A pair of power supplies that are capable of pulling the load and charging the 
battery.

For example, if you needed 200 watts for your 24 volt loads, you need 8.3 amps. 
 Round that up to 10 amps.
Then you have to decide how long you want this thing to last without commercial 
power.  I would think 24 hours is a minimum.  So 10 amps x 24 hours is 240 amp 
hours of battery.
It is always a safe figure to charge a battery at .1C or 10% of its capacity or 
less.  That would be 24 amps to charge the batts after a power outage, plus 10 
for load = 34 amps of power supply.  You could get by with 20 amps, just will 
take a bit longer to charge.

Lots of 20 amp 28VDC power supplies out there.  
Rule of thumb double your load power or more to size the charger.  

From: SmarterBroadband 
Sent: Wednesday, March 09, 2016 11:45 AM
To: [email protected] 
Subject: [AFMUG] Small DC Site

What are people using to power small DC sites.  Option 1 up to 150 - 200 Watts, 
option 2 up to 300 – 400 Watts.  I’m looking for a DC UPS that can charge 
attached batteries.  Need to have 24 and 48 volt.  

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