Battery Parasitic Drain Guard Auto-Disconnect Range

We provide a mobile autoelectrical service engineer callout service in Shropshire and Mid-Wales areas to trace vehicle parasitic battery drain faults which may be causing a car van motorhome or truck battery to discharge overnight or a few days and prevent the vehicle starting.

Vehicle breakdown is often caused by flat batteries.

Battery Current Drain Location using Amp Draw

There are a couple of methods used to locate battery current drain. On vehicles with computer modules a shut down period with the key out and away from the car may be required to allow the vehicle systems to 'go to sleep' and power down..

Check Amp Draw with Ammeter

One method is to place an ammeter or (amp clamp around the cable) test device in line with the circuit to be checked and one by one disconnect circuit fuses, wiring, or components until the current draw disappears.
On complex modern vehicle wiring systems this is problematic because fault codes can be logged requiring suitable diagnostic equipment to reset control modules.
More problems occur due to difficult of access to wiring looms and components in restricted areas. As the faultfinding becomes more complex time and costs increase.

Check Amp Draw using Voltmeter

An alternative method to locate the source of vehicle parasitic current drains involves checking the Millivolt (Mv) drop across each fuse in the vehicle.
A main point to remember is the higher the current rating of the fuse the greater the current passing through for a given Mv reading.

Again this method of fault detection is problematic where a single fuse supplies power to multiple circuits. Identifying the faulty wiring circuit requires more time consuming autoelectrical work and costs of faultfinding can outweigh vehicle value. Some faults take hours and hours to locate.

Parasitic Current Draw Rectification

A permanent repair involves detective work to locate and renew or repair the fault causing the battery current draw.

A temporary solution to preventing spurious current draws causing low battery voltage can be to fit a battery guard low voltage protection device.

Battery Isolator Switch

A battery isolator switches disconnect battery power.

Battery Guard

The function of the battery sentry is to disconnect power to circuits at a pre-set voltage which still allows the vehicle engine to be started.

Voltage Sensitive Relay

A voltage sensitive relay functions to disconnect a circuit until a preset voltage is reached which triggers the relay contacts to close allowing power to flow to the second circuit.