Just got a data logger

[johnrobholmes]

I picked up an EagleTree V3 logger yesterday, and they should just name it the battery tester. My last logger went on the fritz and started loosing data during big amp spikes.

I have been tooling around with the sidewinder and 4600 motor lately, and decided to give my system a test at 10hz. That is the fastest sampling rate of the V3. First test was a 3 cell 10C polyRC 4 a/h pack. It made the XX buggy haul ass, and I just did some speed runs for a few minutes. Came back in to read the data and the battery did not hang. On one 38amp max burst it sagged to 8.8v. Pack not good enough, and I can't see any signs of swelling. The rating is no longer valid on the pack to me.

Second test was with an old pack of matched gp3700's. Speed wasn't too crazy, and I noticed that it was fading hard. Must be a bad cell in there. Went back to check the data and I had some big amp spikes, the largest was 48.15 amps @ 340W. The voltage sagged down to 7.06v, not good for a 7 cell pack less than a minute into the run. Time to do some voodoo on the pack and bring it back to life I guess. The twin to this pack was doing much better, so I will test it next.

Lesson learned, don't go for so long without a logger again. I want to get the pro version so I can have a higher sample rate. I bet the bursts were actually higher. I got the V3 because it has an LCD screen that can show data live. Perfect for my electric bike I am building.