When the engine is running in a steady state and the negative terminal of the battery is disconnected: Should the alternator power the engine (the engine should continue running)?

1 Answer 1


In most cases, yes. However ...


Why? While it won't happen every time, you run the risk of killing your alternator, as well as other electrical components in your vehicle.

  • Ok. Won't do it. What exactly happens that causes damage?
    – gatorback
    Commented Jan 15, 2023 at 23:14
  • @gatorback - The battery serves a couple of purposes. It provides the field charge for the alternator so it can actually work. It also serves as a buffer for transient spikes which may occur for whatever reason. In a worst case scenario, a transient spike can go up several volts, then drop (or visa versa). When you take the battery out of the charging loop while the engine is running, those spikes can occur and cause major havoc throughout your entire electrical system. Just taking the battery out of the loop can cause the transient spike to occur. Commented Jan 16, 2023 at 0:19

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