25A Smart Power Supplies
Giraffe have designed a range of mains power supplies suitable for standby use on LiFePO4 battery banks. These are primary designed for use in our own products (tower, battery box) but they can also be sold individually for use in your own products.
Overview
These chargers are designed for standby use. This means that they are designed to be left connected to an LiFePO4 battery bank long term, ensuring that it is kept at 100% capacity.
Charging Profile
The charging profile on the chargers is as follows:
Constant Current (fast charge)
14.2V 25A
Constant current stage starts after mains power is initially connected
Constant Voltage
14.2V
CV stage ends when current falls below 6.2A
Float Charge
13.6V
The charger will remain in float charge until the mains power is cycled.
Note that the charger will not switch from float charge back to constant current after it finishes a charge cycle. It will remain in float charge forever until the power is cycled when it will start a new charge cycle.
The reason for this is that the typical use case for this charger is in a CCTV tower where it is expected to be permanently connected to mains. The assumption is that when the tower is first connected to mains the charger will charge the batteries to 100%. It will then revert to float voltage and the charger will carry the load.
Floating the battery at 13.6V will keep it at 100% without any risk of over charging it.
If the mains power is disconnected, the battery will begin to discharge. When the charger is reconnected, the constant current cycle will start again and the battery will recharge.
We believe this is a better algorithm for long term LiFePO4 battery health than constantly recharging the battery to 14+ volts.
Note that in order to restart a 'fast charge' cycle to 100%, the charger must have it's mains power disconnected for approximately 5 seconds in order to reset it. If the mains power is briefly removed without the LED going out, it will not restart the cycle.
If the cycle is not restarted, the battery will still charge (eventually to 100%) but it will charge much more slowly.
Charging Indication
The charger has a built in indicator light to show it's current status.
Green
Steady
The charger is in float mode
Red
Steady
The charger is fast charging
Red
Flashing
The charger is faulty
Green
Flashing
Not implemented
There is also a sensing wire available externally shown below. This is a 3.3V signal that behaves the same as the green LED.
Wiring
1
12V Charging Output
Connect to battery bank. Brown = +12V Blue = -12V
2
3.3V Sensing Wire (0.5mm2)
Used to determine whether charger is active by a separate system. 10mA max current.
3
Mains Input Wire
Supply 110-230V into the charger.
4
Additional Bonding Wire (4mm2)
Connected in parallel with the mains earth and case ground.
The earth bonding wire can be used to bond the chassis of your device. Note that the bonding wire is in parallel with the mains earth input and it is also connected to the enclosure of the charger.
The charger output negative side is isolated from the mains earth.
The 3.3V sense wire shares it's ground with the charger output negative.
Specifications
Model Number
GL-SPS-300-EU / GL-SPS-300-USA
Part Number
GPN12975 (EU) / GPN13537 (USA)
Input
100-240VAC 50-60Hz
Output Voltage
As specified
Waterproof Rating
IP65
The only difference between the USA and the EU version is the mains wire colours. The EU version has blue & brown cores whereas the USA version has black and white cores.
Troubleshooting
The charger is charging slowly
Remember that in order to start a new charge cycle, you must first switch off the mains power to the charger.
Customisation
We are able to customise various aspects of these chargers:
connectors
charge profile
wire lengths
OEM & white labelling
Please contact us if you would like to discuss.
Revision History
January 2026
We changed the fast charge voltages from 14.4V to 14.2V and the float voltage from 13.7V to 13.6V. We did this because we determined the higher voltages were unnecessary after real life testing.
Last updated