[freegeek-ups] plugging UPSs into themselves - got an answer from APC

Cliff Fortune caf at Unions-America.com
Fri Jun 2 13:12:07 PDT 2006

& it is worse than I thought.
Not only could this kill the battery, it could even damage the UPS.

Plugging the UPS into itself is safe if there is no battery in, but 
I say this sends a contradictory/confusing message to the rest of 
FreeGeek, also store customers, so let's keep things simple = SAFE = 
             we will NOT plug UPSs into themselves.

Discussion/Explanation = 
The biggest risk is a "cold-start" which, for those who do not know, 
is where you start the UPS from its own battery without utility power.
This is a feature designed into the UPSs, but the owner manuals say 
that even with good batteries a cold-start is NOT recommended because 
it is so hard on the batteries.  If the UPS is plugged into itself 
during cold-start the UPS circuits will be damaged, says APC.  
A cold-start is easily done by accident, all you have to do is press 
& hold the "TEST" button for more than 2 seconds.  
To stop it, you generally have to open the UPS & unplug the batteries.

I think the donors sometimes do this, because since the beginning 
of my time in there UPSs have sometimes arrived on the incoming shelves 
in this condition, so let's add this to the UPS-EVAL process = 
when a UPS worker 1st arrives for their shift, they must immediately 
unplug any UPSs found plugged into themselves.

We can make Receiving aware of this, but they are usually too busy 
to do more than identify a gizmo type & deliver it to the right part 
of the building, & that is all their job entails anyway, 
so this is UPS-LAND's problem, so let's stay on top of it.


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