Doosan DL200-5 Parasitic Draw Drains Battery
Fault Codes & Symptoms
Battery dies when parked Related symptoms: - Batteries require frequent replacement. - Slow cranking, especially after sitting. - Alternator may still appear to charge correctly when the engine is running. Machine batteries go dead if it sits for more than a few days. They have to jump-start it every Monday morning. Batteries were replaced last month but the problem continues.
Confirmed cause: Leaking diodes within the alternator rectifier assembly. The diodes were allowing DC current to flow from the battery back through the alternator windings to ground when the machine was off. Repair performed: Replaced the alternator assembly. Verification: With the new alternator installed, the parasitic draw test was repeated. The ammeter showed a reading well within the manufacturer's specified limit after all modules went to sleep. The machine was parked for a week and started normally without a jump-start. Technician notes: - The draw from a bad alternator diode can be intermittent and may change with temperature. - Always perform a parasitic draw test after replacing batteries for this type of complaint to ensure the root cause is resolved. - Isolating the alternator requires disconnecting the main B+ output stud, not just the smaller wiring harness connectors.