StarBMS Smart Precharger

Description

Motor controllers and inverters have a large, low-ESR capacitor bank on their input. Connecting a battery straight to it causes a current spike that can weld contactors or blow fuses.

The Smart Precharger charges those capacitors through a resistor first, then closes the main contactor automatically once they are charged. It stops the precharge and flags a fault if the voltage does not rise (usually a wiring fault or no pack voltage) or if precharge takes longer than 5 seconds (usually a load on the output side).

Resistor options

• 50 ohm: 12-180V nominal packs
• 100 ohm: 180-360V nominal packs

Specifications

• Supply: 8-18VDC (12V nominal, 3A max)
• Typical precharge time: 1-2 seconds
• Built-in coil spike suppression diode
• Size: 71 x 25 x 18 mm

Download the datasheet (PDF)

Built from the open-source ZEVA Smart Precharger (PRECHv1-3) design, released under the MIT License.