Charging of the battery requires that the specified voltage be determined. The specified voltage is the voltage that must be present at the terminals of the battery in an optimal manner.

Depending on various factors, the specified voltage is determined using the alternator management or using the temperature-dependent charging characteristic including the fast charge function.

After the engine is started, immediate charging is performed first at high battery is recognized as being sufficient.

NOTE:

Immediate charging is done at least 20 seconds or more. Beside, the fast charging is not finished until the vehicle speed is more than 4 km/h (2.5 MPH). After this, a Switch is made to a temperature-specific charging characteristic or alternator management.

Alternator management includes lowering of the charging voltage is approximately 12 V and a regenerative braking (energy recovery) option when the engine is in deceleration mode.

A safety cutout is activated when driving down long hills in order to avoid overcharging of the battery resulting from long periods of deceleration fuel shutoff. This protective cutout deactivates regenerative braking (energy recovery) in cases of high voltage combined with low power consumption.

When the battery becomes fully charged (for example after driving in the cold or long downhill travel), the voltage is lowered further to return the battery to its optimum charge level.

Various Phases of Voltage Provision

Courtesy of NISSAN NORTH AMERICA, INC.

A:	Engine start	B:	Fast charging	C:	Temperature-based charging
D:	Alternator management	U:	Voltage	T:	Time

Function	Outline
Fast Charging	Voltage up to 13.5 - 14.7 V Once after engine starting Optimized charging of battery (including during short trips) Duration time: 20 seconds or more. Fast charging ends when charge of battery is sufficient No fast charging with trailer operation No fast charging when the battery is too warm Not finished until vehicle speed is more than 4 km/h (2.5 MPH)
Transition To Alternator Management	Fast charging ended Battery temperature: more than 2°C (36°F) Ambient temperature: more than 2°C (36°F) Charge level of the battery is sufficient. No trailer operation
Temperature-Based Charging	Fast charging ended, alternator management not possible Voltage range: between 13.5 V and 14.7 V Linear charging characteristic
Alternator Management	Battery voltage is: Approx. 12 - 13 V (According to charge level of battery) Approx. 13.0 - 13.7 V (for some light functions ON) Approx. 13.8 V (With wiper ON) Approx. 13.5 -14.7 V (Re generative condition)

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Charge Battery Function Sequence

Use the Manual With the Right Hardware

When to See a Mechanic

Rather have a pro handle this?