[Finnster]

Sry Brian, Im not trying to shoot down your idea, but just throw out some considerations. The ideas I have are to create a robust and reliable test method, within reason of course. There is a tradeoff between cost and dependability, but not necc 1:1.

If you create a lot of data, esp say showing a certain well known brand does not perform up to its peer group, the likely consequence will be objections and complaints of the unreliability, misuse or bias in the data. The more robust method you create, the less the argument can be about the trustworthiness or competence of the test method, and more about the results of the data. Ie, it can serve more people. If you are going to go to all that trouble anyway, seems like doing it well and useful to a wide range of people.

Ex: You use a simple resistive device and measure voltage under load. Brand X shows a V drop .2v below its peers.
Is the drop due to higher resistance in the load, inaccuracy of the voltmeter, charged to a diff level, or a misreading by the analyst?
Maybe none, but no way to certify, so data is suspect. Has nothing to do w/ my personal opinions of the analyst, but Brand X supporters will view the cause in deviation in the most negative ways, and lack of robustness of the test cannot resolve the dispute.


FWIW, I am a professional scientist in a heavily regulated industry, so I have some experience with the challenges of creating reliable tests and methods. Its a PITA, but I don't think you need to go so far as all that. I do have a particular critical view of these things however.

What I am proposing shouldn't cost that much, but further cuts could be made at the expense of some dependability and robustness. Minimally I would use a device like an ET to independently collect data electronically. Helps with analysis down the line too.

A independent power source along with a reliable voltmeter shows the test device is working properly before the test was run. Does not have to be a huge amt of power, just something regular and consistent. Turn it on for a light run, collect the data thru an ET, and it serves as verification run. Verification runs should look similar to ea other and be within some tolerance.

I would then just use a ESC and motor like you say, and the motor hooked up to a load. Could be as simple as a propeller, but a spinning weight driven on a pulley would imitate cars more closely. Gearing could also change the load fairly easily, and easy to set. Rather than adding weights, it may be simpler to alter gearing for diff loads for diff sized batts.

Perhaps even a computer PSU would work, as long as its output was consistant.

Set gearing (ie 2:1,) hook PSU up, run verf. run (ie set thr to 10% and let spin up weight to speed.) Hook up batt #1, run full Test Run method (say simple as 100% thr, let level off, then end.) Repeat with batt #2., etc.

A calibrated voltmeter that could read volts at leveling off manually could corroborate ET voltage readings. Ideally this would be recorded electronically, but is beyond the scope of the project.

Verf run shows the profile of the test system. Should be comparable to other runs at same gearing and same PSU. If its fine, then test results are more trustworthy. Then download all the ET data and save into database. You can export ET data to excel (or hopefully better database programs) to create graphs. Draw graphs. If you can export and be able to overlay graphs from multiple batts, all the better.

More robust verf runs can make normalizing the data over time or test sessions easier (or even possible.)

More sophisticated thr programming could make some interesting testing, such as bouncing thr from 25% to 100% over a few secs for a number of cycles to see how well the batts transition. Don't have to do this, but would be cool.

All depends on what's doable and how far you want to go.