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[TenTec] DC Power Supply Backup

To: <tentec@contesting.com>
Subject: [TenTec] DC Power Supply Backup
From: ken.d.brown@verizon.net (Ken Brown)
Date: Wed May 21 23:23:30 2003
>
>
>
>Many remote radio repeaters operate from 12, 24, 36, or 48 volts, directly
>from float-charged batteries.  There is no interruption of service whenever
>the AC power fails... and when the AC power is restored, the float charge
>continues to keep the battery array at the design voltage level.
>  
>
Not quite. When the AC power is restored, if it has been off for a while 
and the radios have been drawing current from the batteries, the charger 
has to supply a high charge current to the battery array, not just a 
float current. For this reason the power supply actually has to be 
capable of providing significantly higher current (some systems are 
designed at 2X) than what the radios need to operate. If it cannot do 
so, the battery won't get charged back up in time for the next power 
outage. Or when the battery is taking a large charging current, and all 
the radios get keyed up drawing full current, the power supply gets 
overloaded, pops a breaker or fuse. It is pretty common for radio 
traffic to be highest at the same time that power outages and recoverys 
are happening.


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