Battery pack pre-charger selection

Why do high cell count batteries need a pre-charge circuit?

High cell count battery systems often use pre-charged circuits to limit inrush current prior to the main discharge MOSFET turning on which connects the load to the battery. Controlling this inrush current with a pre-charge circuit protects the system from damage, extends lifespan, and increases reliability.

Does a precharge contactor have to be rated for full battery voltage?

Since the precharge circuit is directly connected to the battery, both the contactor and the resistor must be rated for full battery voltage. The precharge contactor and resistor must also be able to handle the precharge current and power dissipation.

What is a pre-charge current?

During the first stage a pre-charge current is applied if the battery is deeply battery. The pre-charge current is usually set to 10 percent of the fast-charge current. Once the battery voltage is greater than 2.8-3.0 V, the second stage of charging can be performed using the fast-charge current. discharged (usually below 2.8 to 3 V).

Where is the precharge circuit located?

The precharge circuit is commonly found on the positive leg, but it could just as easily be installed on the negative leg. Since the precharge circuit is directly connected to the battery, both the contactor and the resistor must be rated for full battery voltage.