Why won’t your golf cart move after charging? Common culprits include undervoltage lockout (BMS protection), controller faults, or charger errors misreporting full charge. Check battery voltage with a multimeter—72V systems should read 72–84V post-charge. If voltage is normal, inspect the solenoid, throttle sensor, or motor brushes. Thermal overloads from prolonged charging can also trip safety cutoffs. Always verify connections and reset the BMS before troubleshooting complex components.
Why does my golf cart show full charge but won’t move?
This usually indicates a voltage discrepancy or BMS lockout. Snippet: Use a multimeter to confirm pack voltage. If below 72V (LiFePO4), individual cells may have failed, triggering the BMS to disable output. Chargers sometimes falsely report “full” due to faulty voltage sensors or unbalanced cells.
Deep Dive: Start by measuring the battery’s post-charge voltage. A 72V LiFePO4 pack should stabilize at 84V (±0.5V). If it reads 60V, one or more cells have likely dropped below 2.5V, forcing the BMS into protection mode. Pro Tip: Test voltage under load—connect the cart’s headlights and recheck. If voltage plunges, a weak cell group is dragging the pack down. For example, a 72V pack with 22 cells (3.2V each) might have two cells at 2V, creating a 66V total that tricks the charger into stopping early. Transition: Beyond voltage, consider charger behavior. Modern smart chargers communicate with the BMS—if that link fails (corroded pins, broken wires), the charger might display “full” without actually delivering energy. Always inspect the charge port and wiring harness. Rhetorical: But why would voltage drop immediately after charging? Blame unbalanced cells or a defective BMS bypassing low-voltage groups during charging.
Could the motor controller block movement post-charge?
Yes, controllers often reject voltage spikes from charged batteries. Snippet: A fully charged 72V LiFePO4 battery hits 84V—controllers rated for 72V nominal may interpret this as an overvoltage fault, shutting down to protect circuits.
Deep Dive: Golf cart controllers have upper voltage limits, typically 10–15% above nominal. A 72V controller might cut off at 90V, but transient surges during acceleration can exceed this. For instance, regenerative braking could push a charged pack to 87V, tripping the controller’s safety. Pro Tip: Test the controller’s voltage tolerance with a variable power supply—gradually increase from 72V to 84V while monitoring for error codes. Transition: Controllers also monitor throttle signals. If the throttle’s hall sensor malfunctions post-charge (moisture ingress, connector loosened during charging), the controller won’t engage. Practically speaking, reseat all throttle and pedal connectors. Rhetorical: What if the controller itself was damaged during charging? Lightning surges or charger ripple voltage can fry MOSFETs. Use a voltmeter to check controller input/output—24V on the solenoid side and 5V throttle signal are key indicators.
| Controller Issue | Symptom | Solution |
|---|---|---|
| Overvoltage Lockout | No power, error code E05 | Use charger with smoother CV phase |
| Throttle Signal Loss | Cart jerks but doesn’t move | Replace hall sensor or pedal assembly |
How does the solenoid affect post-charge operation?
A stuck or burnt solenoid breaks the high-current circuit. Snippet: The solenoid acts as a relay—if its contacts weld shut or corrode, power won’t reach the motor despite a charged battery.
Deep Dive: Solenoids in golf carts handle 150–300A surges. After repeated charging cycles, their copper contacts can carbonize, creating resistance. Test by bridging the solenoid’s main terminals with a jumper cable—if the cart moves, replace the solenoid. For example, a 72V Club Car solenoid with pitted contacts might drop voltage to 45V under load, starving the motor. Pro Tip: Listen for a click when pressing the pedal—no click means the solenoid coil isn’t energizing. Check the activation circuit’s 12V supply. Transition: Beyond physical wear, solenoids rely on the controller’s logic. If the controller detects a fault (e.g., overvoltage), it won’t send the activation signal. Rhetorical: Why would charging impact the solenoid? Heat from prolonged charging can warp its housing, misaligning internal components.
Can a BMS permanently disable the battery after charging?
Yes, repeated overcharge events trigger BMS hard locks. Snippet: Most BMS units log errors like cell overvoltage (≥3.65V for LiFePO4). After 3–5 incidents, they may require a full reset via manufacturer software.
Deep Dive: During charging, if one cell group reaches 3.65V before others, the BMS stops charging. But faulty cell balancing can let multiple groups exceed limits, tripping a permanent fault. For instance, a 72V battery with 22 cells might have cell 15 at 3.8V while others are at 3.4V—this triggers a BMS lockdown. Pro Tip: Use a Bluetooth BMS dongle to check cell voltages without disassembling the pack. Transition: Some BMS models enter sleep mode if the pack sits idle post-charge. A quick discharge/recharge cycle (5–10 minutes) can reboot them. Rhetorical: What if the BMS itself is fried? Chargers without voltage regulation can send 90V+ into a 72V BMS, frying its MOSFETs.
| BMS Fault | Indication | Fix |
|---|---|---|
| Overvoltage Lock | Red LED blinking 3x | Balance cells manually |
| Communication Error | No LED activity | Replace BMS or wiring |
Does overheating during charging cause motor failure?
Indirectly—thermal expansion warps motor brushes/commutators. Snippet: Charging generates heat; if batteries or motors exceed 60°C (140°F), components degrade. Post-charge, warped brushes lose contact, stalling the motor.
Deep Dive: Golf cart motors rely on carbon brushes transferring current to the armature. Excessive heat from charging (e.g., fast charging at 20A in 35°C ambient) softens the brush springs, reducing contact pressure. Example: A 48V motor upgraded to 72V without brush upgrades might see brushes wear 50% faster. Pro Tip: Post-charge, feel the motor housing—if too hot to touch (>65°C), install a cooling fan. Transition: Heat also affects motor windings. Insulation breakdowns from repeated overheating create short circuits, drawing excessive current that the BMS blocks. Rhetorical: Why wouldn’t this appear until after charging? Residual heat lingers, compounding during the next discharge cycle.
Battery Expert Insight
FAQs
Disconnect the charger, turn off the battery for 10 minutes, then hold the pedal for 5 seconds. If unresolved, consult the BMS manual for a hard reset (often requires a jumper wire).
Can a car charger fry my golf cart battery?
Yes—car chargers operate at 12V–14V. Connecting to a 72V system creates a reverse current, potentially damaging the BMS or cells. Use only golf cart-specific chargers.
Why does my cart work after cooling but not post-charge?
Heat expands internal components, creating temporary opens in motor brushes or solenoid contacts. Let the system cool for 1–2 hours before retrying.
