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BG40 Battery Guard - 40A 12/24V

Price:  £79.55   (£66.29 Exc. VAT)

Product code:  P01123



In stock

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Discharging your battery to very low levels can irreversibly degrade its performance and reduce its lifespan by weakening its ability to hold charge and reducing the no. of charge/discharge cycles available. This 40A Samlex battery guard prevents over-discharge by cutting the power to to the appliances once the voltage drops to a user-selectable level, so preventing further discharging of the battery. It also cuts power once the voltage rises to a certain pre-set level to protect appliances connected to your battery from potential damage caused by an over-voltage situation (e.g. faulty alternator or charger).

There are a number of pre-programmed low voltage thresholds that can be selected to suit your application and the battery guard will then automatically cut power at that threshold to preserve the life of your battery. It automatically detects the battery voltage (12 or 24V dc) and has very low voltage drop and standby current draw. It also features connections for a remote On/Off and an alarm/light/relay etc. to indicate it has cut power.


  • Extends battery life and prevents damage
  • Guards against excessive discharge and over-voltage by disconnecting battery
  • Auto-detects battery voltage (12/24V)
  • 10 programmable voltage thresholds
  • Low current consumption
  • Low voltage drop
  • Yellow LED to indicate On/Off status
  • Waterproof
  • Remote On/Off connection
  • Output connection for remote alarm/light/relay etc.

It is recommended that the battery guard be installed in between the battery and a fuse/distribution box, as close as possible to the battery.

Suitable for batteries used in caravans, motorhomes, campervans, boats, off-road, industrial and commercial vehicles with a current draw from the battery up to 40A max.

  • Max. continuous current: 40A
  • Shut-down current: 45A
  • Nominal voltage rating: 12 or 24V dc (detects 8 - 35V dc)
  • Shut-down voltage: 16V (for 12V operation), 32V (for 24V operation)
  • Voltage drop: 0.0875V @ 35A
  • Current consumption: 4mA (2mA when in under/over voltage mode or OFF)
  • Housing material: Anodised aluminium with epoxy encapsulation of electronics
  • Ingress Protection rating: IP66 (dust-tight and protected from powerful water jets)
  • Connections: 2 x M6x18mm studs, 4 x 6.3mm male blades
  • Mounting:  2 x 4.0mm holes in aluminium chassis
  • Weight: 0.2kg
  • Overall dimensions: 80(L) x 60 (W) x 40 (H) mm

Part Number:  BG40

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