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State of Charge

3,103 bytes added, 00:25, 1 July 2020
cleanup and update
[[Wikipedia:State_of_charge|State of Charge]] is a calculation meant to help estimate remaining energy in the [[Battery]].

; Concepts
: SoC is a porportional representation; a percentage (fraction), so it is only applicable with a '''known total''' or max.
: Riders all have experienced different ranges under different temperatures, various environmental conditions etc.
: So ''full'' is really a subjective term, like asking ''When is a balloon full? Before it pops? But if you fill it with cold air then move to a warm environment, it pops''.
:* Paraphrase of [ ElectricZen's explanation]
: SoC is most easily calibrated using the battery pack's voltage at rest or near rest.

;[[Battery Voltage]]
: {{:Battery Voltage}}

; (Obsolete) SoC Indications [ per protomech]:
: Before Zero removed pack capacity readout from the [[Official Mobile Application#Statistics_Mode|mobile app]], there were some corroborating indications available:
* The app appeared to simply show kWh using Zero's max capacity rating, i.e. present voltage times present amp hours.
* The voltage and amp-hours were likely to be correct, but the kWh readout was a rough guide at best.
* The percentage reading adjusted to the estimated pack maximum over time, so as the pack aged, the reported Ah and kWh readout would decrease, but not the maximum percentage.

; Variance across Battery Pack Years
* The sensor equipment measuring current and temperature for the battery pack improve over the years, impacting SoC indication.
*: 2017 model year bikes appear to have an increased range of current sensor calibration quality, improving that year's estimations.
* Cell behavior also varies over the years, generally improving in robustness.
*: One can find multiple complaints of going into limp-home mode at 5-15% from 2014 SR owners, for example.

; Variance by riding conditions
* Cell discharge is an electrochemical process that depends on the cells' physical conditions.
* The resistance of the cell (which should be low) increases with environmental factors like temperature.
*: This results in reduced performance, since the resistance lowers the terminal voltage of the cells and the overall battery pack.
* At low SoC values, SoC might drop considerably once the BMS observes low terminal voltage as an indirect result of low temperatures or a cell imbalance.
*: The lowest-performing cell becomes the limiting factor in pack performance at low voltage / SoC, and Zero does not provide indications to help you anticipate or diagnose this.

; Other References
: [ Inaccurate SoC Estimate]
: [ How OEMs calculate Battery Capacity, and why it's not totally their fault they are wrong by Brandon Nozaki Miller]


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