The traction battery charging system on your NiMH Ranger EV is an automated system to manage charging of the 25 NiMH Modules. While the system is designed to operate unattended, A New Generation Star (NGS) tester with a Ranger EV Program card is highly recommended for manual monitoring of this sophisticated system.

Unfortunately, without a NGS tester, you will be totally in the dark as far as what is happening when your Ranger EV is connected to the PCS. While you’ll notice changes in the dash mounted fuel gauge and Distance to Empty gauge, you’ll have no idea where you are the charging process.

Note: a NGS tester with Ranger EV Program card is highly recommended. The following discussion is based on observing the parameters only available from a NGS tester.

When the PCS is connected to my Ranger EV, the BCM senses the presence of the AVCON connector and sends a signal back to the PCS to close the contactor that connects the 220v AC power to the On-board Charger. The BCM Operating state changes from BCM_OP2 Idle, to BCM_OP5 Current Mode and the Traction Battery charging process begins. The charging current will ramp up to approximately 14amps and the voltage will begin to increase. You’ll hear various fans, relays, cooling pump begin to switch on and off as controlled by the BCM that is orchestrating the charging process. Depending on how far the traction battery has been discharged, the BCM_OP5 Current mode will continue for about 6 hours until Traction Battery State of Charge BAT_SOC reaches 99.99% and the BCM senses the need for BCM_OP6 Voltage mode. The BCM_OP6 is followed eventually by BCM_OP87 Full Charge, or an alternative premature termination of the charging process. While BCM_OP 87 is designated Full Charge, the charging process isn’t complete until the pack has been cooled back down. This can take several hours depending on ambient conditions. I leave my truck connected to the PCS until the pack is below 30C preferably.

1. NiMH – The traction battery pack is located in a large coffin enclosure under the truck between the frame rails and extending from just in front of the rear axle to just behind the front mounted radiator. There are 25 12v NiMH modules for a total of 300v DC. Warning!: 300v DC is a LETHAL voltage and should be treated with TOTAL respect. If you ignore this warning, your heirs will have the grim task of selling your Ranger EV.
   

2. PCS – The Power Control Station is usually wall or post mounted and is connected to a 220v 40/30amp single phase AC power source. A heavy cable with an induction AVCON connector that plugs into a receptacle mounted behind a small door in the grill of your Ranger EV carries both the AC power circuit as well as a control circuit that allows the Ranger EV to know the PCS is connected and then send a signal to the PCS to energize a contactor relay to energize the AC circuit.
   

3. On-board Charger – The On-board Charger is mounted under the hood of your Ranger EV in the center near the top generally where you would expect to find the air cleaner on a conventional ICE Ranger with a carburetor. The On-board charger converts the 220v AC to DC voltage to recharge the NiMH traction batteries. The On-board Charger is air cooled with a built-in fan in the base. This fan operates automatically so be careful about searching around for it with your fingers. Beware that the On-board charger will get VERY hot during normal operation.
   

4. BCM – The Battery Control Module monitors the 25 NiMH modules and controls various components including the On-board Charger to supply the necessary current and voltage to these modules and is located along with the NiMH batteries in the battery pack enclosure.
   

5. DC/DC Converter – The DC/DC converter down converts the 300v DC output from the traction battery pack to 12v DC to operate many of the auxiliary systems like lights and horn, and recharges the 12v auxiliary battery. There is no alternator or generator in your Ranger EV, so this auxiliary battery is only charged during the traction battery recharging process or when the ignition key is in the on position. The DC/DC converter is located under the hood and just to the left of the On-board Charger.
   

6. Cooling System – The Ranger EV utilizes a water based cooling system with 12v DC water pump, Ford Explorer radiator with a system of hoses and tubes to supply cooling fluid to various heat producing components including the DC/DC Converter as well as the AC Inverter, TIM, and Traction Motor.
   

7. Cooling Fans – The NiMH Ranger EV has two cooling fans in the Battery Enclosure to circulate the air inside the enclosure and to draw cool outside air and expel the hotter air inside the enclosure.

Monitor – If I charge during the daytime, I always monitor the charging process with the NGS tester connected. I monitor:

1. Aux_CNT - Auxilary Current
   

2. AVGTEMP – Average Temperature
   

3. BAT_SOC – Battery Pack State of Charge
   

4. BCM_OP – BCM ECU Operating State
   

5. TMPSENS1
   

6. TMPSENS2
   

7. TMPSENS3
   

8. TMPSENS4
   

The Battery Pack State of Charge lets me see how the charge is progressing toward 100% (actually 99.99%), the BCM-OP tells me which portion of the charging algorithm the truck is at, and the temperatures tell me if things are getting too hot.

Time of Day – I live in sunny Southern California and try to only charge at night. Since I don’t drive my truck every day, I only need to charge a few times per month. I find the traction battery generates the most heat during the last portion of discharge and the last portion of recharge. If the pack gets too hot and the ambient temperature isn’t cool enough, I can’t get the pack to cool down because there’s not enough temperature differential between the pack and the incoming ambient air. Ford did not recommend using Ranger EVs in warm climates like Arizona. If the pack state of charge is down to about 20%, I’ll start charging around 4PM and the OP5 Current Charge will end around midnight and the OP6 Voltage charge hopefully shortly thereafter and reach an OP87 ‘Full Charge’. The pack temperatures should be peaking about this time and the nighttime ambient temperatures will be getting much cooler than during the warm daytime. This allows optimal pack cooling for the rest of the night. The cooler the pack gets, the cooler the ambient temperature gets until the pack has completely cooled around daybreak. During the night, the BCM has switched back and forth between OP87 and OP6, but the pack will stay as cool as possible and hopefully never exceeded 45C and be below 30C when I check it in the morning. This minimizes the duration of peak temperatures in the pack and extends the life of my critical NiMH batteries.