Automatic DC resistance compensation
The uneven charge and discharge from non-collocated batteries within an HMD can be solved by monitoring the DC current on the paths coupled to the first battery and the second battery and making an adjustment in the path resistance to equalize, or at least reduce, the difference between the currents on the two paths. Aspects of the technology described herein monitor current on paths from two or more non-collocated batteries. When the currents are different, resistance is dynamically added to the path with the higher current to equalize the current in the two paths. The monitoring and resistance adjustment can occur during discharge from a battery to a load and during battery recharge.
1. A computer-implemented method for regulating DC current received from two or more non-collocated batteries within a head-mounted display, the method comprising:
receiving a first signal describing a first amperage for a first DC current in a first path that is conductively connected to a first battery within the head-mounted display;
receiving a second signal describing a second amperage for a second DC current in a second path that is conductively connected to a second battery within a head-mounted display;
determining that an amperage difference between the first amperage and the second amperage is greater than a threshold amperage;
in response to said determining, sending a signal to a hardware component electrically coupled to the first path with an instruction to add a first amount of resistance to the first path; and
dynamically adding, by the hardware component, the first amount of resistance in the first path to decrease the first amperage to a first adjusted amperage that is less than the threshold amperage difference from the second amperage.
2. The method of claim 1 , wherein the first battery and the second battery are located more than six inches apart.
3. The method of claim 1 , wherein the hardware component is a field-effect transistor (FET) associated with the first path, the signal causing the first amount of resistance across the FET.
4. The method of claim 1 , wherein the method further comprises storing the amperage difference as an entry in a data store, the entry having a time when the amperage difference was detected.
5. The method of claim 1 , wherein the method further comprises:
calculating a trend of amperage differences between the first path and the second path over time; and
generating an alarm when the trend indicates an increasing internal resistance across either the first battery or the second battery.
6. The method of claim 1 , wherein the first battery is located on a right side of the head-mounted display and the second battery is located on a left side of the head-mounted display.
7. The method of claim 1 , wherein the first DC current and the second DC current are supplied by a charging mechanism.
8. The method of claim 1 , wherein the amperage difference is determined by a microcontroller.
9. A head-mounted display comprising:
a first battery coupled to a first path serving a load;
a second battery coupled to a second path serving the load; and
a current compensation controller coupled to both the first path and the second path before the first path and the second path connect to the load, the current compensation controller comprising a first current sensor coupled to the first path, a second current sensor coupled to the second path, a first dynamic resistor coupled to the first path, and a second dynamic resistor coupled to the second path, wherein the first dynamic resistor is a field-effect transistor (FET), wherein the current compensation controller comprises a microcontroller programmed to calculate an amperage difference between a first current in the first path and a second current of the second path, and wherein the microcontroller is further programmed to send a signal to the first dynamic resistor with an instruction to add a first amount of resistance to the first path in order to decrease the amperage difference.
10. The head-mounted display of claim 9 , wherein the current compensation controller stores the amperage difference as an entry in a data store, the entry having a time when the amperage difference was detected.
11. The head-mounted display of claim 10 , wherein the microcontroller is further programmed to regulate a resistance provided by the first dynamic resistor and a resistance provided by the second dynamic resistor to decrease an amperage difference between a first current in the first path and a second current of the second path.
12. The head-mounted display of claim 10 , further comprising a data store configured to store amperage difference entries, and wherein the microcontroller is further programmed to generate log entries of amperage differences.
13. The head-mounted display of claim 10 , wherein the first battery is located on a right side of the head-mounted display and the second battery is located on a left side of the head-mounted display.
14. The head-mounted display of claim 9 , wherein the load is a processor.
15. The head-mounted display of claim 9 , wherein the first dynamic resistor is a field-effect transistor (FET).
16. One or more computer storage media having computer-executable instructions embodied thereon that, when executed by a head-mounted display, causes the head-mounted display to perform a method for regulating DC current received from two or more non-collocated batteries within the head-mounted display, the method comprising:
receiving a first signal describing a first amperage for a first DC current in a first path that is conductively connected to a first battery within a head-mounted display, the first path providing power to a processor within the head-mounted display;
receiving a second signal describing a second amperage for a second DC current in a second path that is conductively connected to a second battery within a head-mounted display, the second path providing power to the processor within the head-mounted display;
determining that a difference between the first DC current and the second DC current is greater than a threshold difference; and
in response to said determining, sending a signal to a hardware component electrically coupled to the first path with an instruction to add a first amount of resistance to the first path,
dynamically adding, by the hardware component, a first amount of resistance in the first path to decrease the first DC current to a first adjusted DC current that is less than the threshold difference from the second DC current.
17. The media of claim 16 , wherein the first battery is located on a right side of the head-mounted display and the second battery is located on a left side of the head-mounted display.
18. The media of claim 16 , wherein the hardware component is a to a field-effect transistor (FET) associated with the first path, the signal causing the first amount of resistance across the FET.
19. The media of claim 16 , wherein the method further comprises storing the current difference as an entry in a data store, the entry having a time when the current difference was detected.
20. The media of claim 16 , wherein the method further comprises:
calculating a trend of amperage differences between the first path and the second path over time; and
generating an alarm when the trend indicates an increasing internal resistance across either the first battery or the second battery.