Understanding MambaXLX2 data logs

[ezhitz]

Well we tried a new mamba xlx2 in a Q hydro today it seemed to handle it fine. Running no water cooling yet and the temps were not to bad.
The boat is set up with a Neu 1530 .75y 4400mah 2p test prop was a abc 1916 top speed of 83 mph run on our club pond oval. The boat was 5 mph
faster then when you used the swordfish 220 amp. The fan didn't even come on. What i would like to know is what is a good ripple current reading.
With todays limited testing I'm impressed with the unit.Q-Hydro ABC1916.jpg

[RaceMechaniX]

Ripple voltage is no problem at 0.33V max.

[jkflow]

Ripple should be less than 10% of your applied voltage, 0.33V is very good, but you might be masking your data.
Make sure that you zoom in to the region of interest, i.e. the run itself or just portions of it.
There is a lot of data of interest, and ripple is only a small portion.

Zoom in and post another pic.

[ezhitz]

Here is a zoomed in chart
Q-Hydro.jpg

[jkflow]

Decoding is always a little tricky with a picture, but all I can see is good news. Some items are not obvious.
Big fat red line is your LVC cut-off setting in the ESC, can be turned off and recommended if this could become an issue.
You do not ever want the Voltage(V) to get close or below that line, as the ESC would limit throttle. This run looks fine from that aspect.

Motor Power out (%), you are at 100% for the duration of your run, very good. If you are not at 100% it is typically a throttle range adjust error. - looks ok. Trick here is to not 'squeeze' the trigger like a Hulk when doing the adjust while you are gentle during runs. You will end up at ~95% due to overstimulating during the adjust with plastic bending etc.

Throttle in (ms) - that is how fast/slow you are squeezing your trigger, quick pull causes high Amp draw which results in Voltage (V) to go down. Not really an issue in boat racing but important for cars. A slower pull might result in better acceleration, but we are talking millisecond response time for boats and fingers are difficult to control

Milliamps (mAh) amount of power you sucked out of the Lipo, somewhat unreliable but states 1500mAh, put the Lipo on a charger and compare. This could enable you to use smaller and lighter batteries.

Temperature - ESC temp - no issues, barely noticed the run

Current (A) - note that your peak is when you 'yanked' the throttle, during the run it settled down with max ~200A and lower valleys. My guess here is that the prop cavitates at times (waves), less current but 100% power results in higher RPM. You can use this to determine if you can prop up or down. Seems like you could prop up, based on this data. Lipo and ESC can give you more.

Ripple - super clean, no need to add cap packs. The rule used to be less than 10% of voltage applied. Others take it lower to 5% and you are below that. Another sign you can get more out of the system.

Horsepower - somewhat useless, always follows Voltage and Amps and what matters here is that voltage doesn't drop below LVC. Nice info though, knowing you have 7.5 horses galloping in your hull. Just re-iteration that hulls need to be able to handle this setup.

RPM - shaft RPM=prop RPM. Can be used for picking the right motor kV. 25-35kV I believe is the recommended sweet spot for a prop.

One more note, you can calculate true motor kV at prop by dividing RPM/voltage. Pick a point. Looks like a 1600 kV

Hope it helps.

More info over here, several threads on this topic on that forum, car related though:
https://www.arrmaforum.com/threads/castle-datalog-question.26913/

[LibertyMKiii]

A few notes on navigating the graphs for best results/use of the data.

1. Gearing setup on the default which is 1:1. Robert at Castle explained this to me that the reason relates back to when the logging software was created. It was originally created for RC helicopters and the gearing changes the shaft/rotor speed. Modifying this value would make the RPM numbers change rendering them as useless data.
2. Make sure in the settings that graph smoothing is disabled/off. The smoothing feature will move the numbers a little bit also.
3. Before zooming into a run ensure that the following setting is turned on to avoid clipping off the peak values and potentially skewing the data. (most of the time power output will get clipped)
View > Graph zoom > Vertical Axis Locked.
This will allow you to zoom way into a specific part of the graph and see in fine detail what is going on again with-out having any of the data modified.

I personally turn off a few of the data points in castle link that I don't care about like BEC voltage and mAh consumption, and then turn the sample rate up to 10 samples per second. This gives fine detail in the logs while helping to improve the duration/capacity it can store.

[ezhitz]

Great information thanks for the input guys I will make the changes for the next time .