Hey missionctrl - thanks for writing in, and sorry you’re running into issues around the power readings and battery detection.
You’re absolutely right to be suspicious of that power_now value - 41W would be wildly high for a mostly idle Tachyon!
I agree that the system is still reporting telemetry based on a previously attached battery pack, in your case the 3S 9450mAh pack. Saying this, 41W for that would also be insane…
The 3 cell battery pack has more capacity, but it doesn’t have any changes from the 1 cell is terms of charging behaviors or voltage readings - I am going to call shenanigans here on our side.
Here’s what we suggest:
Ignore power_now for now. It looks like it’s reporting incorrectly - maybe due to unit scaling or stale calibration.
Trust the math: Take voltage_now × current_now to calculate actual power draw. Based on your values, the system is pulling about 0.35W, which is totally expected for an idle system.
Power cycle + full charge cycle: Sometimes the fuel gauge will re-learn and recalibrate after a full discharge and recharge. Hopefully this is not what is going on!
Specifically, on the calculation and data:
voltage_now = 4109417 → 4.109417 V
(Value is in microvolts, so divide by 1,000,000)
current_now = -85755 → 0.085755 A
(Value is in microamps, so divide by 1,000,000, and the negative sign just indicates discharge)
Power (W) = Voltage (V) × Current (A)
= 4.109417 V × 0.085755 A
≈ 0.3526 W
We’ll investigate this and have to update - I would expect a bug somewhere / incorrect constant for power_now.
So I do have the 3P battery fitted rather than the 1P. I’ve simply noticed with mine, the battery percentage indicated and the voltage of the cell never line up.
I am quite familiar with lithium batteries and their non linearity. But a cell at 3.4V is not 80% charged, and during the recharge ive seen as wild as it claiming 4.0V to only be 20%. I’ve also three times now hit the automatic shutdown on empty, and not once seen a reported battery percentage lower than 25%. I dont think the calibrations are remotely accurate right now.
Longer term, I would be interested as to whether we can flash new battery settings, I would quite like to use LiFePO4 cells instead if possible, but alas, I have no commercial application here. I am just a nerd with a toy. (fwiw, I am also very familiar with the risks and safety precautions required in battery systems and how unlimited user freedom for battery configuration is also unlimited user freedom to accidentally make a bomb, and I am also willing to wait).
