Small voltage rise when hovering with Li-Ion pack

ArduCopter Copter 4.3
1

I discovered that I’d been undercharging my 10.5A 6S3P Li-Ion pack.

I thought it required 4.1V per cell - according to the manufacturer, it’s 4.2V

I charged the pack to 4.2V and did a 14 minute hover test to allow the motor thrust hover to reset, and to test the discharge rate.

Much to my surprise, there was a slight rise in voltage a few minutes into the flight.

voltage rise
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I know that under load, Li-Ion batteries can improve discharge rates if the batteries heat up, but at such low loads I was surprised to find evidence of this.

I’m curious to know if anyone is familiar with this phenomena on such a copter.

1 Like
2

That is interesting.
Commanded output and current stays the same.

I’ve seen a reduction in current (rather than a voltage rise) with certain speeds of forward flight, obviously depends on your props and copter. Some sort of lift effect like a traditional heli I suppose.
But I’ve only used LiPos too.

One thing of note: you’ve got quite a physical yaw bias going on. Motors 1 and 2 (CCW) are working much harder than motors 3 and 4 (CW)

3

You’re absolutely right about the yaw.

It seems to be a thing about Hexsoon quad copters with their teardrop arms. All four of mine have the same thing.

The way these arm are mounted there isn’t a way (that I could figure) to align them. My guess is that there’s a slight defect in the plastic mounting blocks.

PXL_20230131_142321054
PXL_20230131_1423210541920×1588 151 KB

4

Since that yaw bias is quite substantial, are you able to swap around some of the arm mounts and motor mounts to get a good combination?

5

That’s a great idea. I’ll have to remember to try that the next time I tear it down. Thanks!