For a golf course or community fleet running 48V carts through winter mornings, the practical problem is not total capacity - it is usable energy and safe replenishment in the cold. In this scenario analysis, we show how 国轩吉泰美（GOTION JTM）approaches a 48V ordinary-duty cart conversion: sizing the pack from measured shift energy, keeping BMS peak-current and charge-inhibit logic aligned with the controller and the charger, and validating with logged data rather than assumptions. Catalogue identity such as [product:4825YA] confirms only that we offer a 48V electric-mobility product line; verified project records - not catalogue entries - establish any specific electrical rating.
Scope and operating assumptions
This note covers 48V golf carts used for ordinary course or community duty - typically a Club Car or E-Z-GO platform operated at moderate speeds on mixed flat and gentle-gradient terrain, parked overnight or between rounds. Naming these platforms identifies a common vehicle class only; it is not a claim of fitment, OEM authorization or measured results on any specific model, since controller voltage windows and model-year requirements vary. We assume a stock traction system (controller and motor unchanged), a lithium pack with a battery management system (BMS), and a charging window between shifts. A '48V' lithium iron phosphate pack is commonly a 16-series-cell configuration with a nominal voltage of about 51.2 V and a full-charge voltage near 58.4 V; the exact configuration must be confirmed against the controller's stated minimum and maximum input voltage before any proposal. Where the vehicle supports regenerative braking, the pack must also accept reverse (charge) current in bursts.
Working principle and control logic
The causal chain in a lithium cart pack runs: measured cell voltage and temperature -> BMS protection decision -> contactor/MOSFET state and charge or discharge limits -> release once conditions recover. Three behaviors matter most in fleet duty:
- Peak-current protection: motor controllers draw short, high-current bursts during acceleration and hill climbing. If the pack's current limit is below the controller's peak demand, the BMS disconnects or limits output; the cart loses power mid-climb and may only recover after load drops. Sizing the discharge path to the peak - not the average - is what prevents nuisance trips.
- Undervoltage behavior: as the pack approaches empty, cell voltage falls. A BMS cuts discharge to protect the cells, while internal resistance causes terminal voltage to sag under load well before that. With lead-acid this sag progressively slows the cart; a lithium pack holds terminal voltage flatter through most of discharge, so performance stays consistent until near the end of usable energy.
- Low-temperature charge inhibit: charging lithium cells below the manufacturer's allowed temperature threshold can cause permanent internal damage, so a BMS blocks or limits charging until cells warm. In winter operations this shows up as a charger that appears connected but delivers little or no current. The correct interpretation is protective, not a charger fault; recovery occurs once cell temperature rises above the enable threshold, for illustration after the pack has been indoors or the cart has been driven.
Charging itself must use a lithium-appropriate constant-current/constant-voltage (CC/CV) profile. Lead-acid chargers apply absorption, float and equalization stages; equalization voltage in particular is incompatible with lithium cells, so a retained charger is only acceptable if it has a selectable lithium profile without these stages.
Parameters and interfaces
The core sizing calculation converts task energy into required capacity. Shift energy required, E_shift, is measured or estimated from logged use in watt-hours, including the vehicle's real route, load and gradients. Required nominal energy is then:
E_pack = E_shift × M
where M is a design margin factor (dimensionless), covering hills, cold-weather capacity reduction, driver variation and ageing. Then:
Capacity (Ah) = E_pack (Wh) / nominal voltage (V)
Assumptions: E_shift reflects actual duty, not the old battery's nameplate; nominal voltage is the pack's rated value (e.g., 51.2 V), so the result is nominal energy only - it is not usable energy, range or measured runtime, which depend on discharge rate, temperature, depth-of-discharge limits and BMS cut-offs. The discharge interface must be checked against the controller's continuous current and peak current demand including duration, plus regenerative charge current where applicable; a precharge path limits inrush into the controller's input capacitors at switch-on, avoiding a protection trip at key-turn. On the interface side, CAN communication between pack and vehicle/charger, Bluetooth or app visibility are project-specific options that require per-model evidence before being quoted as functions.
Verification and fault diagnosis
Safe validation relies on data, not on opening packs or probing energized terminals:
- Log duty current: record current and voltage over representative rounds including the worst hill and a full passenger load. This establishes true peak current, its duration, and Wh consumed per shift - the two numbers that drive pack selection.
- Observe loaded voltage: compare terminal voltage at rest versus under peak load. Sag proportional to current and internal resistance is normal; a progressive, accelerating sag across cycles suggests ageing or a connection issue.
- Verify charge behavior: confirm the charger profile is CC/CV lithium with no equalization/float stage, and log charge current versus cell temperature. Charge current near zero in cold conditions should be read against the BMS charge-inhibit logic above before the charger is blamed.
- Check BMS event logs where available: over-current, under-voltage and low-temperature events with timestamps let a service team distinguish protection trips (which recover) from persistent faults (which do not).
- Third-party evidence: cell-, pack- or system-level safety compliance for the specific product should be established from the supplier's documented test records for that exact model, not inferred from chemistry or marketing claims.
Limitations
Catalogue models such as [product:4825YA] or the Zhiyuan-series listings identify our electric-mobility line only; their series names and category placement are not verified electrical ratings, and figures in this note are general engineering relationships, not measured JTM product data. Exact voltage configurations, current limits, temperature thresholds and communication interfaces vary by vehicle and pack design and must be confirmed per project; no exact thresholds are asserted here. Vehicle speed depends on the controller, motor, gearing and legal limits, so a battery change alone does not make a cart faster, and raising voltage (e.g., 48 V to 72 V) requires a validated whole-vehicle design, not a pack swap. Cold-weather range loss remains real even when charging is managed correctly, and margin M must absorb it. If your fleet's logged duty data and charger constraints are shared with our technical team, we can run the matching calculation above against the specific vehicle platform and propose a validated 48V conversion configuration as the next step.