CAPACITOR (i-ELOOP) [i-ELOOP]

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Purpose, Function

Construction

•  The capacitor (i-ELOOP) is located behind the front over fender (LH).

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Part name	Purpose
Service plug	Interrupts short-circuit current to prevent a short to the 24.3 V related electricity stored in the capacitor (i-ELOOP) during servicing and the flow of large amounts of current.
Temperature sensor	Detects the capacitor (i-ELOOP) temperature for the purpose of assuring capacitor (i-ELOOP) performance because capacitor (i-ELOOP) performance deterioration is caused by a continuous capacitor (i-ELOOP) high temperature.
Capacitor (i-ELOOP) relay	Switches the electric circuit when the ignition is switched off, when in pre-charge mode for i-ELOOP operation, if the vehicle is in a collision, and when it is in fail-safe.
Plug (for compulsory discharge)	Equipped to the resistor on the capacitor (i-ELOOP) so that it can be disposed of after discharging the capacitor (i-ELOOP) for the purpose of assuring safety. The capacitor (i-ELOOP) can be transported safety by the compulsory discharge of the capacitor (i-ELOOP) using the resistor.
LED	Turns on the LED during compulsory capacitor (i-ELOOP) discharging.

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•  The capacitor (i-ELOOP) input/output terminals are as follows.

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Terminal signal	Input/output
2A	Power input from generator.
3A	Electricity output to DC-DC converter (i-ELOOP).
1A	Temperature sensor signal output to DC-DC converter (i-ELOOP).
1E	Electricity output to DC-DC converter (i-ELOOP).
1F	GND (Temperature sensor)
1G	Electricity output to DC-DC converter (i-ELOOP).
1I	Electricity input/output to DC-DC converter (i-ELOOP).
1J	Electricity input/output to DC-DC converter (i-ELOOP).

Operation

Capacitor (i-ELOOP) power

•  The capacitor (i-ELOOP) can be fully charged in approx. 7—10 s depending on the capacitor (i-ELOOP) voltage or vehicle conditions when decelerating from a speed of 40 km/h {25 mph} or more.

•  If the capacitor (i-ELOOP) voltage is lower than the battery voltage, power cannot be supplied to the vehicle’s electrical devices. Therefore, the actual capacitor (i-ELOOP) voltage that can be used is the voltage approaching the battery voltage.

•  The time in which power can be supplied to the vehicle’s electrical devices after the capacitor (i-ELOOP) is fully-charged, changes depending on the vehicle’s electric load.

Ex.) Capacitor (i-ELOOP) voltage and power supply time relation

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Capacitor (i-ELOOP) charge/discharge principles

•  The capacitor (i-ELOOP) stores electricity using an electric double layer^*2 instead of a dielectric^*1 consisting of a condenser.

Charging

―  The electrolyte consists of cations and anions, and when the battery is connected, the anions are attracted to the positive electrode of the activated carbon and the cations are attracted to the negative electrode, and each charge layer (electric double layer) is formed on the surfaces where the electrode and the electrolyte contact. Ions are absorbed physically on the electrode surface of the activated carbon by attracting electrical charge in the activated carbon and the ions in the electrolyte, and electricity can be stored even without chemical reactions.

Discharging

―  When the resistor (load) is installed, current flows by separating ions from the activated carbon (electrode). Ions are diffused to the electrolyte because the electrical charge in the activated carbon (electrode) is lost through discharging.

Note

•  The condenser capacity used for the general electrical circuit is several picofarad to tens of thousands of microfarad. However, a high-capacity electrical double layer capacitor (i-ELOOP) of several F to 200 F can be stored.

•  A lead battery or lithium-ion battery stores electricity using chemical reactions. However, because the capacitor (i-ELOOP) stores electricity by physical phenomenon and the electrode deterioration is extremely low, it has an excellent service life.

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Capacitor (i-ELOOP) relay operation

•  The capacitor (i-ELOOP) relay switching is controlled by the DC-DC converter (i-ELOOP).

•  The capacitor (i-ELOOP) relay disconnects the capacitor (i-ELOOP) power from the vehicle according to the vehicle conditions for the following purposes.

When capacitor (i-ELOOP) relay is disconnected	Outline
Ignition is switched off	•  To prevent a short to the 24.3 V related power or to reduce back-up current during servicing, the capacitor (i-ELOOP) relay is disconnected approx. 30 s after the ignition is switched OFF. Note •  By switching off (open) the bypass relay in the DC-DC converter (i-ELOOP) at the same time the capacitor (i-ELOOP) relay is disconnected, the power supply is put in a condition in which it cannot be supplied to the vehicle from the capacitor (i-ELOOP).
During collision	•  The capacitor (i-ELOOP) relay is disconnected to assure safety in a vehicle collision. Note •  The DC-DC converter (i-ELOOP) detects a collision signal from the SAS control module and sends a generator output stop request signal to the PCM. In addition, power cannot be supplied to the vehicle from the capacitor (i-ELOOP) by stopping the voltage reduction circuit in the DC-DC converter (i-ELOOP) and turning the bypass relay off (open) at the same time the capacitor (i-ELOOP) replay is disconnected. •  This condition can be cancelled by switching the ignition OFF.
In pre-charge mode for i-ELOOP operation	•  The capacitor (i-ELOOP) relay is disconnected to assure excitation current to the generator when power from the battery is used (in pre-charge mode for i-ELOOP operation).
In fail-safe	•  The capacitor (i-ELOOP) relay is disconnected while in fail-safe.

•  For details on the capacitor (i-ELOOP) relay operation, refer to the [i-ELOOP]. (See i-ELOOP [i-ELOOP].)

Fail-safe

DC-DC converter (i-ELOOP)

PCM