Why can't the engine start when the BYD F3DM runs out of battery?

[DeKaden]

When the BYD F3DM runs out of battery, the engine definitely cannot start because the ignition system requires electricity. Below is relevant information about the BYD F3DM: 1. Positioning: As a global leader in new energy vehicles, BYD has been active in the electric vehicle sector. Following its collaboration with Mercedes-Benz, BYD officially announced that the technologically advanced BYD F3DM Low Carbon Edition dual-mode electric vehicle was launched on March 29, 2010. Official images reveal that the vehicle is equipped with a new roof-mounted solar charging system. 2. Powertrain: In terms of powertrain, the BYD F3DM dual-mode electric vehicle is powered by a BYD371QA all-aluminum engine with an output of 50KW, paired with a 75KW electric motor, resulting in a combined output of 125KW. In pure electric mode, the F3DM dual-mode electric vehicle achieves the world's longest range of 100km at that time.

[DelBrooklyn]

For the BYD F3DM hybrid vehicle, the main reason the engine won't start is likely due to a dead small battery. Besides the large battery used for driving, this car also has a 12V small battery responsible for starting the engine and controlling the system. If the small battery is depleted, even if you press the start button, the engine won't work. I've encountered a similar situation before, and it was immediately resolved after jump-starting. Additionally, the car's intelligent protection system might also come into play. When the large battery's charge is too low, it prevents the engine from starting to avoid damaging the battery. In such cases, it's best to plug in the charger for half an hour and then try switching to hybrid mode to start. When parking, try not to drain the battery completely; keeping at least 20% charge is the safest practice.

[LeFrancisco]

The core of this issue is the status of the small battery! My own F3DM had the same problem when the battery was depleted last time. The hybrid vehicle's engine starts using the 12V battery, not the main battery. Try turning the key to see if the dashboard lights up. If it's particularly dim, the small battery is dead. Check if the battery terminals are oxidized or loose. Use a multimeter to measure the voltage; if it's below 12V, you'll definitely need a jump start. Additionally, there might be an issue with the hybrid control module, such as a blown fuse or a bug in the control program. The easiest solution is to call for roadside assistance for a jump start and have the technician check the system for error codes.

[StAnthony]

Operating the F3DM requires attention to procedures. Engine failure to start can sometimes be a mode-switching issue: When the vehicle completely runs out of power, first shift to P gear, then long-press the EV button to forcibly switch to hybrid mode. Wait until the READY light illuminates on the dashboard before pressing the accelerator. If the battery level drops to the critical threshold, the system enters a protective lockout state. In this case, plugging into a 220V household power supply to charge for half an hour will unlock it. Always check if there's fuel in the tank—without fuel, the engine certainly won't operate. My advice is to start the engine at least once a week and run it for twenty minutes to charge the battery and lubricate mechanical components.

[VanBrynlee]

Don't panic, troubleshoot from simple to complex. First, check if the small battery terminals are corroded—try cleaning them by pouring some cola over them. Then inspect the engine compartment fuse box, locate the fuse labeled ECU or HVAC, pull it out and examine it. If the metal strip inside is broken, replacing it with a new one for about ten yuan might solve the problem. Operationally, make sure to turn the key to the ON position and wait for the self-check to complete before starting. It's normal for hybrid cars to start slowly—wait an extra ten seconds before turning it off. If all else fails, jump-start the car, but be careful not to reverse the positive and negative terminals. Long-term parking can cause battery sulfation and damage, so it's recommended to take the car for a spin at least once a month.

[DeLillian]

This needs to be explained from the characteristics of the hybrid system. The design logic of the F3DM is to prioritize electric power, with the engine automatically starting to supply power when the main battery is depleted. However, if the 12V battery is also drained at this point, it creates a deadlock. One method I used to rescue the car was to borrow a power bank-sized emergency power source, clip it onto the small battery, and press the start button to immediately start the car. Another possibility is a high-voltage system failure, such as a temperature sensor falsely reporting high temperatures, forcing the system into protective mode and cutting off the engine. In such cases, it's necessary to go to a 4S dealership for computer diagnostics. It's important to develop the habit of turning off the air conditioning and lights before shutting down the engine to reduce the burden on the battery.