FACTOR-e Battery

The FACTOR-e battery is available in two nominal capacities: 1.8 kWh and 2.5 kWh.  Their exact specifications are:

• 50.4V / 34.9 Ah / 1758 Wh

• 50.4V / 50 Ah / 2520 Wh

The 1.8 kWh battery (part number TC03R-50200-00-01) retails for $5,821.88 in the USA.  As of September 2025, the item is not stocked.  It is said to be imported and shipped within 3 to 4 weeks.

Apparently, the 2.5 kWh battery (part number TC03R-50200-00-00) is not presently available as a spare part at all in the US.  Its part number redirects to the 1.8 kWh battery.

For reference, the 2620 Wh Escape battery retails for nearly $7000. 

A look Inside the 2.5 kWh Battery

Samsung INR21700-50S

These 21700-size cells are listed as high-discharge and are rated for 5000 mAh.  As of September 2025, they can be purchased in small quantities for $6.50 (USD) each.  So there is considerably less than $1000 worth of cells in the 2.5 kWh battery.

Samsung gives the following specifications: 

• Nominal Capacity: 5000 mAh

• Nominal Voltage: 3.6V (using 14 series cells gives the nominal 50.4V pack voltage)

• Discharge End Voltage: 2.5V

• Charging Current: 2.5A

• Max Charging Current: 4.9A

• Max Continuous Discharging Current: 25A (45A with 80C temperature cutoff)

• Dimensions: 70.62 mm (long) x 21.25 mm (diameter)

• Weight (max): 72.0g

A bit of arithmetic tells us that one hundred forty 72-gram cells equals 10.08 kg.  By comparison, the Epure Race battery uses older technology in its 1.78 kWh battery.  It contains one hundred sixty-eight 45.5-gram cells for a total cell weight of 7.65 kg.  Thus, the FACTOR-e battery yields 1.38x more energy but with only 1.3x more cell weight. 

Noteworthy Components

Discharge Relay: Manufactured by Hongfa.  Part number HFV19-100  48-HL-SLT

Charge Relay: Manufactured by Potter & Brumfield.  Part number T9AS1D22-48

Current Transducer: Manufactured by LEM Sensors.  Part number HASS 200S.  This is the same device used in the Epure Race.  It's nominally rated for +/-200 amps, but can make measurements as high as +/- 600 amps.

Main Fuse:  Manufactured by Buss.  Part number AMXL.  Rated for 300 Amps.  Moving the main fuse inside the battery is probably a good idea since it gets it out of the way.  The fuse is there to protect against a fire in the high-current wiring.  The likelihood of it blowing is very small, and therefore not making it user serviceable is not really a loss.  This is a high-quality fuse that sells for about $6 in 100-piece quantities. 

Two large diodes: (D2 and D3 in TO247 packages) They appear to be marked “60CPQ150” which is a 30A, 150V Schottky diode.  Possible being used for reverse-polarity protection for the charger?

PCB: A custom printed circuit board marked “EM TOP-PCB v 1.4” can be seen under the BMS.  This is a huge improvement over wire interconnects, providing better reliability and reduced assembly cost.

Battery Management System

Like my Epure Race battery, the FACTOR-e BMS was made by ION Energy in India.  In fact, the two BMSs appear to be very similar.

At first, I thought the microcontroller (big black 100-pin chip) seemed like overkill for this job. However, there is no dedicated battery-management IC.  So it would seem the microcontroller is taking on that task.  This makes sense as a cost reduction measure for the BMS manufacturer.  However, there is an increased cost for firmware development with this method.  Anticipated production volumes must take this into account.

The microcontroller is manufactured by Microchip Technology.  It is their part number dsPIC33EP512GM710-E/PT, which costs about $8 in 119-piece quantities.  Some of the microcontroller's specifications are highlighted below:

• Speed: 60 MIPS (million instructions per second)

• Core: 16-bit

• Program memory: 512 KB flash

• RAM: 48 KB

• I/O lines: 85 total

• Analog-to-digital converter: 48 channel, 10 and 12-bit resolution, max sampling rate of 1100 ksps 

• CANbus support: Yes

• Temperature grade: Automotive (-40 to +125 C)

Descriptions of Annotated Area

Piezoelectric Buzzer: (black cylinder on ancillary PCB, near main fuse.)  Ostensibly, it's for annunciation, but actually hearing it inside the sealed enclosure seems unlikely to me.

uC: Microcontroller described earlier.

16 MHz: Apparently it's possible for the microcontroller to be self-clocked, but there is a 16 MHz crystal adjacent to it.

SMPS: A Switch-Mode Power Supply is used to buck the battery voltage down to about 3.3 VDC to run the microcontroller and other circuitry on the BMS.

LEDs: Likely for reporting status.  At least one of these LEDs flashes constantly (even with the battery OFF). 

Config Switches: These probably tell the number of series cells to be monitored.

Main Fuse: Described earlier.

Balance FETs: (Field-Effect Transistor) Each group of series-connected cells requires a switch to discharge it during balancing.

Cell Wires: Each cell in the series requires two microcontroller I/O pins, one to measure analog voltage and one to turn the charge balancing FET on/off.  

Thermistor Wires: A number of temperature sensors are needed to assure safe charging and discharging.   

SD Card: Since even a small SD card can hold gigabytes of data, there is the potential to store a lot of information on the battery's state of health.  My understanding is that it's possible to communicate with the battery (wirelessly?) via a dealer-level tool.  This information should be made available to the end user.

I assume there are some surface-mount resistors on the underside of the BMS to dissipate energy during charge balancing.  Charge balancing must be of the passive type, since I don't see any circuity that would be used for active charge balancing. 

What about the 1.8 kWh battery?

What can we surmise about the 1.8 kWh battery?  Based on actual capacity numbers, it's possible to calculate some ratios. 

1758 Wh / 2520 Wh = 0.697

We know the 2.5 kWh battery uses 10 parallel groups of cells. 

But 10 × 0.697 = 6.97.  This is obviously not an integer.  Maybe the small battery uses 7 parallel groups of INR21700-50S cells, but I think it's more likely to be using a different cell altogether.

The number of parallel cell groups dictates the battery's capacity (and therefore vehicle range).  But just as important, it dictates the maximum allowable current draw (which sets a limit on the peak motor current).