Hi all,

Any recommendations for setting up a 12-volt battery backup for a ham radio base station (2m/70cm mobile), for use in the event of a power failure?

Thanks,
Lynn - KI6BRQ

The quickest and easiest thing to do is to get a large (depending on power demands of radio(s)) gell-cell battery and get a Power Gate. It will charge your battery and work as a switch if you loose power. This way uses more money but is quick & easy.

If you are able to solder and are ambitious, you can put together a charge controller from a kit or roll your own from scratch.

Hope this helps.

Matt had the easiest way - I have a 90Ah battery on float full time, ready to go, plus a bunch of smaller ones

I made friends with the guy who came out to service the REALLY BIG power backup (UPS) unit at work. He told me that his company replaces a battery after three years, just in case. He gave me one for free. It is 100 Ah, and I have it connected to a small solar panel. Works great. If you do get a used battery, be sure to check the date code (usually stamped into the top of the battery) and do a simple load test (attach an old headlight, and check for voltage drop over time). These batteries are also usually available at ham radio/electronic flea markets for $20 or so.

http://www.arrl.org/tis/info/emergency.html

The articles require ARRL membership to access; you can get your ID from your QST magazine mailing label. (If you're not an ARRL member, many libraries get QST so you can use this list to check back issues there.)

Dave F>

Thanks for the tip about the ARRL articles. I read all three, and it seems like installing a battery backup is pretty straight forward.

1. Get a deep-cycle 12 volt battery, preferably sealed (how many amp-hours?)

2. Attach a charger like a BatteryTender to the battery. I use one for my motorcycle. It's the kind you can leave on all the time without overcharging the battery.

3. Attach the power leads from the mobile radio to the battery.

Is it as simple as this?

73 - Lynn

My set up is a deep cycle marine battery, battery tender, Power Poles and a Rig Runner. I ran my IC706MKIIG for an entire Field Day weekend doing low power CW.

The powergate thing is an automatic switch, a good idea for unattended setups like repeaters, and for continuous operations that are hosed by even very short downtime. I think for base station use, the automatic switch isn't really needed. If the AC power goes out, you're off the air until you unplug your rig's AC power supply and connect up the battery supply, probably not a big deal even if takes a couple minutes. Anyway, yeah, deep discharge marine battery of gel cell with a trickle charger is the usual ticket. A fancy charge controller is overkill for this application. A battery friendly radio like most typical moviles seems like a good idea though.

It can be as simple as that. For the amp-hours I would not go below 20 x standby current. I also would select at least 5 x current at peak power (the one you want to actually use - not necessarily that of the rig). Less will result in voltage drops during transmission. For portable use I go lower but the voltage drops significantly during transmission. In portable use weight is an issue, for base stations it usually is not.
I also use two or three gel batteries. That way I have one in use, one on standby and one recharging (e. g. on a solar panel).
My base station is a Yaesu FT-7800 running on a 7.2 Ah lead gel battery.
I second going for the power poles. I liked them instantly. No male or female connectors and still right polarity can be encoded in a pair.

73 - Max