|The test equipment:|
The Lipobench was build to enable me to test Lipos for our Racequads reproducible, always within the same conditions. The most importand point was, to make this device independent from any human influence.
The brain of the device is a Arduino with some current, voltage and temperatue sensors for a reliable tracking of all the needed data. It even has a build in Lipo and power supply to be able to deliver clean power to the Arduino without using any power of the tested Lipo. The Arduino and the sensor units are taking care of the test runs.
So every single test will run under the same conditions. Even if i want to test the same Lipo month later to see how it deliveres power after usage.
All Lipo tests are done with batteries at 25°C. It is very important always to have the same temperature!
| The back of the Lipobench:|
The unit with the Arduino and part of the sensors is connected to the power unit with a network cable to control the SSRs and get the current and voltage data.
This enables me to let the unit blow out the heat of the room i´m working in. All the measurement data is written to a SD card by the Arduino, so every single test run creates thousands of data points that are then uploadet to this webside.
The temperature sensor is always strapped to the side of the LiPo, always the same on every tested Lipo. The charts on this website are showing the temperature change of the LiPo while the test is running, not the absolut temperature!
| The load resistors:|
The load resistors are controlled by the Arduino and switched on and of by 4 SSR (Solid-State-Relais) within miliseconds. This enables me to run tests with 15A, 30A, 60A and 80A. The heat of the resistors, while a test is runnning, is distributed by custom made heatsinks and cooled down by three 120mm fans. For security reasons, the case is protecting the resistors inside, so nobody can touch any hot parts of the device.
| Voltcraft VC880 + PC software:|
The calibrated VC880 is used to controll and maintain the Lipobench to make sure the measurements are always the same. It´s also used to support the IR (ESR) measuring.
| Lipobench battery incubator:|
This tempering cabinet with adjustable temperature from 5°C to 60°C (in 1°C steps) + additional thermometer to measure the temperature of the battery itself is really important to be able to measure the IR (ESR) always with the same conditions.
The performance of a Lipo (IR, real C-rate and bursttime etc.) battery is locked to the temperature of the battery. Every degree does change the result. So it´s verry important to start the performance test always at the same temperature, and of course measure the IR (ESR) always at the same temperature.
| Why the temperature matters:|
This is the first test of the termpering cabinet with 4 data points measured from 10°C to 55°C. You can see why it´s so importand to measure always at the same temperatures!
Whenever you see some IR results without the temperature and voltage of the cells, it´s useless!
| The Universal ESR Analysis Meter V2|
This device was created by Wayne Giles to be able to monitor Lipo batteries, and measure the IR (ESR). The ESR of the Lipo, and the ESR of every cell can be measured.
If you are interested in this topic, please visit this page.
|The test procedure of the 80A / 60A & 30A tests:|
| To run a new test, first the Arduino will be switched on and the Lipo for the fans has to be plugged in. Then the Lipo for the test will be connected. At last one of the test cycles, for example 60A, will be selected.|
The Arduino immediately starts writing all the sensor data to the SD card, and is switching on the load resistors according to the test that has been selected. As soon as the voltage drops below 14V, the Arduino is shutting down the load resistors.
Then the Lipo will start to recover, and the voltage will rise again. In case the Lipo has enough power left, it will rise until 15V. As soon as it reaches 15V, the next burst will be started by the Arduino by connecting the load resistors again. Every test is 100% the same, and there is no human influence. If the voltage is below 14V, the load resistors are shut of, so no human reaction time has any influence to the test.
This cycles of bursts and recovering time will run, until the Lipo will not be able to recover back to 15V. The sensor data tracking will continue untill the max. temperature has been reached, and it starts too cool down again.