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Limiters Accuracy Test during Tenshock Poland Cup 2017 in Lesznowola

During Tenshock Poland Cup 2017 in Lesznowola we carried out measurements of accuracy of the limiters available on the market. We tested MDLE4, eLim and KLW202. In case of MDLE4 we set the limit value 53 Wh and connected a servo in place of ESC to observe when limit has occurred. In case of eLim and KLW202 we observed results shown on their displays. As a power source we used a LiPo battery 3S and as a load, electronic load connected in series with light bulbs. We used constant current with value 48 A and modulated current from 30 A to 60 A with period 5 s.

The energy in the circuit is defined by following formula:

 

The oscilloscope calculated the power curve by multiplying the voltage and current curve. Then calculated the area under the power curve (integrates the power curve) giving result in Ws (watt-second).

Equipment:

  • Yokogawa DL2700 Long Memory Digital Oscilloscope, 12 bit resolution (after box average processing), 1,5 % DC accuracy, 200 sample/sek

  • Norma Mod. 60P Shunt Resistor, 0,1%, 1500 A, 60 mV

  • Prcision amplifier to amplify the signal from the shunt resistor

  • Electronic load with range 0 – 100 A

  • Signal Generator to modulate load, sinusoidal wave

  • Suitcase with light bulbs from Michał Hoffa

  • Battery 3S

Results:

Constant current:

Device type Device result Oscilloscope result Error
KLW202 38,1 Wh 38,36 Wh -0,68 %
eLim 2870 Wmin 2766 Wmin +3,8 %
MDLE4 sn: 3H042 53 Wh 48,32 Wh +9,7 %

Modulated current:

Device type Device result Oscilloscope result Error
KLW202 49,8 Wh 49,93 Wh -0,26 %
eLim 2264 Wmin 2203 Wmin +2,8 %
eLim 3451 Wmin 3116 Wmin +10,8 %
MDLE4 sn: 3H029 53 Wh 50,31 Wh +5,4 %
MDLE4 sn: 3H040 53 Wh 47,93 Wh +10,6 %
MDLE4 sn: 3H040 53 Wh 48,09 Wh +10,2 %
MDLE4 sn: 3H028 53 Wh 47,23 Wh +12,2 %

Printed screenshots from oscilloscope, CH1 - voltage (2V/div), CH2 - current (10A/div), MATH1 - power (125W/div), MATH1 IntTY1 - energy Ws:

Constant current:






Modulated current:














Thanks to Maciej Kozłowski for the invitation and organization of a great event.


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