip)

I will start with 14x5.5 CF multi rotor  prop and 380 kV , 22.2V .  We will need more pitch, but 5.5 is all I have atm. 

3s2p 6100 22.2V shown.  I will put more batteries , no worries. :)

SunnySky 3508 - 380kV

 

Here comes the plug, you can buy these batteries at RangeVideo. I know a lot of UAV guys have been looking for them.
If you need something with higher discharge rate (30C), I suggest to check the new 16Ah cells from Gens Ace.
they are 180Wh/kg plus the batteries themselves are very nicely assembled; aluminum radiator sheet over top and bottom, plenty of foam on the ends to protect the cells, overall I was impressed. You can use  single 6s 16000mAh pack on an S800. Probably 13-14 minute flight times with and NEX5 Zenmuse.
1. RV Power = Gens Ace cells
2. RV Endurance = GEB cells

 

Lastly, the video from this morning.

https://www.youtube.com/watch?v=BDP6EHtCAuQ

Views: 14220

Comment by Thijs Sillen on March 24, 2014 at 8:08am

I also contacted Panasonic / Sanyo and under no circumstances do they cell bare "Panasonic" ion/ lipo cells.

Not to businesses or the general public. When i directed them to several shops in the eu that sell the bare cell they said:

Dear Mr. XXXX,

Yes, but this is not our business and not a business with SANYOComponent Europe GmbH.

Sorry, but It is not possible to buy Li-Ion single cells from us.

When you buy the "de-soldered" 18650 Panasonic cells from china (Taobao) they cost around 5 usd each.

It seems that it is not possible to get them from panasonic directly.

The yet to come out Panasonic NCR18650C 4.35V 4120 mah has an energy density of around 285 wh/kg and will last for hundreds of cycles. But they aren't really available (at least for the general public).

Comment by Daniel Allen on March 24, 2014 at 8:33am

NCR18650C 4.35V 4120 mah!?! Wow I want that, I hope it comes out soon. That will easily be the next record breaking cells. If only they made flat cells.

Comment by Tommy Larsen on March 24, 2014 at 8:50am

I imported this list into Excel, made a formula to divide mah/grams for every battery and found that the one at number 320 has the best ratio :)

http://www.gebattery.com.cn/product/polymer-li-ion-battery.html

Comment by vova reznik on March 24, 2014 at 10:52am

"I will test to see what happens at 50 cycles, but II would be OK with 50 cycles for a record breaking battery. I could do a long duration flight each week, for a year. That much flying is just realistic...   How often do you need to break a record of fly an outrageously long time / distance? For everyday flying, you should use a different battery, with faster charge rate and lower price. Fly 10 minutes, land, swap batteries. 

By the way, I changed the props on the T680 from the Tarot 13 x 5,5 to the RVprops 13 x 5.5 , and that reduced my hover current from 31A to 25A . Its not very accurate , next time will measure the watts. But a very good indicator. 

I think I can hover 55 minutes now. The new props have a less aggressive shape at the leading edge and do not have the upward flare at the tip. They also sound quieter in flight. 

Comment by Daniel Allen on March 24, 2014 at 11:07am

Yeah that's what I was talking about. That Tarot (T-motor) style prop is a bad design, even though it looks sweet. The RV prop is more like the DJI style, which is better.

Comment by vova reznik on March 24, 2014 at 12:00pm

The Tarot prop might be more efficient at lower RPM- if you are using a smaller battery and thus less weight.

Comment by vova reznik on March 24, 2014 at 12:01pm

Or an x8 configuration 

Comment by Tipu on March 24, 2014 at 1:12pm

Tommy Larsen 

I am hunting high energy capacity batteries too, I did same thing and found #320 Cells at highest capacity.

but manufacturer confirmed that this mentioned weight is wrong on website.

Though, I am Talking to different vendors.

Melasta.com has a 21Ah cell with 212.88 Wh/kg but that is only 1C. not suitable for any Multicopter i think.

One thing seems very promising, this is 7250mAh cell with 200.19 Wh/kg.

this cell is 1023 in list(PM for list)

But it has same life cycle problem as GEB8043125 cells, this cell has less than 100 life cycles. as mentioned in manual(PM for list)

In last , Panasonic NCR18650B seems solution.

Comment by Tommy Larsen on March 24, 2014 at 3:15pm

@Tipu: I found out that the #320 is 40grams, so still good ratio :)

I sent you a PM regarding the other list.

Comment by Pedals2Paddles on March 25, 2014 at 4:36am

Where did you get the RVprops?  I just did a google search and they do not appear to exist....

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