Closed jharris1993 closed 1 year ago
unfortunately it's impossible to find a voltage level for the new battery that will be reliable, from one battery to the next. So won't fix, because can't fix unless we go to a different battery chemistry.
unfortunately it's impossible to find a voltage level for the new battery that will be reliable, from one battery to the next.
I disagree as this "issue" is true for any battery chemistry. Alan has researched this, (and I have independently confirmed his results), that suggest voltage levels that are appropriate. I was able to use this data to modify the circuitry in the TalentCell batteries to make the "fuel gauge" more accurate.
Of course, these set-points are always only approximations regardless of chemistry.
Background: Modular Robotics/Dexter Industries decided to depreciate the older 8-cell NiMH batteries in favor of a monolithic Li-Ion battery module and dedicated Li-Ion charger module.
As a consequence of all this, (along with possibly other issues), the decision was made to depreciate the 8-cell battery package in favor of a better quality, and safer, Li-Ion battery pack and dedicated charger.
Issue: The originally designed firmware for the GoPiGo robots, including the GoPiGo3, has built-in battery voltage points that trigger:
Unfortunately, these battery voltage points were calibrated based on the discharge curves for a "typical" collection of eight NiMH batteries. Since the Li-Ion battery pack automatically cuts power at a voltage considerably higher that even the NiMH warning threshold, the GoPiGo3 does not have an opportunity to trigger a safety-shutdown. In fact, it does not even reach the "low battery - yellow power LED" warning stage before automatically cutting power.
It is an established fact that un-commanded and spontaneous shutdowns of a system like Raspbian/Linux can seriously corrupt the media and it is firmly established, (and documented on the MR/DI GoPiGo site), that a controlled shutdown is necessary to avoid corruption of the media.
Request/Proposed Solution: The calibration constants for the battery thresholds should be changed to accommodate the new discharge curve of the new Li-Ion batteries.