Back to Home   Backup and Alternative Power Projects, Articles and Reference Material
Maintained by Robert Meister WA1MIK

The information presented on this web page is copyrighted by the original author / provider (i.e. APC, Falcon Electric, the ARRL (QST)). Other information is copyright by (the author's copyright, if any, supercedes it).

This page contains articles related to alternative and backup power systems, such as Uninterruptable Power Supplies (UPSes), Battery Backups (BB), Photo-Voltaic (PV), and other sources of energy besides the regular commercial (mains) power.

Repeater-Builder welcomes articles about implementation and modification of such systems.

Background Information:

AC Power Information - Safety Issues when dealing with commercial AC power   by Mike Morris WA6ILQ
This is here just because Backup and alternative power systems run at high voltage levels. This article covers a few safety topics, like "the black wire can kill you".
A chart of non-locking electrical connectors used in the USA   480 kB PDF; published by Qualtek
NEMA is organization that designs the connectors, and yes, there is a reason for each one.
A chart of locking (twist-lock) electrical connectors used in the USA   590 kB PDF; published by Qualtek
Yet another NEMA connector chart.
12V 18AH battery datasheet   1.4 MB PDF; published by Power-Sonic/Panasonic
In all my years of buying UPS batteries, I've never gotten a datasheet with them. And who pays list price these days? Not me. The "Charging" section on page 2 is worth reading if you want to maximize battery life. Don't just install them in the UPS.

UPS-related Information:

UPS Technologies   An explanation of the major UPS technologies, common power problems, and information about choosing the right unit to solve them. Summarized from information on the web.
Testing the switching time of UPS units   By Robert W. Meister WA1MIK
Some units switch from mains power to the inverter faster than others. The author ran some tests and captured some waveforms from a couple of common UPS models.
Modifying an APC SU1000 for extended run-time   By Robert W. Meister WA1MIK
The run-time of a UPS is directly related to the battery capacity. It's relatively easy to install larger batteries in a lot of the different APC units (a SU1000 model is shown). This article shows you how to do it.
One manufacturer's explanation of various standby and UPS power systems   Off-site link to their article.
The SBS and UPS tutorial   from Falcon Electric
Great explanation of the various technologies. 242 kB PDF file.
On-Line UPS Block Diagram   from Liebert's GXT2 On-line UPS Owner's Manual
Probably typical of the true on-line units. 206 kB PDF file.
APC Corp Application Note #12, The APC Computer Interface Port   140 kB PDF
"This application note provides technical information regarding APC UPS computer interface ports. This information is for customers attempting to use the port for unsupported purposes."
Note that this is for the units that have a female DB-9 connector on the back. With the information from this applications note you can interface digital inputs on your repeater controller and detect the presence of AC power, etc.
Generators and UPS Compatibility   Technical information from Cummins. 550 kB PDF file.
This white paper discusses problems that can be encountered in operating UPS equipment on generator sets, explains the reasons behind some problems, and identifies steps that can be taken to minimize compatibility problems between generator sets and UPS equipment.

Alternative Power-related Articles and Information:

Exercise those backup batteries regularly   by George Odom K4ETN
Periodically disconnect AC power to exercise your battery backup systems.
Solar Power for Your Ham Station   A reprint of an article from QST April 1996. 186 kB PDF file.
Solar Charge Controller   An article from Home Power Magazine, Issue #63 (Feb/Mar 1998). 330 kB PDF file.
Storage Battery Maintenance and Principles   A reprint of an article published by the Department of the Interior, Bureau of Reclamation, December 1997. 1.2MB PDF file.
Practical Battery Back-Up for Amateur Radio Stations - Part 1   from QST March 1990, by George Thurston W4MLE (SK)   1.16 MB PDF
Despite it being over 20 years old this three-part article is well worth reading for the background info and overall theory.
Practical Battery Back-Up for Amateur Radio Stations - Part 2   from QST April 1990. 1.5 MB PDF file.
Practical Battery Back-Up for Amateur Radio Stations - Part 3   from QST May 1990. 1.0 MB PDF file.
Practical Battery Back-Up for Amateur Radio Stations - all three parts as a single file   from QST for March, April and May 1990. 3.7 MB PDF file.
Low-Voltage Battery Disconnect   An article from Home Power Magazine, Issue #60 (Aug/Sep 1997). 200 kB PDF file.
A Battery Voltage Monitor   By Ronald Varner WB3CEH from QST for October 1998   673 kB PDF
A simple 1-chip circuit with an adjustable threshold.
A Latching Low Voltage Disconnect   By Sam Ulbing, N4UAU from QST for June 1999   183 kB PDF
The latching circuit is attractive since the circuit in the article above has a flaw: no hysteresis. Every time the low voltage disconnect triggered it disconnects the load, and the battery voltage rises and the circuit would reconnect the load. Depending on the battery capacity, the battery state of charge, the draw of the load, etc. the disconnect circuit switches the load on and off at a rate of 1 to 2 cycles per minute.
Sealed Lead Acid Battery Charger   by Luke Enriquez VK3EM.
An Automatic Sealed-Lead-Acid Battery Charger   By Bob Lewis AA4PB from QST for May 2001   136 kB PDF
This is a clever little charger that not only charges your batteries, but can keep them on trickle charge safely.
The Micro M+ Charge Controller   By Mike Bryce WB8VGE   289 kB PDF
This unit is an excellent small (4 Amps max) solar panel charge controller for charging gel cells or just about any lead acid battery. It has a standby current of under 1 mA.
The 12-volt Pup   By Yaniko Palis VE2NYP from QST for June 1970   385 kB PDF
A 12V dc Boost Regulator for Battery Operation   By Daniel Kemppainen N8XJK from QST for November 2004   610 kB PDF
Those NiCad Batteries and How to Charge Them   By David W. Potter W2GZD from QST for October 1981   162 kB PDF
High efficiency lead-acid battery charger using power components   By Vicor Corporation   131 kB PDF
Ni-MH Battery Handbook   By Panasonic Corporation   3.7 MB PDF
Reader comments about batteries   Compiled by Mike Morris WA6ILQ
Discussions on various battery technologies and war stories.

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This page originally posted 23-Dec-2007.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.