|Mar 31, 2013, 09:10 PM|
HobbyKing small Cylindrical LiPo cells
HobbyKing recently introduced a variety of “Round LiPos” to the Nano Tech range, including some small cells in the 80, 90, 130, 180 mAh sizes. They are rated on the label at 15C and mercifully HobbyKing don’t even bother with a fictional “burst” rate.
Here’s part of the blurb.
Advantages over traditional Lipo batteries;
-Power density reaches 7.5 kw/kg.
-Less Voltage sag during high rate discharge, giving more power under load.
-Internal impedance can reach as low as 1.2mΩ compared to that of 3mΩ of a standard Lipoly.
-Greater thermal control, pack usually doesnt exceed 60degC
-Thickness swelling during heavy load doesnt exceed 5%, compared to 15% of a normal Lipoly during heavy load.
-Higher capacity during heavy discharge. More than 90% at 100% C rate.
-Fast charge capable, up to 15C on some batteries.
-Longer Cycle Life, almost double that of standard lipoly technology
Here is the link to the 130mAh cell
I was curious to see how these bare cylindrical cells would stack up against the well respected Hyperion 25C which I tested as part of my thread on the 160mAh sizes back in Oct 2010 and which is my standard 1S cell.
The 130mAh round cell comes with just some light weight sleeving to identify +Ve and -Ve and solder tabs on each end. Adding a Molex Picoblade and wires and some heat shrink to anchor it all I got the following:
Without any wires the Turnigy weighs 3.48g
The Hyperion is currently $6.95 at Aircraft-World and the Turnigy $1.20 at HobbyKing.
Here’s the result for the Turnigy at four different rates. You can see that the 15C label is just about justified. It holds 3.4V but only delivers 91 mAh even with an unrealistic 2.8V cut off. At 18C it is totally out of the game. The almost identical temp rise slopes at 12,15 and 18C is interesting.
See Graph 1
Comparing the two cells at 10C (1.3A constant current) and 15C (2.0 Amps) the Turnigy does pretty well. Cell voltage is the solid line measured on the LH axis and Temperature the dotted one measured on the RH axis. I wouldn’t put too much reliability on the accuracy of the measured temperature since the sensor is just held to the surface of a cylindrical cell but allowing for the fact ambient temperatures were a couple of degrees different, the Turnigy is showing a very low temperature rise and a flatter voltage curve with higher capacity than the Hyperion at the 10C rate. At 10C it is just getting into the voltage dip region that indicates significant cell heating but the actual temperature rise is small and at the price any effect on cell life is irrelevant. At 15C it is struggling with a pronounced voltage dip before self heating lifts the cell voltage to virtually the same as the Hyperion but it is delivering far less capacity. From previous tests I know the Hyperion can just manage 20C – it is possible the newer range of Hyperion cells do better.
See graph 2
Up to 10C (1.3A) these new Turnigy Cylindrical cells are virtually as good as the Hyperion for voltage, have more capacity, are significantly lighter and are a lot cheaper. Most of my indoor flying is done at less than 10C rates. At currents over that the Hyperion is superior.
They look like they would have a lot of possibilities, particularly if you don’t want to use the Molex Picoblade connector or want to build a small 2S pack.
I also tested a Turnigy round 180mAh cell, which weighs 4.4g with connector.
The graph tells the story. At 10C it delivered only 124 mAh with a slightly inferior voltage curve to the 130 mAh at the same rate! Maybe I got the ugly one of the litter.
See Graph 3
|Mar 31, 2013, 09:40 PM|
Joined Nov 2000
I've learned over Many Years... to first wean myself from 'round cells'... then to detest them.
NO interest whatsoever in revisiting those...
regardless of Brochure Babblings.
|Mar 31, 2013, 09:49 PM|
So you have some facts to support that stance? Just curious that's all.
I wasn't suggesting for a moment the brochure babblings were true - that's why I call it blurb.
I've learnt over the years to rely on reputable test results - not strongly held opinions.
|Sep 17, 2014, 01:21 AM|
jj604, Have you tested the bigger capacity Turnigy 1s batteries like the 1200mah round cells? They are used very often in DLGs where we need 1s and average discharge of around 200 to 400mah and big capacity.
I have been doing some discharge curves but getting quite a bit different discharge curves with the same size and rating cells. I am using Align JST connectors which the quality of is up for debate. The wire is very rigid and definitely not silicone covered wire. Maybe one of my JST connectors is bad or something but I doubt it. The thing that makes me a bit worried about the graph accuracy is on pic #1 where the voltage drop changes. I must have had a bad connection or something in the JST connector or the hyperion had an issue during the discharge. I need to buy some better quality JST connectors to test with or just solder wires directly to a bigger connector like a big deans to rule out connections as an issue and use better wire.
I am only testing down to 3.6v for Rx voltage safety reasons. I realize that this means I will not be testing the cells to make sure they deliver all of the capacity as a much lower voltage under higher amp loads would allow to get much more mah out of the battery. For my testing though I don't want a voltage lower than 3.6v.
I was hoping to find some testing from someone that has a better test setup than me with my hyperion charger and cheap connectors.
Battery1 is a used battery in a DLG (300mah average discharge probably during it's normal operating life) but I drained it all the way to 1v and brought it back from the dead to keep using it. You can see that it's capacity is reduced at a 200mah draw. Battery2 is a brand new battery never used yet except for testing. It has more capacity but it drops in voltage even quicker than the old abused battery.
This is the data I have...
battery1 used and abused
Turnigy 1s 1200mah round LiPo cells
Pic1: battery1 discharge 200ma
Pic2: battery1 discharge 500ma
Pic3: battery1 discharge 1000ma
Pic4: battery2 discharge 200ma
Pic5: battery2 discharge 500ma
Pic6: battery2 discharge 1000ma
|Sep 17, 2014, 03:53 AM|
Sorry, I have not tested anything like those packs. I was only interested in the tiny 160mAh round cells as an alternative to the typical lozenge cells of that size.
I have seen voltage traces similar to your first graph on individual cells in larger packs while using the Hyperion. It was always dirty balance connectors and Deoxit fixed it. You might want to try that first before you go any further. Picture 6 is typical of a dirty contact as well.
I'm assuming you are getting the voltage and current traces from the main power connection? Or are you using a separate balance connection to measure the cell voltage? I haven't used a Hyperion with the software suite for a long time and cannot recall how it plots a single cell load.
|Sep 17, 2014, 04:28 AM|
These are HK Turnigy 1s round LiPo batteries that I have to solder the JST connectors onto. They have soldering tabs.
Now that I think about it I did discharge the battery #1 on accident by shorting it for several seconds. I am pretty sure I used the same JST connector for both 1200mah tests. That is more than likely the cause. The 900mah battery test below used a new JST connector and did better than both of the 1200 cells on the 1000ma discharge which seems to go along with that. That glitch in the first discharge curve really had me confused and I remember moving the connector around trying to make it happen again but couldn't but I guess it still could be the connector.
I did these tests about 2 months ago and have been scratching my head trying to interpret the results. I need to do them again and buy some new JST connectors instead of reusing old ones for testing. Thanks for the feedback!
Turnigy 1s 900mah 15C round cell LiPo
Pic1: battery3 500mah discharge
Pic2: battery3 1000mah discharge
|Sep 17, 2014, 05:32 AM|
OK, with only a power wire connection the voltage the Hyperion is measuring includes the resistance drop of the wires and all connectors. I'm betting if you had good clean connectors the bumps will disappear.
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