Pre-Charge Resistor/Switch

When a battery is first connected to an Inverter, the Inverter's capacitors fill quickly with charge. That causes the battery to provide hundreds, potentially thousands of amps for a brief moment. During that moment, the BMS inside of the lithium battery is likely to open circuit. This is the BMS protecting itself from what it believes is a short circuit.

So how do we remedy this? Two options:

1. Use additional batteries. The batteries will share the load, reducing the amount of amperage each battery provides. 
2. Use a pre-charge resistor. This charges the inverter's capacitors slowly.

How do you use it?

1. Install one wire on each side of your system's main battery disconnect switch. 
2. With the main disconnect OFF, press and hold the red button in for 5 seconds. 
3. Turn the main disconnect ON.
4. Release the red button.

Mobile Solar Consulting's Pre-Charge Resistor is made in-house and comes with 2 x 18awg leads, each a 2.5ft length with a 3/8" ring terminal. This is approved for use with 12V and 24V battery systems. It has not been tested with, and is therefore not approved for use with 48V battery systems. 

Measures 4.25 x 4.25 x 3"