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<onlyinclude>
The main [[wikipedia:Contactor|contactor]] is a high-capacity relay-operated switch separating the battery's positive side from the bike's propulsion systems.
: It mutually protects the battery and the bike's systems from damaging each other, particularly for rush currents or overcurrent conditions.
;Model
: Contactors for the 2013+ years are [http://www.gigavac.com/catalog/power-products/gx-series GIGAVAC GX-series contactors].
: The 2013 year contactor is not identified, and some reported an occasional failure mode where "contactor welded shut" could occur.
: 2014+ years feature the [http://www.gigavac.com/products/gx11 GX11], which appears to fail safe open by design (SPST-NO) and has had no significant reported issues.
;Location
: The 2013+ power pack contactor is housed within the "dog house", an enclosed area extending from the main power pack enclosure top face at the rear.
: For the [[Zero_Aftermarket#OEM_Power_Tank|Power Tank]] accessory and bricks and long bricks, each enclosure has one contactor operated by the BMS within.
;Behavior
: See [[#Charging_Control_Unit|Charging Control Unit]] and [[#Contactor_Limits|Contactor Limits]].
;Theory ([http://electricmotorcycleforum.com/boards/index.php?topic=7040 ref])
: A contactor is a large relay: it allows a fairly small voltage/current signal to switch a much larger voltage/current.
: It has two sides:
:# The drive/coil side (control).
:# The load (contact) side.
: On the drive/coil side, there's a "kickback" diode which handles the inductive spike caused when the drive to the coil ceases.
:: Without that diode, the energy represented in the magnetic field inside of the coil would have no place to go, so it would cause a voltage spike which can be damaging to components.
:: The kickback diode gives that energy somewhere to go, allowing it to ramp down fairly slowly without a big voltage spike.
: Depending on how the coil side of the contactor is wound, it has a certain current requirement to pull the contactor shut, say 12V @ 100mA, which will be provided by the driving circuitry.
:: There's not necessarily any relationship between the ''coil rating'' and ''contact rating'', except that bigger (higher-current rated) contacts might be heavier and require higher coil current to get the armature to move.
:: The kickback diode only needs to carry this amount of current, regardless of the contact side current.
:: If a 3A kickback diode is specified for that contactor, it will be adequate for any contact side current.
: The ''make/break'' current is the rating for the contact side of the contactor.
:: You won't actually want to make or break the contactor under the limiting conditions (you'll always want to both make and break the contactor at exactly 0 amps), but in an emergency, it's rated to do so without the contacts welding together -- and an emergency is what the contactor is there for.
: In automotive use, you often see the coil set up for 12V, drawing maybe 100mA (the current can vary widely though).
:: That small current pulls the contacts together, which switches on the high-current side.
====Contactor Limits====
Zero's effective contactor limit for the charging rate is 95% of 1[[C-Rate|C rate]].
The BMS will open the contactor for the following conditions:
;Inactivity
: If the motorcycle is keyed off and not otherwise set in charging mode, the contactors will open after a few seconds.
: If the motorcycle is keyed on and not otherwise set in charging mode, and then 30 minutes pass without control input.
:: Twisting the throttle is sufficient to reset this timer; otherwise restart charging once it happens.
;Voltage
: Voltage is too low or too high outside its safe operating range.
: If voltage is too high (117V):
:# Confirm with the Zero mobile application
:# Attempt to bring it back to normal range by discharging the battery:
:#* operating the motor (fastest but requires a closed contactor, and the Sevcon won't operate above 118V) or:
:#* turning on all available electrical loads.
: If voltage is too low, charge by any means necessary:
:: Prefer the onboard charger or an equivalent rate source through the charging port.
:: In an emergency, the regen feature can be used to charge the battery through the motor.
::: Drive the motor by spinning the rear axle with a suitable power source, with the bike in Custom Mode with regen set to 100%.
;Power
: Incoming power exceeds 1[[C-Rate|C rate]] continuously for a minute. A 1[[C-Rate|C rate]] charges the battery fully in 1 hour.
: For a battery with 13 kWh max capacity, this value will be 11.4 kWh nominal / 102V = 110A (say).
: If the charge rate is too high for the battery, downgrade the charge rate manually and restart.
: Field testing indicates that the short time setting for the contactor opening is 30 seconds, and that a 20 second period under that limit will reset it.
:: This may vary due to environmental conditions like ambient temperature.
;[[Battery Temperature Limits|Temperature]]
: If the battery temperature (not ambient) is outside safe operating bounds:
{{:Battery Temperature Limits}}
: The Zero battery will emit heat while its charging rate exceeds 4 kW, and it will cool if under that threshold.
: If temperature is out of safe range, do whatever is appropriate to bring the temperature back in range.
;Calculating Contactor Limit Per Bike
Per Zero's specs pages:
: Maximum capacity (kWh) = COUNT(cells) × (cell capacity rating (Ah)) × MAX(cell rating (V))
;Example
: A 2015 SR w/ Power Tank has 15.3kWh max, 13.5 kWh nominal, with a 102V nominal voltage, so is nominally rated at 133 Ah.
: 1C rate means that it can charge at up to 133A.
: At 10% actual SOC (3.4 volts per cell), 1C = 3.4 volts per cell × 28 cells in series × 133 A = 12.7 kW.
: At 95% SOC (4.1 volts per cell), 1C = 4.1 volts per cell × 28 cells in series × 133 A = 15.3 kW.
: These are DC power ratings; AC input power will read 10 to 20% higher (due to conversion losses).
;Contactor Limit Per [[Zero_Aftermarket#OEM_Power_Tank|Power Tank]] or module
: The current capacity will be proportional to the number of bricks vs 4 providing a scaling factor.
: Or, more directly, the Ah rating on the label indicates the 1C rate.
{| class="wikitable sortable"
|+ Charging Limits
!colspan="3"|
!colspan="2"|Capacity (kWh)
!colspan="2" class="unsortable"|Voltage
!Capacity
!Contactor Limit
|-
!Year
!Cell
!# Bricks
!Max
!Nominal
! class="unsortable"|Max
! class="unsortable"|Nominal
!(Ah or 1C amps)
!A (95% assumed)
|-
|2013
|rowspan="2"|25Ah
|rowspan="2"|4
|rowspan="2"|11.4
|rowspan="2"|10.0
|rowspan="6"|116.4
|rowspan="6"|102
|rowspan="2"|98
|rowspan="2"|93
|-
|2014
|-
|2015
|27Ah
|4
|12.5
|11.0
|108
|103
|-
|2016
|rowspan="2"|29Ah
|rowspan="2"|4
|rowspan="2"|13.0
|rowspan="2"|11.4
|rowspan="2"|112
|rowspan="2"|107
|-
|2017
|-
|2018
|32Ah
|4
|14.4
|12.6
|125?
|119?
|}
</onlyinclude>
[[Category:HV Component]]
The main [[wikipedia:Contactor|contactor]] is a high-capacity relay-operated switch separating the battery's positive side from the bike's propulsion systems.
: It mutually protects the battery and the bike's systems from damaging each other, particularly for rush currents or overcurrent conditions.
;Model
: Contactors for the 2013+ years are [http://www.gigavac.com/catalog/power-products/gx-series GIGAVAC GX-series contactors].
: The 2013 year contactor is not identified, and some reported an occasional failure mode where "contactor welded shut" could occur.
: 2014+ years feature the [http://www.gigavac.com/products/gx11 GX11], which appears to fail safe open by design (SPST-NO) and has had no significant reported issues.
;Location
: The 2013+ power pack contactor is housed within the "dog house", an enclosed area extending from the main power pack enclosure top face at the rear.
: For the [[Zero_Aftermarket#OEM_Power_Tank|Power Tank]] accessory and bricks and long bricks, each enclosure has one contactor operated by the BMS within.
;Behavior
: See [[#Charging_Control_Unit|Charging Control Unit]] and [[#Contactor_Limits|Contactor Limits]].
;Theory ([http://electricmotorcycleforum.com/boards/index.php?topic=7040 ref])
: A contactor is a large relay: it allows a fairly small voltage/current signal to switch a much larger voltage/current.
: It has two sides:
:# The drive/coil side (control).
:# The load (contact) side.
: On the drive/coil side, there's a "kickback" diode which handles the inductive spike caused when the drive to the coil ceases.
:: Without that diode, the energy represented in the magnetic field inside of the coil would have no place to go, so it would cause a voltage spike which can be damaging to components.
:: The kickback diode gives that energy somewhere to go, allowing it to ramp down fairly slowly without a big voltage spike.
: Depending on how the coil side of the contactor is wound, it has a certain current requirement to pull the contactor shut, say 12V @ 100mA, which will be provided by the driving circuitry.
:: There's not necessarily any relationship between the ''coil rating'' and ''contact rating'', except that bigger (higher-current rated) contacts might be heavier and require higher coil current to get the armature to move.
:: The kickback diode only needs to carry this amount of current, regardless of the contact side current.
:: If a 3A kickback diode is specified for that contactor, it will be adequate for any contact side current.
: The ''make/break'' current is the rating for the contact side of the contactor.
:: You won't actually want to make or break the contactor under the limiting conditions (you'll always want to both make and break the contactor at exactly 0 amps), but in an emergency, it's rated to do so without the contacts welding together -- and an emergency is what the contactor is there for.
: In automotive use, you often see the coil set up for 12V, drawing maybe 100mA (the current can vary widely though).
:: That small current pulls the contacts together, which switches on the high-current side.
====Contactor Limits====
Zero's effective contactor limit for the charging rate is 95% of 1[[C-Rate|C rate]].
The BMS will open the contactor for the following conditions:
;Inactivity
: If the motorcycle is keyed off and not otherwise set in charging mode, the contactors will open after a few seconds.
: If the motorcycle is keyed on and not otherwise set in charging mode, and then 30 minutes pass without control input.
:: Twisting the throttle is sufficient to reset this timer; otherwise restart charging once it happens.
;Voltage
: Voltage is too low or too high outside its safe operating range.
: If voltage is too high (117V):
:# Confirm with the Zero mobile application
:# Attempt to bring it back to normal range by discharging the battery:
:#* operating the motor (fastest but requires a closed contactor, and the Sevcon won't operate above 118V) or:
:#* turning on all available electrical loads.
: If voltage is too low, charge by any means necessary:
:: Prefer the onboard charger or an equivalent rate source through the charging port.
:: In an emergency, the regen feature can be used to charge the battery through the motor.
::: Drive the motor by spinning the rear axle with a suitable power source, with the bike in Custom Mode with regen set to 100%.
;Power
: Incoming power exceeds 1[[C-Rate|C rate]] continuously for a minute. A 1[[C-Rate|C rate]] charges the battery fully in 1 hour.
: For a battery with 13 kWh max capacity, this value will be 11.4 kWh nominal / 102V = 110A (say).
: If the charge rate is too high for the battery, downgrade the charge rate manually and restart.
: Field testing indicates that the short time setting for the contactor opening is 30 seconds, and that a 20 second period under that limit will reset it.
:: This may vary due to environmental conditions like ambient temperature.
;[[Battery Temperature Limits|Temperature]]
: If the battery temperature (not ambient) is outside safe operating bounds:
{{:Battery Temperature Limits}}
: The Zero battery will emit heat while its charging rate exceeds 4 kW, and it will cool if under that threshold.
: If temperature is out of safe range, do whatever is appropriate to bring the temperature back in range.
;Calculating Contactor Limit Per Bike
Per Zero's specs pages:
: Maximum capacity (kWh) = COUNT(cells) × (cell capacity rating (Ah)) × MAX(cell rating (V))
;Example
: A 2015 SR w/ Power Tank has 15.3kWh max, 13.5 kWh nominal, with a 102V nominal voltage, so is nominally rated at 133 Ah.
: 1C rate means that it can charge at up to 133A.
: At 10% actual SOC (3.4 volts per cell), 1C = 3.4 volts per cell × 28 cells in series × 133 A = 12.7 kW.
: At 95% SOC (4.1 volts per cell), 1C = 4.1 volts per cell × 28 cells in series × 133 A = 15.3 kW.
: These are DC power ratings; AC input power will read 10 to 20% higher (due to conversion losses).
;Contactor Limit Per [[Zero_Aftermarket#OEM_Power_Tank|Power Tank]] or module
: The current capacity will be proportional to the number of bricks vs 4 providing a scaling factor.
: Or, more directly, the Ah rating on the label indicates the 1C rate.
{| class="wikitable sortable"
|+ Charging Limits
!colspan="3"|
!colspan="2"|Capacity (kWh)
!colspan="2" class="unsortable"|Voltage
!Capacity
!Contactor Limit
|-
!Year
!Cell
!# Bricks
!Max
!Nominal
! class="unsortable"|Max
! class="unsortable"|Nominal
!(Ah or 1C amps)
!A (95% assumed)
|-
|2013
|rowspan="2"|25Ah
|rowspan="2"|4
|rowspan="2"|11.4
|rowspan="2"|10.0
|rowspan="6"|116.4
|rowspan="6"|102
|rowspan="2"|98
|rowspan="2"|93
|-
|2014
|-
|2015
|27Ah
|4
|12.5
|11.0
|108
|103
|-
|2016
|rowspan="2"|29Ah
|rowspan="2"|4
|rowspan="2"|13.0
|rowspan="2"|11.4
|rowspan="2"|112
|rowspan="2"|107
|-
|2017
|-
|2018
|32Ah
|4
|14.4
|12.6
|125?
|119?
|}
</onlyinclude>
[[Category:HV Component]]
