LVD - Good unit that won't break the bank.

Load Controller
The C-Series controller can operate as a Low Voltage
Disconnect (LVD) for DC loads to prevent over-discharge to
batteries during periods of poor charging or excessive loads.
The C-Series controller uses the user-adjustable setpoints to
determine when to disconnect or reconnect loads depending
on battery voltage.
When used as a DC load controller, the settings of the LVR
and LVD are controlled by two rotary potentiometers (also
called pots) on the circuit board.
The scale on the adjustment potentiometers differ from the
scale used for other functions. A decal with the appropriate
adjustment scale is included with the C-Series. To apply the
decal, gently pull off the knobs of the potentiometers and
place this decal on the circuit board. After the decal is in
place, replace the knobs. The EQ jumper determines manual
or automatic reconnect when the C-Series is used as a load
controller. Do not use this decal if using the C-Series
controller as a PV Charge Controller or Diversion Controller.
Low Voltage Disconnect
When configured as a load controller, the C-Series controller
will disconnect the load from the batteries when it reaches the
LVD setting. There will be a 6-minute delay after the voltage
drops below the Low Voltage Disconnect (LVD) setting
before the controller actually disconnects the load.
Low Voltage Reconnect
It can also provide automatic reconnection of the loads at the
LVR (Low Voltage Reconnect) setting. Reconnection of the
load is allowed once the battery voltage has exceeded the
Low Voltage Reconnect (LVR) setting.
Loads are either automatically or manually reconnected when
battery voltage exceeds the Low Voltage Reconnect (LVR)
setting for 6 minutes.
See “Operating Mode Jumper” on page 20 for instructions on
enabling this mode.