Projecta PDC25
25 Amp, 3 Stage Switchmode DC to DC Battery Charger
12V Auxiliary Battery Charging System
The Projecta PDC25 is a 25A DC to DC battery charger designed to charge 12V auxiliary batteries from 12V or 24V vehicles.
The PDC25 can charge from the vehicle alternator and can also accept solar input. When both alternator and solar inputs are available, solar input takes priority. If solar power is not sufficient to support the load, the PDC25 can draw power from the alternator automatically.
The charger is suitable for auxiliary battery charging in vehicles, caravans, 4WDs, trade vehicles, and touring applications.
The PDC25 includes the following features:
25A maximum charging output
Suitable for 12V auxiliary batteries
Compatible with 12V and 24V vehicle alternator systems
Solar MPPT input
Dual input operation from alternator and solar
3-stage charging: bulk, absorption and float
Multi-chemistry battery support
Battery temperature monitoring
Voltage drop compensation
Spark-free protection
Reverse connection protection
Over and under voltage protection
Over temperature protection
Remote LED status indicator output
The PDC25 supports the following 12V auxiliary battery types:
Lithium
AGM
Wet
Calcium
The correct battery type must be selected using the Mode Button on the charger.
Yes.
The PDC25 supports lithium batteries when the lithium battery type is selected.
Yes.
The PDC25 supports calcium batteries. When calcium mode is selected, the charger can provide a periodic equalisation stage to assist with removing acid stratification.
Calcium mode may also be suitable for some deeply discharged calcium-calcium lead acid batteries, but the battery manufacturer should be consulted if unsure.
The PDC25 uses a 3-stage charging process:
Bulk Charge — Delivers higher current to recharge the battery quickly.
Absorption Charge — Maintains controlled voltage while charging continues.
Float Charge — Maintains the battery at a safe voltage once charging is complete.
For calcium batteries, an equalisation stage may also be used.
The PDC25 can provide up to 25A charging current, depending on the input source, battery condition and installation.
The PDC25 supports solar input up to 400W.
No.
The PDC25 has a built-in MPPT solar regulator.
A separate solar controller is not required. If portable solar panels are being used, any solar controller fitted to the panel must be bypassed before connecting to the PDC25.
The PDC25 uses Maximum Power Point Tracking, MPPT, technology to maximise power from the solar panels and improve charging efficiency.
When solar input is available, it takes priority over alternator input.
The manual lists the following solar panel fuse recommendations:
120W — 15A fuse
160W — 15A fuse
200W — 20A fuse
240W — 30A fuse
360W — 50A fuse
Solar input must not exceed the charger’s maximum solar input rating.
Yes.
The PDC25 can be used with smart alternator vehicles when the ignition override cable is connected correctly.
For smart alternator vehicles, the ignition override cable must be connected to the vehicle ignition. The charger will then operate only when the ignition is turned on.
Yes.
For fixed-voltage or temperature-compensating alternators, the ignition override cable can be left disconnected and taped.
Press the Mode Button on the front panel until the required Battery Chemistry LED is flashing.
Then repeatedly press the Mode Button until the correct battery type LED is flashing.
Leave the button for approximately 4 seconds. The selected battery type will be saved automatically.
Yes.
The selected battery type is stored in memory and will be retained even if the PDC25 is disconnected and reconnected.
The default battery chemistry is AGM.
Green flashing — Bulk charge
Green flashing with battery type LED solid — Absorption charge
Solid green with blue flashing — Equalisation charge
Solid green — Float charge
If the input is out of operating range, the charger may enter power saving mode.
Typical indication:
Alternator LED flashing every 8–10 seconds
Solar LED flashing every 8–10 seconds
Battery type LED flashing every 8–10 seconds
This generally means the input is outside the required operating range.
Possible fault: The unit is faulty.
Recommended action: Check if there is any output current from the unit.
Possible fault: Bulk charging time out.
Recommended action: Auxiliary battery may be faulty or heavily discharged. Check the battery over a long time.
Possible fault: Output battery is reversely connected.
Recommended action: Check output cable connection.
Possible fault: Overvoltage detected at output.
Recommended action: Check auxiliary battery voltage.
Possible fault: Output open circuit or bad battery.
Recommended action: Check cable and battery connections.
Possible fault: Solar input is reversely connected.
Recommended action: Check solar input connection.
Possible fault: Overvoltage detected at solar input.
Recommended action: Check solar panel open circuit voltage.
Possible fault: Alternator input is reversely connected.
Recommended action: Check alternator input connection.
Possible fault: Overvoltage detected at alternator input.
Recommended action: Check vehicle battery voltage.
Check the following:
The starter battery voltage is within operating range.
The auxiliary battery is connected correctly.
Input and output fuses are fitted and not blown.
The earth connections are secure.
The ignition override wire is connected correctly if used with a smart alternator.
All cable connections are clean, tight and correctly crimped or soldered.
The PDC25 may not detect sufficient input voltage.
Possible causes include:
Input voltage is too low.
Cable size is too small for the installation.
Voltage drop is too high.
The vehicle ignition is off when ignition override is required.
The fuse is blown or not installed.
Input wiring is incorrect.
This can occur if the auxiliary battery voltage is very low or the battery is deeply discharged.
If the auxiliary battery voltage is below approximately 5V, the charger may not detect it. In this case, the battery may need to be charged externally or checked by a qualified technician.
Possible causes include:
The battery is already fully charged.
The battery has taken a surface charge.
The battery has a faulty cell.
If the battery quickly shows fully charged but does not hold charge, test the battery condition.
The charger includes short-circuit protection. It may not show output unless it is connected to a battery correctly.
To test operation, connect the charger to a battery following the correct installation process and confirm that battery voltage increases during charging.
Surface charge can occur when a battery has been left discharged for some time and builds resistance to being recharged.
The charger may initially see a short period of charging and then detect the battery as fully charged. After several hours, the battery may accept charge more normally.
In a 12V lead acid battery, a faulty cell can prevent the battery from reaching or holding proper charge.
If one cell is faulty, the battery may appear to charge incorrectly or may not hold charge. Battery testing is recommended if a faulty cell is suspected.
Mount the PDC25 in a suitable location protected from excessive heat, water, vibration and direct impact.
The charger should be installed close to the auxiliary battery where possible. It should not be installed near high-temperature components.
For wiring up to 12 metres, the manual lists the following minimum cable sizes:
Alternator input cable: 8mm²
Solar input cable: 8mm²
Output cable: 8mm²
Common ground cable: 8mm²
Ignition override cable: 1–1.5mm²
External LED cable: 1–1.5mm²
For installations longer than 12 metres, technical advice should be obtained.
Yes.
Suitable fuses must be installed close to the battery or input source.
The manual specifies 50A fuses for alternator input and output wiring. Solar fuse size depends on the solar panel wattage.
Before installing or using the PDC25:
Read the instruction manual fully.
Do not attempt to charge non-rechargeable batteries.
Do not charge frozen batteries.
Ensure adequate ventilation around batteries during charging.
Keep flames and sparks away from batteries.
Do not allow young children to use the appliance.
Use suitable cable, fuses and installation practices.
Avoid touching the charger surface during operation, as it may become hot.
Explosive gases may escape from batteries during charging. Always use caution when working near batteries.
The PDC25 is covered by a 5-Year Warranty against defects in materials and workmanship under normal use.
Warranty does not cover damage caused by misuse, abuse, incorrect installation, incorrect operation, modification, or failure to follow the product instructions.
If the issue continues after completing the troubleshooting steps, stop using the charger and contact Projecta support.
Please provide:
Product model: PDC25
Auxiliary battery type and size
Vehicle voltage: 12V or 24V
Solar panel size, if connected
Description of the issue
LED status shown on the charger
Photos of the installation and wiring
Battery voltage readings at starter battery and auxiliary battery.