You already pointed out the major plus to A/C power: It's simple. Any joker can come along and plug something in. Almost every device has a 110VAC option.
UPS's are looking cheaper because you're getting used/refurb. You'll come out more comparable with a new DC system compared to a new UPS with similar runtime and capacity. I've never had a UPS as reliable as a rectifier. A handful of failures out of dozens over several years does not actually sound reliable at all. It's obviously tolerable to you in your scenario, but it's not telecom reliability. Scale that up to 100's of deployments and you'll be chasing dead UPS's more often than you'll want to. The good rectifier systems will be -48v because that's the standard for telecom power. If you're in Ubiquiti/Mikrotik land you'll have to use converters to +24V. If you're in Cisco/Juniper/Arista land then it can all be -48v and then you don't need the converters. I absolutely have been where you are now. If you're on a budget where what you can afford is the used APC XL then maybe you just stick with that. DC plant is better, but you will pay more for it and you'll pay more for the routers and switches designed for it. These are all statements of opinion, but it's opinion informed by 22 years of playing this game. -Adam -----Original Message----- From: AF <[email protected]> On Behalf Of Nate Burke Sent: Monday, June 28, 2021 12:58 PM To: Animal Farm <[email protected]> Subject: [AFMUG] Tower UPS's (again) We've been using the APC SmartUPS 750XL as a Tower UPS for several years. Put 2-8 100+AH AGM Batteries on them, and they've been rock solid for us. I can think of only a handful of failures in the dozens deployed over the last several years. I used to source them off ebay for $50-$70 each, but they're becoming more and more scarce. Anybody have a recommendation for a simple UPS that will do all the monitoring that the APC does and accept big batteries? We're a Metro-Rural Area, our power outages are usually measured in Hours, not days. So I'm not as concerned with the inefficiency of doing the DC/AC/DC Conversion for Runtime, just power stability during outages/fluctuations. I like the ease of connecting the external batteries to the APC, since the XL line has an Anderson plug on the back for them, and has a larger charger than the normal UPS, so recharge times are very quick. When the boss goes to the WISPA Shows, his head is filled with all kids of ideas, so he want's me to investigate doing everything as a DC Plant, When I price that out, with chargers, voltage converters (24/48), inverters, fuse protection, LVD, Monitoring, etc, it always seems like the price is a couple hundred dollars of parts and it would be cobbled together. Am I missing something with doing a DC Plant? I see the telco's at the sites using a rackmount rectifier with power supply modules, but those are a several hundred by themselves, and they are only 48V, they don't have to worry about 24v radios. When I build a site now, I drop in 2 batteries, and the APC, and the site is up and running in a couple minutes. A DIN rail with a couple power supplies and the box is done, and has fully monitored power, and I can plug in whatever I want without any equipment modifications. -- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com
