I just finish my finals! I have a few weeks off before my next intership.
I have a tonne of video to upload because I have been using the scooter a lot!! I have a couple of miles on it. I broke the belt a couple of time and I am right now waiting for a new belt, got 2 this time.
I am also working on a belt tensionner, I realise it is important (but to lazy to build one) since the belt slips a lot due to high torque when starting the scooter.
I bought these new Turnigy Nano-Tech battery from hobby king.
Here are some of the highlight
- Fast charge capable, up to 15C on some batteries.
Longer Cycle Life, almost double that of standard lipoly technology.
- Internal impedance can reach as low as 1.2mΩ compared to that of 3mΩ of a standard Lipoly.
- Less Voltage sag during high rate discharge, giving more power under load.
Since V = RI, and we have a 3mΩ resistance per cell in my standard battery and consume 80Amp at peak.
When you have 14,8V, that is 4 time 3,7V cell. Since they are in series, we should then have a 3mΩ * 4 = 12mΩ for a pack.
V = 0.012A * 80
V = 0,960V of drop out. (960mV)
With the 1.2mOhm
V = 0.0048A * 80
V = 0,384V of drop out. (384mV)
There is a difference of 576mV. 40% difference.
That is theoretical, how does it stand up in real life?
Here are the measurement I got from live test.
82.51A Peak Amp
Nominal Voltage 16.52V and the minimum voltage sag was 15.58V
16.52V-15.58V = 0.940V
0.940V/82.51A = 11.393mΩ
77.83A Peak Amp
Nominal Voltage 15.65V and the minimum voltage sag was 14.71V
15.65V-14.71V = 0.940V
0.940V/77.83A = 12.078mΩ
Test 3 – Going up a steep uphill!
81.04A Peak Amp
Nominal Voltage 16.67V and the minimum voltage sag was 15.37V
16.67V-15.37V = 1.3V
Test 4 – After 1 kilometer
72.85A Peak Amp
Nominal Voltage 15.23V and the minimum voltage sag was 13.95V
15.23V-13.95V = 1.28V
1.28V/72.85A = 17.57mΩ
Test 5 – After 1.36 kilometer
70.03A Peak Amp
Nominal Voltage 15.98V and the minimum voltage sag was 14.88V
15.98V-14.88V = 1.1V
1.1V/70.03A = 15.708mΩ
I realise after looking at those results that in some test I have the initial voltage and some the “after the ride” voltage. That make my result not consistent and semi false.
There is difference between the voltage read at the beginning of the test and the one at the end. In my notes I had some results where I am not sure it that is the voltage are at the beginning or the end of the ride.
I will be careful during my next test.
There is many test to be done again with the new batteries. Can’t wait to see if I spend to much money on those batteries!