[aprssig] 8 hour Backup Power Rule

Rich Garcia k4gpsc at gmail.com
Mon Mar 17 20:24:32 EDT 2008

This is kind of (more like really) off topic but I got to chime in with some
first hand expirience.

I can not speak for all cellular companies since I do know of some that are
really off the wall but MOST look at it this way.

Batteries ARE JUST for when fit hits the shan. Most cell sites will operate
off of batteries 24/7 but are charged off of the AC mains. If you lose power
the generator will kick in about 5 seconds and the transfer switch will kick
in about 10-30 seconds after that. So for MOST cellular sites battery
capacity/drain is only needed for a minute at most, since they will charge
off of the mains or generator via 24 or 48v rectifiers. Large cell sites
will draw about 340-450 amps at 24v, give or take on the model.

Batteries will do you diddly squat at indoor sites. When the power goes away
and the cell site continues on your "8 hours" of battery and generates heat
most huts will reach 150 degrees in 1 hour or less. Make that not 150
degrees, make that meltdown! Battery backup is WORTHLESS unless it is an
outdoor cabinet or you are in a VERY VERY cold enviroment. Huts are very
close to air tight to get dust and insects out and use a closed air A/C
system. Even with 25-32 degree outside temp's you will see the indoor temps
go up above the usual high temp of 90 deg in 1 hour or less depending on the

$15,000 will buy you a CHEAP 40kw generator, it will sit there forever since
it will not cover the installation, fuel or regular maint. 40kw generators
will power the average town site, 10x25 building and 2 A/C units. Go to a
city site, make that a 15x30 shelter, 2 larger A/C units, possibly Microwave
equipment, and additional capacity (ie: More Amplifiers) and you will need
to install a 80-100kw generator. You are looking for equipment alone in the
$25-$30k range plus installation and supplies. By the way an average
generator fuel tank will hold about 2.5-3 days of fuel, some parts of the
country use natural gas and many parts of the south with wetlands use
propane tanks. Propane fuel averages about 1-2 days (AT MOST)of fuel.

Several cellular companies have been working towards a standard of 8 hours
for many years now, this FCC (or Katrina)thing is nothing earth shattering
for many, but yes one of the vocal opponents to the FCC memo do not have
generators at all but a hand full of sites and have less batteries than most
of us hams do. Anyone in the industry know who they are. Just enough to hold
a site up for a flicker in the power mains without going through a re-boot.
For some sites (ie:Rooftop or Wetlands with no Diesel allowed)companies are
working towards 12 hours of backup batteries. So you either can't pull a
permit for diesel due to managed wetlands, or you try to notify the county
and get permission for a large quantity of caustic agents (batteries) and
get denied...Mix that in with a rooftop that can not pass the PE
Calculations for structural for lbs vs. sq foot and it's a no win situation
at MANY locations.

The FCC (US Goverment)is trying to appease some people (politicians)in feel
good legislation, nothing else. Just like laws that ban guns passing when
the 3 stike rule is not enforced it's just feel good words on paper, it
accomplishes NOTHING. They all get publicity and eventually the public
forget's about it till' the next big one. They hope that the next big one
does not come since they know this law CAN NOT be made valid and it will
never become reality. But in the meantime they have taken the heat off of
themselves for the time beeing after 9/11 and Katrina and hope no one
remembers what they said 10 years from now when it happens all over again
and find out that the law was never passed or just ignored.


-----Original Message-----
From: aprssig-bounces at lists.tapr.org
[mailto:aprssig-bounces at lists.tapr.org]On Behalf Of Scott Miller
Sent: Monday, March 17, 2008 2:25 PM
To: bruninga at usna.edu; TAPR APRS Mailing List
Subject: Re: [aprssig] 8 hour Backup Power Rule

Sounds like it's time to invest in battery and UPS manufacturers.  =]

Shouldn't we be planning for MORE than 8 hours if that's what the cell
phones are going to be held to?  Seems like we'd be most useful AFTER
backup power is out on the cell sites, at least if they ever do get that


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