REC Programmable Pre-charge Relay & Bi-stable Relay Driver V3.1

The REC pre-charge module (PCM) combines two functions:

1. pre-charges the capacitors in an inverter with a controlled current flow, and
2. after a settable period of time, 1, 2, 4 or 8 seconds, it turns on the main contactor, either a standard relay, eg Tyco EV200, or bi-stable type, e.g Blue Sea Systems ML remote battery switches (these are high-side switched)

A note on controlled current flow.   Without pre-charging capacitors, the spike of the inrush current is only limited by 1) the ratio of the battery voltage to the 2) total resistance between and including the battery and the capacitors (which is very low with most of the resistance being that of the cables).  **  Recall Ohm's law, ie current I = V/R, so for example at 48V battery voltage, the spike will be 4x that compared with a 12V battery.  Besides the possible non-visible stressing of the battery and capacitors, the spike can be enough to start pitting on the surface of the contactors.  The current I reduces as the voltage at the capacitors increases.

The bi-stable relay driver function of the PCM operates on the high side of the bi-stable relay so that it can be used with the Blue Sea Systems ML remote battery switches.  This function differs to the REC Bi-Stable Relay Driver (BSLRD) which is for low-side driven bi-stable relays.

• robust and small design
• low power consumption @ 11-80 V DC
• 1/2/4/8 s DIP switch delay settings
• Up to 120 V, 4.0 A pre-charge
• integrated 15 and 30 Ω power resistor + 10 Ohm NTC
• 6.0 A top side coil drive with over-current protection
• Single pole or bi-stable latching contactor drive (for Blue Sea ML remote battery switches)
• reverse polarity protection
• over-voltage protection
• one-year warranty

The manual is available here:  Manual for REC Pre-charge Module