Nead help reading a log

[Francois]

I have an SAB 700, with over 150 flights, for the last 10 or so, after 2 3 min Motor seems to fade downs and stop no more power, batteries still have 50-55% to go.

I don'nt know how to read the data log to find whats going on.

I Have a Quantum QT4530-500 and CC160HV see my log .bmp I don't know what to read to find if it's ESC or motor or settings, which I have not changed anything for the last year....

Thanks for your help

[Xrayted]

Originally Posted by Francois

I have an SAB 700, with over 150 flights, for the last 10 or so, after 2 3 min Motor seems to fade downs and stop no more power, batteries still have 50-55% to go.

I don'nt know how to read the data log to find whats going on.

I Have a Quantum QT4530-500 and CC160HV see my log .bmp I don't know what to read to find if it's ESC or motor or settings, which I have not changed anything for the last year....

Thanks for your help

It would be better to post the real Caste file so we could open it up and see all the details, but at a glance your battery voltage is dropping down in 4 out of the 6 flights to the point its touching your set voltage cutoff point (solid red line), so I'm guessing you are hitting your LVC limit and shutting down.

Your voltage cutoff appears to be set to 36V, so only 3V per cell for a 12S pack. That is a very low value for your packs to be hitting during flight and at the damage point

Your packs may be tired and cant hold voltage anymore and are sagging despite still showing remaining capacity. Seeing the ripple value average for the flights would help here as well, as that is a sign of battery health.

[Francois]

Thanks that make a lot of sense. I look at ripples, and it's .29 ...29%, all my batteries are dying.

[Xrayted]

Originally Posted by Francois

Thanks that make a lot of sense. I look at ripples, and it's .29 ...29%, all my batteries are dying.

Dont look at the peak ripple value. Its completely normal for the ripple to be highest near zero throttle and 50% throttle as the RPM ramps up, so you will always see these high momentary spikes in the graph as the throttle value passes through certain zones. Use the "average" ripple value for the entire flight that is shown for calculation.

The values shown on the graph are not in percent, but in voltage so you need to do a little math.

Packs with ripple less than 5-7% of total pack voltage are good, so in your case max ripple needs to be below 3.5V for a 12S pack.

8-10% is marginal, and over 10% of pack voltage are very bad and could lead to an ESC fire as high ripple is an ESC killer.

[Francois]

To convert voltage ripples value to %, is max voltage/max ripples ? 55.5v/1.32v=38.26%, is that correct ?

[Xrayted]

Originally Posted by Francois

To convert voltage ripples value to %, is max voltage/max ripples ? 55.5v/1.32v=38.26%, is that correct ?

No, just look at the number shown on the graph bottom for your average ripple value.

That number is in volts, so for example if the average ripple value is 5V, and your 12S packs are 50.4V fully charged. You want the ripple to be below 7% of the pack voltage for best battery health, so 50.4V X .07= 3.5V , so you want a ripple value of less than 3.5V for best battery health on a 12S setup

Anything 8-10% of pack voltage is questionable and above 10% absolutely no good and should not be flown

So are you saying that your average ripple is only 1.32V? It certainly doesn't look like it would average that low based on the log you posted up. You shouldn't be hitting 3V per cell in flight ever, as that will damage your packs, and you are dropping that low on most flights so something is going on with your batteries being able to maintain voltage under load.

Check out this example log from my 12S Goblin speed doing some basic sport flight. I have the LVC set the same as you to 36V as I use a timer and never get anywhere near that low value. I'm pulling 176A peaks on this log which are far higher than your max current which barely hits 90A, yet look how much better my voltage is being maintained and not getting anywhere near the LVC line even at twice the current draw as yours.