FAQ’s & Technical Information

Can I use a DuraComm power supply to charge a battery?

Any of the DuraComm power supplies may be used for battery charging, but in most cases, if the battery is directly and continuously connected, the standard 13.8 VDC power supply output voltage must be reduced to avoid overcharging the battery. Generally, the proper voltage to float charge, (maintain), a 12 volt battery system is 13.2 – 13.4 VDC, for such as a group 27 deep cycle, conventional flooded cell, or AGM type. (A Gel cell type may be floated at 13.6 VDC.) If you intend to use a Duracomm power supply to float charge a battery, please specify when ordering, so we can reset the output voltage. If you already have one of our power supplies that you intend to use for float charging, and if you have a qualified technician available, we can supply instructions for voltage resetting. The same applies to dual battery, 24 volt systems, except the voltage levels are doubled.

If the battery is being used in a back up power system, an alternative to direct connection, is to use one of DuraComm’s Battery Back Up Modules

Can I use a DuraComm power supply in either a negative or a positive ground hook-up?

Yes, in DuraComm power supplies, neither the -V nor the +V output terminal is connected to the cabinet or chassis. They may be used for either negative or positive ground operation, by connecting a jumper wire of suitable size, from either the -V terminal, or the +V terminal, to the frame or chassis ground terminal.


What is Power Factor (PF)?

PF applies only to AC circuits.  It is the ratio of real power (watts) delivered to apparent power (Volt Amps VA or Kilo-Volt Amps KVA).  In AC circuits the voltage is a sinusoidal wave form aka:  Sine Wave.  The current is also a sine wave form.  For maximum power to be delivered the two sine waves must be in phase or “lock step.”  If the two are not in phase the AC voltage will peak before or after the AC current.  This out of step condition will reduce the real power that can be delivered to and used by the load.  The ratio of real to apparent power is the PF, which is expressed in decimal or percentage.  If the real power is 70 watts but the VA is 100 VA, the PF is 0.7 or 70 percent.

An incandescent lamp has a PF of 0.97 or better.  A motor is typically 0.75 to 0.8.  A poor PF will cause excessively high currents and heating of the load.

The power company bills on KVA delivered so maintaining a high PF will reduce your electric bills.

What is “Remote Sense?”

Regulated power supplies sample the output voltage and feed it back for comparison to the internal reference voltage.  The regulator adjusts the output voltage up or down as needed.  Power systems incorporating remote sensing have the capability of sampling the output voltage at the load and feeding back this “information” to keep the voltage constant at the load thus compensating for line losses and other variables of the installation.

What is “Remote Control?”

Remote Control is the ability to bring a power module or system “on line” from another location, either automatically or by manual control using low level signaling, typically 5 volts (TTLogic Level).

What is “Load Share?”

Load Share refers to a special circuit in certain power modules that allows easy paralleling of identical modules for increased current capability.  All the modules load share circuits exchange information (by inter-connect) and adjust the various module voltages slightly to result in near equal current being drawn from each individual module.

Is there a simple way to set up an efficient battery back-up system?

Yes, add-on Battery Back Up Modules,  are available for any DuraComm power supply, to set up a solid state, battery back-up system. The modules use dual Shottky diodes to provide protective isolation and seamless transfer of the load to the battery when the AC mains go down. Fixed resistance is used to reduce power supply output voltage to the battery to the recommended float charge level, (excluding RMBB or MMBB, which require a separate source of battery charging).
For the LP series, use LPBC-25.
For the RM series, use RMBC.
For the DPS series use IQ4 Intelligent Smart Charger
“SC” series are stand alone chargers in 12, 24, 48 VDC

How much battery capacity will I need for my battery back up system?

Three primary factors must be considered to calculate how much battery capacity will be required for communications systems:

• How many amperes the load consumes in transmit and receive.
• The duty cycle of transmit and receive.
• Length of operation from battery power.

Sample, typical information for communications systems, is listed on the tables of System Ah Needs.
For constant load type equipment, multiply the load in amperes times the number of hours of desired battery operation to determine the ampere/hour required of the battery system.

Can I connect multiple batteries to get more capacity in a battery back-up system?

Yes, higher ampere/hour capacities can be achieved by using multiple batteries.

Can I connect two DuraComm power supplies in parallel to increase capacity?

Many of our power supplies can be connected in parallel to increase amperage. However, due to differences in circuit designs and load sharing characteristics, contact us to discuss the intended application prior to implementation. Our technical department will be happy to assist with information on model compatibility and connection techniques.

Can I readjust the voltage output of a DuraComm power supply?

Most DuraComm power supplies can be readjusted by a skilled technician, using an accurate digital voltmeter. The difficulty varies from model to model, so please contact our technical department at 816 472 5544, for specific information.

Can I connect multiple batteries to get more capacity in a battery back-up system?

Yes, fairly high ampere/hour capacities can be achieved by using multiple batteries. Two 12 volt batteries can be paralleled to get more ampere/hours. However, the better method is to series connect two 6 volt batteries. Typically, a 6 volt battery of the same physical size will have double the ampere/hour capacity. For example, the average 6 volt battery used in golf carts is typically rated for 220 ampere/hours. If two of these six volt batteries are series connected, you get a 220 ampere/hour supply, and avoid potential problems that exist with parallel 12 volt batteries. A defective or low cell in either of the 12 volt batteries can drag down both batteries. Also, charging may be uneven, and the greater number of cells increases the chance of cell failure.

If more power than two 6 volt batteries is needed, then four 6 volt golf cart batteries can be used in
a series, parallel, cross connected configuration, to build a 440 ampere/hour 12 volt backup supply. Cross connecting means that the “center” terminals of the series connected batteries are also connected together. This method will better distribute the load and charge currents among the cells and improve battery life.

Still higher ampere/hour capacities can be achieved with larger, group L-16 sized 6 volt batteries.