Thirty-six papers reached the technical panel at the Directorate General of Mines Safety in Dhanbad. Fourteen were selected for publication. Ours was one of them.
The paper is based on “Design, Safety and Deployment Experience of a Liquid-Cooled LFP Battery System for Underground Mining Applications”, by Pushkin Gautam, Bablu Yadav and Mainak Bhanja of CLN Energy Limited page 119. It appears on pages 119 to 125 of the souvenir released at Batteries for Mining Sector — Challenges and the Way Forward (BMS-2026), the national seminar organised by DGMS with Mahanadi Coalfields Limited and held at the DGMS headquarters auditorium in Dhanbad on 10 August 2026.
We did not write it from a literature review. We wrote it from practical experience: a 537.6 V, 230 Ah, 123 kWh liquid-cooled LFP battery pack our team designed and built for an underground passenger shuttle vehicle page 119. Every argument in it came out of that build.
Download the paper (PDF, 7 pages) — or click any page reference in this article to open it at that page.
A mining battery is not only a bigger EV battery. Packs for underground mining have to work through elevated ambient temperatures, high humidity, coal dust, continuous mechanical vibration, water ingress and confined operating space page 119 — conditions a road vehicle never sees.
A road vehicle also cools itself for free: air moves across it as it drives. A machine working underground gets none of that. It runs slowly, in a confined space, in air that is already warm, and the heat its cells produce has nowhere to go on its own. Cooling therefore has to be engineered in deliberately — which is why this pack is liquid cooled, and why the cooling system was designed before the enclosure around it was fixed.
The design target was simple to state and hard to meet: hold every cell at 25 ± 3 °C while the mine around it sits at up to 45 °C page 124, for a full shift, on a machine subject to severe vibration in underground haul page 121.
| Parameter | Specification |
|---|---|
| Cell chemistry | Lithium iron phosphate, prismatic page 121 |
| Configuration | 168S 1P page 121 |
| Nominal | 537.6 V · 230 Ah · 123 kWh page 121 |
| Voltage range | 470.4 V – 604 V page 121 |
| Discharge | 230 A continuous · 400 A peak for 30 s page 121 |
| Charge | 55 A continuous · 115 A maximum pages 121-122 |
| Depth of discharge | 90% page 122 |
| Fast charging | 60 kW DC, CCS2 interface pages 125, 119 |
| Structure | Four cell modules plus a dedicated PDU, single enclosure page 119 |
Cooling. Each prismatic cell is thermally coupled to the cooling system through a high thermally conductive gap filler. No two surfaces meet perfectly: manufacturing tolerances and small surface irregularities leave thin air gaps between the cell casing and the cold plate, and air is a poor conductor of heat. The pad fills those gaps, so heat passes from the cell into the plate instead of stalling at the joint. The cooling assembly is stacked aluminium cold plates with macro-channel flow passages — aluminium chosen for thermal conductivity, low density, corrosion resistance and extrudability. The chiller is a single integrated unit: 5 kW cooling capacity, COP ≥ 2.5, R134a refrigerant, 50:50 water-glycol coolant, 400–800 V dc, communicating over CAN 2.0 page 124.
Does it work? CFD simulation in ANSYS Fluent — modelling cell heat generation, coolant flow, pack geometry and operating conditions representative of underground coal mining — predicted a maximum cell temperature below 30 °C and a minimum of about 25 °C, a variation of 3 °C across the whole pack page 124.
That number is the result worth dwelling on. A 3 °C spread means cells age at close to the same rate as each other, and a pack that ages evenly is one that stays predictable after years of hard cycling.
Enclosure. IS 513 CR1 cold-rolled steel, selected for structural strength, manufacturability and cost page 123, IP67 sealed page 125. It is mounted on dedicated structural brackets with anti-vibration elastomeric isolation pads of Neoprene sheet, which attenuate the high-frequency vibration and impact loads coming off the vehicle chassis. Pressure relief vents manage abnormal internal pressure rise from a cell venting event page 123.
Electrical protection. A dual-contactor configuration with a pre-charge circuit to limit inrush at startup; main positive and negative contactors rated 500 A; a Manual Service Disconnect rated 630 A; a High Voltage Interlock Loop and an Insulation Monitoring Device page 123.
The BMS is developed exclusively in India page 123. It monitors individual cell voltages, pack voltage and pack current, and temperature across 16 module sensors and 5 PCB sensors, with SOC estimation, fault diagnosis, CAN communication to the vehicle controller and an insulation monitoring interface. When a predefined threshold is exceeded it opens the main contactors and electrically isolates the battery — covering cell over-voltage, cell under-voltage, pack over-current, over-temperature, under-temperature, insulation faults and HVIL interruption page 123.
The safety architecture is deliberately layered: intrinsically stable LFP chemistry, active liquid cooling, dual contactors with pre-charge, the 630 A MSD, HVIL, IMD, pressure relief vent, emergency disconnect, IP67 enclosure, continuous cell temperature monitoring and real-time fault detection through the BMS page 125. Mechanical, electrical, thermal and electronic protections that do not depend on each other to work.
High energy density is not the first thing to optimise for a machine that returns to a charging bay at the end of every shift.
Lead-acid batteries have been used underground for decades, and for sound reasons: they are inexpensive, the manufacturing is mature, and every workshop already knows how to look after them. What they cannot do is support a modern battery-electric machine. At 30–50 Wh/kg they carry little energy for their weight, they charge slowly, they last relatively few cycles, and they need regular attention page 120.
Among lithium-ion chemistries, LFP is the preferred choice for underground mining equipment because of its thermal stability, superior abuse tolerance, extended cycle life and comparatively lower risk of thermal runaway page 120. The paper sets a comparison with lead-acid, LFP, NMC, sodium-ion, LTO and solid-state against energy density, cycle life, thermal stability, charging speed and maintenance page 121 — and on the parameters that decide a mining application, LFP wins on the ones that matter and gives up ground only on the one that matters least here.
Design the cooling before the enclosure is fixed. How much heat the pack has to move, how the cells are spaced and where the coolant runs all have to be settled before the enclosure design is frozen. On this pack, cell temperature uniformity through active liquid cooling was a design objective from the start rather than something added afterwards page 121.
Choose chemistry against the mine, not the spec sheet. The question is not which cell stores the most energy, but how it behaves when something goes wrong in a confined space.
Design for service in a roadway, not a workshop. The modular arrangement — four modules and a separate PDU — was chosen specifically to simplify manufacturing, transportation, inspection and maintenance, and to leave flexibility for future servicing page 120.
Treat charging infrastructure as part of the safety case. High-power DC charging introduces additional thermal and electrical stress that has to be managed by coordinated control between charger and BMS. Underground charging stations should incorporate insulation monitoring, emergency shutdown, over-current protection, earth fault detection and appropriate ventilation where required page 125.
The pack was specified to hold cell temperature within 25 ± 3 °C during normal operation despite ambient temperatures reaching 45 °C. That requirement is what drove the active liquid-cooling system page 124.
LFP offers excellent thermal stability, superior abuse tolerance, extended cycle life and a comparatively lower risk of thermal runaway, which is why it has become the preferred choice for underground mining equipment page 120.
After several design iterations, the cold plates were finalised and the coolant flow set according to the CFD simulation results. The simulation predicts a maximum variation of 3 °C across the pack page 124.
The pack is not bolted rigidly to the machine. Its IS 513 CR1 cold-rolled steel enclosure sits on dedicated structural brackets, with Neoprene elastomeric pads between the two. Those pads absorb the high-frequency vibration and shock loading a mine haul route puts into the chassis, so far less of it reaches the cells page 123.
Yes — 60 kW DC fast charging through a CCS2 interface, designed to allow recharge during planned operational intervals pages 125, 119.
The BMS opens the main contactors and electrically isolates the battery. It supervises cell over-voltage, cell under-voltage, pack over-current, over-temperature, under-temperature, insulation faults and HVIL interruption page 123.
The 123 kWh pack is the best product our engineering team has built so far, and it was built by the team rather than by any one person. The paper is authored by Pushkin Gautam, Bablu Yadav and Mainak Bhanja, and credit is due to the management for backing a project that had no comparable reference in the Indian market when it started.
What made the seminar worth attending was what happened after the session. The questions came from senior mining equipment manufacturers and from DGMS itself, and they were the specific kind — thermal limits, approval routes, what happens to a pack after years underground. That is the conversation the sector needs to be having.
The full paper runs from page 119 to page 125 of the BMS-2026 souvenir. If you are building or specifying battery-powered equipment for Indian mines, write to us and we will share what we learned.
Pushkin Gautam, Bablu Yadav and Mainak Bhanja (2026). “Design, Safety and Deployment Experience of a Liquid-Cooled LFP Battery System for Underground Mining Applications.” In: Souvenir — National Seminar on Batteries for Mining Sector: Challenges and the Way Forward (BMS-2026), pp. 119–125. Directorate General of Mines Safety, Dhanbad, in association with Mahanadi Coalfields Limited. 10 August 2026.
Download the paper (PDF, 7 pages, 1.6 MB)
Become a
Partner
Comments: