User and installation manual

Page 5 of 23

Congratulations, you will soon be using the most efficient controller available. Using this

controller has the direct equivalency of increasing your solar panel capacity by up to 20% over

any other controller Flexcharge

USA has examined. This controller is available with

capacities to 2000 amps with the same, or increased charging efficiencies.

NOTE: The NC25A does not contain any blocking diodes.

IMPORTANT:

PLEASE READ THE SECTION "USING BLOCKING DIODES" Pg.10

1) Choose a good mounting location.

Even though the controller has been designed for mounting outside, mounting it in a more protected

environment will help to extend it's operational life.

2) Install the NEGATIVE BATTERY SENSE WIRE from the controller's terminal block to the

battery bank negative (-) terminal. You should use #16 to #14 awg black wire.

3) Install the POSITIVE BATTERY SENSE WIRE from the controller's terminal block to a 1A or 2A

fuse and then to the battery bank's positive (+) terminal. You should use #16 to #14 awg

yellow or red wire.

IMPROTANT

When installing the terminals on to the sense wires for connection to the battery, crimp then

solder the terminals to the wire. Make absolutely sure these wires make very good electrical and

mechanical connection with the battery's terminals. If either of this or the ground connections were to

loosen, or corrode, the controller will have no way to sense battery voltage, causing it to switch to a

non-regulating mode and overcharge the batteries. The sense wires may be extended up to 100 feet

using #14 or larger wire. All splice joints must be soldered. If you are charging multiple isolated battery

banks through a battery isolator, connect the SENSE wires to the primary (most used) battery bank.

The other batteries will follow the primary battery's voltage, and will not be over or under charged.

IMPORTANT

For the next four steps, see the Wire Size Table on page 9 to select the correct size wire for your

charging current and length of wire.

4) Connect the charging source negative (-) wire to the negative (-) terminal on the battery

and/or the system's negative battery bus. If you are using a smart battery fuel meter that

measurers total Input to Output Amp/Hours, it will usually have a shunt in the (-) connection to the

battery. Connect the (-) wire from the charging source to the shunt as shown in the meter’s manual.

5) Install the BATTERY POSITIVE (BAT. +) wire from the controller to the battery's positive

terminal. A fuse rated at 1.5 times larger than your maximum charging current, but less than

30A, should be installed in this wire near the battery. Remember to solder all wire connectors

even if they use crimped connectors.

INSTALLATION INSTRUCTIONS

Flexcharge

USA NC25A

ULTRA HIGH EFFICIENCY CHARGE CONTROLLER