Discovery
In go_power.h, lines 422-424, the values that are being defined for use to stop battery charging and resume battery charging based on temperature thermal excursions are quite high. Most lithium-based cells should not be charged above 40C / 104F. Cells that are exposed to temperatures above 60C / 140F may suffer damage or severe degradation. I haven't been able to find the exact specification for the cell being used; perhaps it is one that is qualified for use in thermal extremes, but these values may result in the battery experiencing a severely shortened lifespan, or worse, contribute to a thermal runaway condition if used in environments where repeatedly subjected to these temperatures.
Expected behavior
A Li-Ion or Li-Poly battery should not be allowed to charge in high temperature environments above 40C, and should not be discharged in extreme high temperature environments above 55C.
Actual behavior
The battery is allowed to charge in high temperature environments up to 50C, and discharge in extreme high temperature environments up to 60C.
Steps to reproduce
Review of implemented code.
https://github.com/Open-Air-Foundation/oaf-fw-core/blob/96f7239e00cbd27ed8c7c98fbaf6bbee4ac9db17/products/go/main/go_power.h#L422
Proposed Changes
Low the threshold values down to the following:
static constexpr int16_t OT_CHARGE_HOT_CUTOFF_C = 45;
static constexpr int16_t OT_CHARGE_HOT_RESUME_C = 43;
static constexpr int16_t OT_SHIP_THRESHOLD_C = 50;
If it is needed for the device to continue operate above 50C, then the cell needs to be specifically sourced and qualified for use in that environment.
Discovery
In go_power.h, lines 422-424, the values that are being defined for use to stop battery charging and resume battery charging based on temperature thermal excursions are quite high. Most lithium-based cells should not be charged above 40C / 104F. Cells that are exposed to temperatures above 60C / 140F may suffer damage or severe degradation. I haven't been able to find the exact specification for the cell being used; perhaps it is one that is qualified for use in thermal extremes, but these values may result in the battery experiencing a severely shortened lifespan, or worse, contribute to a thermal runaway condition if used in environments where repeatedly subjected to these temperatures.
Expected behavior
A Li-Ion or Li-Poly battery should not be allowed to charge in high temperature environments above 40C, and should not be discharged in extreme high temperature environments above 55C.
Actual behavior
The battery is allowed to charge in high temperature environments up to 50C, and discharge in extreme high temperature environments up to 60C.
Steps to reproduce
Review of implemented code.
https://github.com/Open-Air-Foundation/oaf-fw-core/blob/96f7239e00cbd27ed8c7c98fbaf6bbee4ac9db17/products/go/main/go_power.h#L422
Proposed Changes
Low the threshold values down to the following:
static constexpr int16_t OT_CHARGE_HOT_CUTOFF_C = 45;
static constexpr int16_t OT_CHARGE_HOT_RESUME_C = 43;
static constexpr int16_t OT_SHIP_THRESHOLD_C = 50;
If it is needed for the device to continue operate above 50C, then the cell needs to be specifically sourced and qualified for use in that environment.