Battery charger

[boris]

I found this product feature
https://dlidirect.com/products/24v-midspan-poe
I think this can be fantastic feature for small installations.


Eliminate the UPSDirectly connect a pair of 12V batteries for uninterrupted power without a separate UPS. The injector senses both battery and AC power, switching instantly to the best power source. The built-in smart charger will float and trickle charge anything from small gel-cells to a pair of car batteries. For quick recharge, fast chargers can be added externally. An updated design with dual voltage regulators ensures that sensitive radios like UBNT receive precisely regulated and protected power.

[GREG3f]

+1

[Charlie]

To achieve this now
Use a DC model netonix connected to a 12V / 24V deep cycle battery.

Then use a "constant current" power supply such as a Mean Well DR-120-12 or DR-120-24 with the output voltage adjusted to the float voltage of the battery. Connect it to the battery also.

The power supply will always output the amount of amps required by the netonix. However if the mains power goes out, the battery will continue to supply the power. You can monitor this by snmp and you will see the netonix input voltage begin to drop.

Once the mains power comes back on, the CC power supply will provide enough power to run the netonix (eg. if using 30 watts of devices, it will supply 2amps @ 12v) but since the constant current limitation prevents it from overloading, it will continue to provide extra amps as required to recharge the battery back up to the float voltage. The mean well DR-120-12 is capable of supplying 10 amps.

Most plain power supplies without constant current limiting will overheat and fail during the recharge process because the battery sucks too much power. This is also what happens when you put large deep cycle batteries on to a cheap desktop UPS
Most smart chargers with trickle function will recharge the battery and then switch to trickle mode which isnt enough to run the netonix / load and so the battery runs flat again.

If you have 30 watts of POE devices, or a 2 amp load through the netonix, then a 12v 120ah deep cycle battery will give you 24 hours of run time during a mains failure assuming the float voltage keeps the battery around the 80% charged mark, and we dont want to discharge below 30% to prevent permanent damage to the battery.