Third-party or custom power supply

25 Feb 2010

Caution: Any damage caused to a Juniper Systems product by the use of an unauthorized third-party or a custom-built power supply is not covered by the standard product warranty. Information below related to finding a compatible third-party power supply or creating a custom power supply shall be used at your own risk.


Standard Power Supplies

We recommend using the standard power supplies (e.g., wall charger, cigarette lighter adapter, power dock, rechargable battery, external battery charger, Allegro AA alkaline battery holder, HarvestMaster HM-400 System Power Cable) that are shipped with the product or that can be purchased as optional accessories from Juniper Systems or an authorized product reseller. These standard chargers have been certified with our products in many countries to comply with radio noise/interference and power requirement laws.


Extended Battery Life

For more information about recommended options for extending the battery life of your Field PC, please visit our "Extended battery life" FAQ web page.


Charging Port

An external power supply should only be connected to the charging port of the Field PC. High currents should not be applied to any other ports or card slots of the Field PC.

Note: Limited power can be supplied to accessory devices from the Field PC through some of the ports and card slots. For more information, please visit our "Power supply for accessories through ports and card slots" FAQ web page.

The specifications of the Field PC charging port are as follows:

Please refer to the image below for more information.



If you can not obtain a connector that fits properly in the charging port of the Field PC, you can modify a vehicle (cigarette lighter) charger that can be purchased from Juniper Systems or a product reseller.


Power Requirements

The Field PC requires up to 800 mA (~10 watts) at 12 V (possibly up to 20 V) DC from the attached power supply. Make sure the power supply can provide a minimum of 800mA to ensure the Field PC does not exceed the maximum output of the power supply.

The HarvestMaster HM-400 harvest system sometimes requires up to 4A at 12 V DC, depending on the actuators being used on the attached bucket system. We recommend using the newer, black power cable that has a right-angle connector. If you are using the old, thinner black power cable (without a right-angle connector) at lengths greater than 10 feet, voltages may sag, potentially affecting the accuracy of moisture readings.


External Batteries

If you do not have access to a cigarette lighter port on a vehicle for connecting the standard Field PC vehicle charger, or if you are connecting a HarvestMaster HM-400 system, the positive and negative terminals of a vehicle (lead-acid) 12 V DC battery can be connected directly to the Field PC`s charging port, or to the HM-400 power supply cable.

WARNING: If connecting to a 12 V battery that is also being used to operate the vehicle, make sure the battery does not drop below 10 V or jump to above 18 V during activities such as starting or shutting down the vehicle. This could potentially damage your Juniper Systems product or effect normal operation. Though our products have power protection circuitry, disconnecting the Juniper Systems product(s) during such activities or installing a 10 or 15 amp fuse may be the safest option.

Other battery types and chemistries (such as large gel cel camcorder batteries) may also be used as long as they meet the power requirements of the Juniper Systems product. For more information about battery types and chemistries, please visit the Battery University website.

Other potential power sources may include solar panels, generators (pedal, crank, etc.), and many others. Make sure that any power source you use meets the above mentioned specifications before connecting to a Juniper Systems product.