Patrick, All excellent points, and reality checks. Thanks for the feedback!
Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: "Patrick Shoemaker" <[email protected]> To: "WISPA General List" <[email protected]> Sent: Monday, August 03, 2009 5:58 PM Subject: Re: [WISPA] Small auto start generator >I think you'll find that to get a propane/NG generator installed on a > commercial building rooftop, you'll be looking at $10k minimum using > even the cheapest Generac air-cooled units. You'll need a roofing > company to come out and modify the roof to provide a mounting surface > for the generator, that will probably be the biggest cost. Getting > management comfortable with modifying a $300k roof membrane could be an > issue as well. Then getting gas to the unit from the building's gas > supply will require a plumbing contractor, permits, inspections. Then > the electrical hookup- more permits and inspections and a licensed EC. > > I just got a quote for qty 8 110AH 12v AGM batteries for a new site: > $1500 including shipping. > > A note on the Generac air-cooled generators. They break. All generators > break. The key is routine testing and PM. The generac air-cooled models > don't have any provision for automatic alarm reporting. So when a > battery dies or gas valve sticks or spark plug fouls or whatever, you > won't know about it until a manual site inspection or the power goes > out. The better generators (and the Generac liquid cooled models) have > contact closures or RS232 interfaces to report these conditions to your > site monitoring system, in turn notifying you back at the NOC. > > > Patrick Shoemaker > Vector Data Systems LLC > [email protected] > office: (301) 358-1690 x36 > http://www.vectordatasystems.com > > > Tom DeReggi wrote: >> We also use the triplite APS inverters with good quality Gel cell. >> Actually, >> we got a good 15 years out of the existing C&D batteries, because we >> inherited them from Teligent days :-) >> But new, qty 4- 12V 150AH batteries in series for about 3500watt and >> decent >> run-time is $1400. + $800 for replacement inverters. (The Triplites >> worked >> really well, but about half of them died by the end of eight years. We >> matched good inverters with good pre-existing batteries and vice versa.) >> So >> our thought was.... Why not buy a $2000 generator for the run-time and >> load, >> and then several smaller UPSes for infront to cover the surges, power >> conditioning, and monitoring? Ones that keep running even when batteries >> short out. Part of the reason we are investigating is that we now have >> duplicate need of devices to power. Some are AC devices like PC routers. >> Some are 20-24VDC w/AC adapters. Some are new licensed gear running on >> 48V. >> Cost is increased having long battery run time on both seperate AC and DC >> backup power subsystems. And how do we plan for load growth? How many new >> radios installed will be AC or DC? Unlicensed versus Licensed? We really >> dont know in advance. There is a lot of power waste going from AC to DC >> to >> AC to DC. >> >> The thought was... If long run time was accomplished by the propaine >> generator, both DC and AC battery subsystems could be installed with >> lower >> cost lower run-time batteries. We'd still need to account for max watts >> growth for each subsystem, but we could way reduce AH requirements for >> both >> subsystems. >> >> Or am I making this to complicated, and better just sticking with >> batteries >> :-) >> >> Chris Erikson's idea on solar panels sounded interesting. Although, I bet >> my >> ruthless roof rights people will try to charge me a monthly colo fee for >> them :-( >> I wonder if I can make the solar panels look like rain/weather shields >> :-) >> >> Tom DeReggi >> RapidDSL & Wireless, Inc >> IntAirNet- Fixed Wireless Broadband >> >> >> ----- Original Message ----- >> From: "jp" <[email protected]> >> To: "WISPA General List" <[email protected]> >> Sent: Monday, August 03, 2009 12:11 PM >> Subject: Re: [WISPA] Small auto start generator >> >> >>> The tripplite APS is what we use for this. Small generators are a pain. >>> >>> On Sun, Aug 02, 2009 at 02:57:23PM -0430, [email protected] wrote: >>>> You might want something like an inverter (Xantrex for example) which >>>> includes a DC to AC inverter, battery charger, and automatic transfer >>>> switch. Add the batteries and you're done. >>>> >>>> Greg >>>> >>>> On Aug 2, 2009, at 2:38 PM, Jerry Richardson wrote: >>>> >>>>> Thank you, >>>>> That is very good advice. After some research, I'm leaning toward a >>>>> UPS. >>>>> >>>>> A pair of good AGM batteries and charge controller will cost less >>>>> and be far less maintainence. Then I'd just run the CMM off the >>>>> batteries @ 24VDC. >>>>> >>>>> Thanks again >>>>> Jerry >>>>> >>>>> >>>>> -----Original Message----- >>>>> From: [email protected] [mailto:[email protected]] >>>>> On Behalf Of Gary Garrett >>>>> Sent: Sunday, August 02, 2009 11:59 AM >>>>> To: WISPA General List >>>>> Subject: Re: [WISPA] Small auto start generator >>>>> >>>>> Small generators do not auto start very reliably. >>>>> When cold or dampness causes hard starting the starter can overheat >>>>> and >>>>> burn out. Generally you need an electric choke to start gas engines, >>>>> propane can "flood" and need to rest before trying again, diesel can >>>>> be >>>>> REAL hard to start when cold. Auto starters can not adapt to changing >>>>> conditions. >>>>> Our best generator is a Propane Ford inline 6 cyl. 25 KW 3 phase. >>>>> (1955 >>>>> Model) >>>>> The monitor cranks for 1 min then rests and tries 3 times. >>>>> Everything is >>>>> adjustable. It knows to stop cranking when it sees AC voltage from the >>>>> Gen. so the motor over runs the starter for just a few seconds. Only a >>>>> huge starter motor can take this abuse and last unattended. >>>>> >>>>> You may be money ahead to find out why the existing generator is not >>>>> starting and get it fixed. >>>>> >>>>> Jerry Richardson wrote: >>>>>> We rent on a tower that is suspposed to have gen-set backup but it >>>>>> does not start reliably. >>>>>> >>>>>> Any recommendations on a small auto-start generator? We only need >>>>>> to power a CMMmicro - ~100watts. >>>>>> >>>>>> Thanks >>>>>> >>>>>> >>>>>> >>>>>> __________________________________ >>>>>> Jerry Richardson >>>>>> airCloud Communications >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> -------------------------------------------------------------------------------- >>>>>> WISPA Wants You! 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