Jason McNeil Posted August 11, 2015 Share Posted August 11, 2015 Background:Some of the most hotly debated contentious topics with eWheels today are questions like:The manufacturer claims that the sustained power output is (e.g. 1000W) is this true?What is the range if riding at constant velocity of 15kph vs. 20kph or 25kph?Can such concepts as ride-quality be quantified?What factors most influence control-board heat generation? Is this a problem for my eWheel?How much power safety margin is there for my eWheel?Without shunting, how much power can my BMS provide before cutting out? Is the power cut-out a result of hitting the max RPM limit, voltage drop, or BMS cut-out? How efficient is the regenerative braking system, how much power gets dumped to the battery pack?What is the range of voltage swing under various load conditions?How low does the voltage get (under load) for low battery notification? What is the absolute 'get off now' voltage level? Is the capacity of my battery pack really what the manufacturer claims?How fast is my battery pack degrading? Most manufacturers are not prepared, or are not sufficiently skilled, to provide answers to these questions; it is therefore up the eWheel community to find the answers to these questions ourselves. Fortunately there are tools on hand that can help produce the data to answer these, helping to expose widespread exaggeration, deceit & out-right lies. This objective data can also be used to help develop better guidance & recommendations for the user community.Methods: CAUTION: Please use extreme care if planning to carry-out any modifications to your eWheel. If inadvertently shorted, the batteries can cause fire & will almost certainly void any warranty. Do not attempt if you are unfamiliar with electronics & if you are, always triple check polarities connector points. eLogger: the beauty about this system is it can be adapted relatively easily for any eWheel being sold today. The core product is called eLogger, a versatile in-line power monitoring system rated to 80v & over 150A! Parameters are defined from within Windows program, where such aspects as the sample rate, data elements to capture, play-back & some powerful charting options are available. Over the past two weeks since I've been using it, I've found there's some idiosyncrasies & small bugs, but it should be good enough for eWheel data capturing purposes.Sensors: there's about a dozen different sensors available. At the moment, I have several temperature sensors to record the control-board's heat sink, battery pack & BMS. Had some problems with two different RPM sensor, the optical one gets erratic readings in direct sunlight & my magnetic sensor was faulty... The G-Force sensor is interesting for attempting to capture the ride quality over different types of terrain—cobble stones, paving slabs, curbs drops, & pedal tilt. Power Cables & wiring:The eLogger has a default capture rate of 10Hz (10 samples/sec) recording over 5hrs of data & consumes about 11watts when in the power loop. Using XT60 connectors for the interface between the eLogger & eWheel is cheap & practical, allows the recording system to be bypassed without much fuss or hassle. Depending on how much available space & the battery layout, you might have to cut an groove in the side-paneling for the wires as I have done in the KS 800W. Results:Here is an example of a test run on accelerating up an 10° incline at the maximum speed. The most surprising result of this test is that despite a continuous acceleration, the concept of continuous/sustained power doesn't really exist. The power profile is a chaotically spiky in nature. The implications means that the BMS/batteries must be able to cope with very high peak loads. I'll be sharing more data/experiences of this system over the next couple days. Link to comment Share on other sites More sharing options...
esaj Posted August 11, 2015 Share Posted August 11, 2015 That is pretty spiky... for our telemetry-project, we'll probably need to do some averaging/smoothing over the samples to get more readable real-time graphs. Do you think the 800W Kingsong can go over 1300W or is that the peak power? Could be also the maximum continuous output for the batteries, if it's a 16S2P-pack (10A max continuous per pack), as the current seems to be around 20A... Purely judging by eye, it looks like it averages around the 800W nominal power mostly, sometimes spiking higher. Also the voltage drop seems fairly significant over the climb, hopefully they haven't got a "over-sensitive" BMS. Link to comment Share on other sites More sharing options...
Jason McNeil Posted August 11, 2015 Author Share Posted August 11, 2015 Pretty certain there's more power to get out of it beyond 1300W: in a more extreme test I was getting spikes of 1500W. I need to find a 100+kg rider who's willing to push to the extreme Wheel limits I don't think a 5v voltage sag is anything too worry about, will compare this to how much the voltage drops on a 16S1P Wheel. Link to comment Share on other sites More sharing options...
Gimlet Posted August 11, 2015 Share Posted August 11, 2015 You could always weight up a knapsack to the required weight yourself Jason! Link to comment Share on other sites More sharing options...
Daan Posted August 12, 2015 Share Posted August 12, 2015 Very cool! Was it hard to connect the wiring to get the Wattage and Voltage measurements? How expensive would it run to just get those measurements? Link to comment Share on other sites More sharing options...
Jason McNeil Posted August 14, 2015 Author Share Posted August 14, 2015 Base eLogger is only $70, you then buy the sensor's you're looking to measure data for. Link to comment Share on other sites More sharing options...
Flightrider Posted May 19, 2016 Share Posted May 19, 2016 Interesting thread. This is the same e-logger that we use on the R/C Drones that I fly. Link to comment Share on other sites More sharing options...
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