The SAGMOTO i9 electric medium and heavy duty truck carries a lithium iron phosphate pack sized between 350 and 450 kWh to deliver a 250 to 300 km working range under the 245 to 410 kW peak output of its permanent magnet motors. At this energy density the pack is only as durable as its thermal management, because cell temperature swinging beyond the 15 to 35 degrees Celsius comfort band accelerates capacity fade and triggers charge throttling. The i9 uses a liquid cooling plate architecture with a dedicated low-temperature coolant loop separate from the cabin circuit, controlled by a battery management system that modulates two electric pumps, a plate chiller and a positive-temperature-coefficient heater. Shaanxi Fenghan Trading exports the i9 to distributors building depot-based fleets in Europe, the Gulf and increasingly Latin America, where ambient extremes make the thermal loop the most service-sensitive subsystem on the vehicle.
i9 Coolant Loop Architecture
The i9 thermal system splits into two independent loops. Loop A is the battery plate loop, filled with a 50 percent water and 50 percent ethylene-glycol mix carrying corrosion inhibitors rated for aluminium cold plates; it holds 9.5 litres and circulates only through the pack, the chiller and the plate heat exchanger. Loop B is the cabin and power-electronics loop at a different colour dye and is never cross-filled with Loop A. The battery loop runs through a series of stamped aluminium cooling plates bonded under each module, with parallel flow so a single blocked plate does not starve the row. A degas bottle on the inner wing maintains a 0.5 bar static head and lets air rise out during fill. The two loops share a physical neighbourhood but never share fluid, and mixing them is the fastest way to foul the chiller core.
Loop A and Loop B use different coloured caps for a reason. The battery glycol is a low-conductivity inhibited mix; the cabin loop is standard vehicle glycol. Topping the battery loop from the wrong drum silently raises conductivity and the battery management system will flag an insulation fault that strands the truck with no drive.
Electric Coolant Pump Operation
Two brushless DC pumps move Loop A, a primary rated at 45 litres per minute and a secondary rated at 30 litres per minute that the controller brings online above 60 percent state-of-charge draw or during fast charge. Pump speed tracks pack inlet temperature: below 25 degrees the primary runs at 40 percent, between 25 and 32 degrees it climbs to 80 percent, and above 32 degrees both pumps run flat out while the chiller engages. A failing pump shows as a temperature spread of more than 6 degrees between the first and last module in the row, because flow has dropped and the far plates heat-soak. Pump current draw at full speed is 9.5 Amps at 24 Volts; a reading above 13 Amps means a seized impeller or blocked plate.
| Condition | Primary pump | Secondary pump | Chiller |
|---|---|---|---|
| Pack below 25 C | 40 percent | Off | Off |
| 25 to 32 C | 80 percent | Off | Off |
| Above 32 C | 100 percent | 100 percent | On |
| DC fast charge | 100 percent | 100 percent | On |
| Winter heat mode | 60 percent | Off | Off |
Chiller and Refrigerant Service
When the battery loop cannot shed heat to ambient, the i9 diverts coolant through a brazed plate chiller fed by the cab air-conditioning refrigerant circuit using R134a at a 700 gram charge. The chiller pulls Loop A down to 18 degrees during fast charge so the pack can accept full current without exceeding cell limits. Refrigerant is sealed for life but the chiller core and its two plate seals are service items; a slow pressure loss shows as longer charge times and a pack that caps at 80 percent state of charge in hot weather. The refrigerant low-side should hold 2.5 bar at 25 degrees ambient and the high-side 14 bar; a low-side below 1.5 bar means a leak at the chiller flange that the kit CL-i9-02 resolves with new O-rings and a fresh charge. Treat any drop in low-side pressure as an immediate fault rather than a gradual nuisance, because a weak chiller forces the pack to cap charge current and the truck loses range exactly when the cabin heater is also drawing power.
Winter Heating and Cold Pre-Conditioning
Below 5 degrees the i9 reverses strategy and heats the pack rather than cooling it. A positive-temperature-coefficient heater in Loop A warms coolant to 20 degrees before the morning departure, drawing from the grid during plugged-in pre-conditioning so it costs no driving range. The battery management system holds cells above 10 degrees before allowing full discharge current, and below minus 10 degrees it limits motor torque to 60 percent until the pack rises. Cabin heat is taken from the same Loop A via a heat exchanger, so an i9 parked unplugged in a Scandinavian winter will drain roughly 4 percent state of charge per hour just keeping the pack alive. Pre-condition on the depot charger for twenty minutes and the same cold start costs almost nothing.
Never launch an i9 in sub-zero weather without grid pre-conditioning. A cold pack forced to full current suffers lithium plating that permanently kills capacity, and the torque limiter will make the truck feel faulty when it is actually protecting the cells. Twenty minutes plugged in saves the pack.
Service Intervals and Fluid Replacement
The battery glycol in Loop A is replaced every 4 years or 200,000 km, whichever comes first, because the inhibitor depletes and aluminium plates corrode. The degas bottle is inspected every 20,000 km for level and every 40,000 km for conductivity below 5 micro-Siemens per centimetre; a rising reading warns of plate ingress before any drive fault appears. Pump bearings are not greased in the field and the unit is swapped as a whole using part PP-i9-45 or PP-i9-30. The chiller O-ring set is refreshed at every refrigerant opening. Fleets planning a mixed zero-emission depot should review the SAGMOTO new energy electric trucks range for shared loop parts across the i9 and the lighter i5.
| Task | Interval | Spec or part |
|---|---|---|
| Loop A level check | 20,000 km | 0.5 bar head |
| Conductivity test | 40,000 km | < 5 uS/cm |
| Glycol replace | 4 years / 200,000 km | 50 percent EG mix |
| Pump swap | On fault | PP-i9-45 / 30 |
| Chiller O-rings | Each opening | CL-i9-02 kit |
Because the i9 pack warranty ties directly to cooling care, Shaanxi Fenghan Trading recommends photographing the degas bottle level and logging the conductivity reading at every service, then storing the file against the vehicle serial. A pack that fails below 80 percent capacity inside the warranty window is far more likely to be honoured when the thermal records show disciplined Loop A maintenance, and the cost of the glycol and the meter is trivial against a replacement pack priced in the tens of thousands. Depots that skip the conductivity test lose that defence and bear the battery cost themselves.
Diagnostics and Fault Codes
The i9 battery management system logs thermal faults with a three-digit prefix that technicians read through the depot diagnostic port. Code T01 flags a pump flow below 25 litres per minute and isolates to a failed primary pump or air-locked loop. Code T04 marks a module-to-module spread above 8 degrees and points to a blocked plate or trapped air needing a loop purge. Code T07 is an insulation resistance drop below 500 kilo-ohm, almost always caused by wrong glycol or a cracked plate weeping into the cell cavity. Code T11 records a chiller low-side pressure fault and triggers a charge current cap. Clearing codes without fixing the root cause simply lets the pack drift further from its comfort band, so the loop must be physically verified before reset. Depots running the i9 beside the SAGMOTO new energy electric trucks i5 can share the same glycol drum and conductivity meter across both, simplifying the workshop.
Cabin Loop and Power-Electronics Cooling
Loop B on the i9 cools the motor inverter and the on-board charger rather than the pack, and it shares the chiller only through a heat exchanger so a failure in one loop does not contaminate the other. The inverter demands the tightest temperature band because insulated-gate bipolar transistor junctions age faster above 65 degrees, so Loop B runs a dedicated plate at the inverter and a smaller plate at the charger. Its glycol is changed on the same four-year clock as Loop A but is a separate drum, and the two degas bottles sit side by side with colour-coded caps that the workshop must never swap. A rising inverter temperature fault with a clean battery loop almost always means Loop B pump PP-i9-30 has dropped flow and needs the same swap procedure as the battery primary.
Seasonal Commissioning Checklist
At each season change the i9 thermal loop gets a fifteen-minute commissioning routine. In spring, flush Loop A if conductivity rose over winter and confirm both pumps spin up on a cold start. In summer, verify the chiller engages above 32 degrees and that fast charge holds full current past 60 percent state of charge. In autumn, test the positive-temperature-coefficient heater draws the correct 3.2 kW and that pre-conditioning reaches 20 degrees inside the half-hour window. In winter, confirm the torque limiter lifts once the pack crosses 10 degrees. Recording each check against the vehicle serial builds the evidence trail distributors need to honour the battery warranty, and Shaanxi Fenghan Trading accepts these logs as proof of proper care when processing a pack claim from Xi'an.