Based on nothing more than a WAG, run both sides direct from the battery. It shouldn't matter but it's safer to never know .

 

 

You can play Guinea Pig, you know "take one for the team"! Let us know if run into problems.

 

My trailer winch has its own battery.

 

The factory ground wire will probably burn up, it is to small to carry the load a winch will pull.

 

Your starter motor, among many other things, gets its ground thru the engine block to the frame and back to the battery. The winch shouldn't be a problem.

 

You need to look again. the battery ground goes directly to the engine block, Then a small flat flex strap goes to the body and then to the frame. I have personally seen the strap burn up as my ex boss did the same exact thing trying to run a wench on a trailer with the vehicle battery.

 

By all means, if possible use a second separate battery.

If you are going to use the truck battery, a separate negative and positive wire directly to the truck battery should be used. You never know what king of voltage spikes will occur, and having those spikes travel along the truck wiring & chassis ground (negative) is not good.

If you wanna OCD on grounding, google: "integrated & isolated ground plains".

Have fun.

 

It is SO much more complicated than you think. If you have either EcoBoost engines, your truck has an energy monitoring system That I can't even begin to describe but I'll let Ford explain it to you.
Some things to note are the part about never connecting directly to the negative battery post and the fact that you need a scan tool to reprogram the system if you buy a new battery - you can't just go to Walmart and drop in a new battery.

Also the negative post of the battery IS connected to the frame.

A little bit of light reading....

Charging System The PCM controlled Smart Charge charging system determines the optimal voltage setpoint for the charging system and communicates this information to the voltage regulator. The Smart Charge charging system sets Diagnostic Trouble Codes (DTCs) when a charging system fault is present. All of the Diagnostic Trouble Codes (DTCs) can set continuous faults, but not all Diagnostic Trouble Codes (DTCs) set as on-demand faults.This system uses 2 communication lines between the PCM and the generator/voltage regulator: A generator communication (GENCMD) line communicates the desired setpoint from the PCM to the voltage regulator, and a generator monitor (GENMON) line communicates the generator load and error conditions to the PCM . Both of these use PWM . The PCM sends the GENCMD command only when it is necessary to adjust the voltage setpoint. If the setpoint does not need to be changed, several seconds may elapse between PCM GENCMD commands. This normal operation appears in the PID as occasional bursts of pulse-width commands. In addition to these two circuits, a third pin on the voltage regulator, the "A" circuit pin, is dedicated to monitor, or sense, the battery voltage.The PCM simultaneously controls and monitors the generator output. When the current consumption is high or the battery is discharged, the PCM raises engine speed as needed to increase generator output. The generator charges the battery and at the same time supplies power for all of the electrical loads. The battery is more effectively charged with a higher voltage when the battery is cold and a lower voltage when the battery is warm.The PCM turns off the generator during cranking to reduce the generator load and improve cranking speed. Once the engine starts, the PCM slowly increases generator output to the desired voltage.The PCM reports any charging system faults and sends a message through the HS-CAN1 to the BCM . The BCM controls the charging system warning indicator by sending a message through the GWM to the IPC . The status of the PCM charging system warning indicator and/or message is confirmed by viewing PCM PID generator fault indicator lamp (GENFIL). Any charging system fault detected by the PCM results in 1 or more Diagnostic Trouble Codes (DTCs) being set and the PID GENFIL having a status of On. If equipped with a charging system warning indicator, the IPC turns the indicator on or off. If equipped with a message center, the IPC displays a CHECK CHARGING SYSTEM message. In some instances, the CHECK CHARGING SYSTEM message may not display if the ignition is on and the engine is off.Under certain circumstances, the charging system may have a concern but will still keep the battery charged and the vehicle running. GENCMD normally initiates charging but with a fault in this circuit, the generator can self-excite and start charging on its own. The charging system warning indicator is illuminated and/or the CHECK CHARGING SYSTEM message is displayed, and the generator operates in a default mode (approximately 13.5 volts).

Electrical Energy Management System NOTICE: When any vehicle module is being programmed, connect an external battery charger to make sure the module programming is completed without interruption due to the load shedding feature becoming active. The external battery charger must maintain a system voltage above 13 volts. This may require a charger setting higher than the lowest charge setting. The external battery charger negative connection must be made to an engine or vehicle chassis ground and not the negative battery terminal. If the connection is to the negative battery terminal, load shedding may begin and module programming may be corrupted. After charging has begun, start the engine to clear any load shed states and then turn the engine off and proceed with programming. This vehicle is equipped with an Electrical Energy Management system which manages battery charging and monitors the battery state of charge. The Electrical Energy Management system software is housed in the BCM . It has the algorithms and control structure for the Smart Regenerative Charging, and Load Shed Control Strategy. The Electrical Energy Management system is equipped with a battery monitoring sensor and generator current sensor to monitor the battery. These sensors serve as input to the Electrical Energy Management system software. If the sensors malfunction due to wiring issues or failure, a DTC will be set. In most cases the Electrical Energy Management system functions will be turned off until the sensor operation is restored. Battery State of Charge The Electrical Energy Management system monitors the battery current flow and voltage to determine the battery state of charge. During the drive cycle the Electrical Energy Management system software monitors the charge and discharge current and increases the state of charge during charging, and decreasing it during discharge. During rest periods (key off with no electrical loads) when the vehicle enters sleep mode, the battery voltage is sampled to calibrate the state of charge. The battery monitoring sensor automatically executes a calibration anytime the vehicle enters sleep mode and the total vehicle current draw is below 300mA. It takes 8 hours in the sleep mode to calibrate the battery state of charge to high accuracy. If the system draw has not allowed the battery state of charge to calibrate over the previous 7 days, the state of charge quality factor changes to identify this and some Electrical Energy Management system functions may be temporarily turned off until a calibration takes place.NOTE: Any devices left attached to the power socket that draw more than 200mA (or less depending on other battery loads), prevents the battery monitoring sensor from calibrating the battery state of charge. Engine Off Load Shed The BCM uses the battery monitoring sensor to keep track of the battery state of charge. When the engine is off and the BCM determines the battery state of charge is below 50%, or 45 minutes have elapsed, a load shed message is sent over the CAN . This message turns off the audio/navigation system to save the remaining battery charge. Under this condition the FCDIM (without touchscreen controls) displays System Off to Save Battery Turn Ignition Off, or the FDIM (with touchscreen controls) displays SYSTEM OFF TO SAVE BATTERY PLEASE TURN IGNITION OFF OR START ENGINE to notify the driver that battery protection actions are active.Engine off load shedding occurs when the engine is not running and the ignition is in the ACC, RUN or delayed accessory position. This load shed state clears once the vehicle has been started and the battery state of charge recovers. If the engine off load shed occurs, the audio/navigation system turns off.When the ignition is in the RUN position and load shed occurs, the IPC message center may display either TURN POWER OFF TO SAVE BATT (base message center) or TURN POWER OFF TO SAVE BATTERY (optional message center). The audio/navigation system shuts down after the message center displays the warning.If a fault occurs with the battery monitoring sensor or circuit(s), the only engine off load shed strategy that is active is a 45 minute timer. After 45 minutes have elapsed, the audio/navigation system turns off. To clear the load shed state, restart the engine.When the ignition is in the OFF position or the ignition key is removed, the infotainment extended play feature can be enabled. When infotainment extended play is enabled and a load shed message is received over the CAN extended play will turn off to save the remaining battery charge. Under this condition FCDIM displays SYSTEM OFF TO SAVE BATTERY to notify the driver that battery protection are active. For more information,
Refer to: Message Center - System Operation and Component Description (413-01 Instrumentation, Message Center and Warning Chimes, Description and Operation). Engine Running Load Shed When the BCM and/or PCM senses voltage is low, with the engine running, the BCM sends a message to either minimize or shut down the climate controlled seats, rear defrost, heated mirrors and climate control blower motor to improve system voltage. Under this condition, the IPC message center displays LOW BATTERY FEATURES TEMPORARILY TURNED OFF to notify the driver that battery protection actions are active during a Load Shed 2 continuous event.For more information on message center messages, Refer to the Owner's Literature or
Refer to: Message Center - System Operation and Component Description (413-01 Instrumentation, Message Center and Warning Chimes, Description and Operation). There are 3 states of engine running load shed: Load Shed StateEntry ConditionsImpact to FeaturesClear ConditionsLoad shed 1Alternator at full load and battery discharging while driving. System voltage less than 11.5 voltsThese loads are incrementally reduced (if equipped): Heated steering wheel and climate controlled seats. These loads are turned off (if equipped): smart trailer tow battery charge, heated mirrors, heated backglass, and heated windshield.System operating at normal power level.Load shed 2 transientEPAS indicating reduced voltage and increased current. System voltage less than 11 voltsThese loads are turned off without customer indication (if equipped): Heated steering wheel, smart trailer tow battery charge, climate controlled seats, heated mirrors, heated backglass, and heated windshield.System operating at normal power level.Load shed 2 continuousLoad Shed 2 Transient condition in excess of 20 secondsIn addition to Load Shed 2 Transient, these loads are turned off (if equipped): 110-volt inverter, heated windshield, and climate control blower (reduced speed less FMVSS required operation). During Load Shed 2 the Continuous feature on indication will turn off for these loads: heated steering wheel, climate controlled seats, heated mirrors, and heated backglass.System operating at normal power level.

Battery Charging When it is necessary to charge the vehicle battery it is important to properly connect the charger for the Electrical Energy Management system to measure the energy input to the system to keep an accurate state of charge. Connect the charger positive cable to the battery positive post, and place the charger negative cable to a vehicle ground. Do not connect the charger negative cable to the battery negative terminal. Connecting the charger directly to the battery negative post bypasses the vehicle sensors, preventing the battery monitoring sensor from detecting the charge current. As a result the battery state of charge does not reflect the charging. For a good connection point, follow the negative cable from the battery monitoring sensor to the vehicle body connection (typically on the shock tower sheet metal). The placement of the battery is such that the battery negative terminal is located under the sheet metal shroud making sheet metal ground the obvious choice for the charger.If the battery is being charged due to a load shedding message, only properly charging the battery assists in clearing this message. If the charger was improperly installed, the Electrical Energy Management system calibrates the battery state of charge after about 8 hours.NOTICE: If the charger is incorrectly connected to the battery negative terminal, DO NOT reset the battery monitoring system using the diagnostic scan tool. This reset is reserved only for new battery installation. This reset will clear the learned battery data, the battery time in service, and will affect the aging algorithm parameters, which have been learned since the installation of the battery. Jump Starting When it is necessary to jump start the vehicle it is important to properly connect the cables for the Electrical Energy Management system to measure the energy input to the system to keep an accurate state of charge. Connect the positive cable to the battery positive post and the jump start negative cable to a vehicle ground. Do not connect to the negative battery terminal. Connecting directly to the battery negative post bypasses the ability of the vehicle to measure the input current with the battery monitoring sensor, and does not adjust the battery state of charge accordingly. For a good connection point, follow the negative cable from the battery monitoring sensor to the vehicle body connection (typically on the shock tower sheet metal). If the vehicle was improperly jump started, the Electrical Energy Management system calibrates the battery state of charge after about 8 hours.NOTICE: If the cables are incorrectly connected to the battery negative terminal, DO NOT reset the battery monitoring system using the scan tool. This reset is reserved only for new battery installation. This reset will clear the learned battery data, the battery time in service, and will affect the aging algorithm parameters, which have been learned since the installation of the battery.

Battery Replacement If the vehicle battery is replaced, it is very important to perform the battery monitoring system reset using the diagnostic scan tool. If the battery monitoring system reset is not carried out, it holds the old battery parameters and time in service counter in memory. Additionally it tells the system the battery is in an aged state and may limit the Electrical Energy Management system functions. For more information,
Refer to: Battery and Cables - System Operation and Component Description (414-01 Battery, Mounting and Cables, Description and Operation). Component Description

Generator The generator is equipped with an electronic internal voltage regulator and a serviceable generator clutch pulley. Generator Current Sensor The generator current sensor is attached to the generator B+ cable. It is supplied a 5-volt reference voltage and a ground from the PCM . The generator current sensor is a Hall-effect sensor that supplies an analog feedback signal to the PCM . The PCM uses this information for battery charging strategy and idle stability and torque control. Battery Monitoring Sensor The battery monitoring sensor is integrated with the negative battery terminal clamp and cable assembly, which provides a ground to the sensor. The battery monitoring sensor measures voltage, current, and temperature of the battery and uses these inputs to calculate the battery condition. The sensor transmits this information through a LIN circuit to the BCM . The battery monitoring sensor has a 2-pin connector providing battery voltage and LIN connections. Powertrain Control Module (PCM)

The PCM monitors and controls the charging system.

Generator Clutch The primary function of the generator clutch is to separate the generator rotor inertia from the FEAD belt, lowering belt tension at high Revolutions Per Minute (RPM) and reducing NVH . The generator clutch is serviced separately from the generator.

Bottom Line: Don't connect to the Negative Battery Post.

 

All of this because of the AGM batterie?

 

I think its a conspiracy to make you go back to the dealer for a new battery. If you don't have the scan tool the system will continue to treat the new battery as if it was the old worn out battery.

 

 

You won't. The system just thinks that you still have the old battery and will manage its charging / discharging performance as such.