From owner-qrp-l@Lehigh.EDU Tue Jan 20 12:41:31 1998 Received: from fidoii.CC.lehigh.EDU (fidoii.CC.lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.8.5/8.8.5) with ESMTP id MAA17019 for ; Tue, 20 Jan 1998 12:41:30 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.Lehigh.EDU with SMTP id <12835-18730>; Tue, 20 Jan 1998 12:40:46 -0500 Received: from nss4.cc.Lehigh.EDU ([128.180.1.13]) by fidoii.cc.Lehigh.EDU with ESMTP id <12506-33318>; Tue, 20 Jan 1998 12:38:02 -0500 Received: from server1.maxwell.com (server1b.maxwell.com [199.120.55.3]) by nss4.cc.Lehigh.EDU (8.8.8/8.8.5) with ESMTP id MAA62480 for ; Tue, 20 Jan 1998 12:38:00 -0500 Received: from inferno.scubed.com (inferno.scubed.com [192.31.66.42]) by server1.maxwell.com (8.8.7/8.7.2) with SMTP id JAA13642 for ; Tue, 20 Jan 1998 09:37:38 -0800 (PST) Received: from [192.31.66.158] by inferno.scubed.com (S3.4/s3-sgi-5) id RAA26199; Tue, 20 Jan 1998 17:30:50 GMT Message-Id: Date: Tue, 20 Jan 1998 10:40:04 -0700 Reply-To: ji3m@maxwell.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: ji3m@maxwell.com (James R. Duffey) To: "Low Power Amateur Radio Discussion" Subject: How I live with Deep Cycle Batteries Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: ji3m@192.31.66.42 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO The topic of using deep cycle batteries for Ham use comes up every so often here, and there are usually excellent replies, some of which have been posted recently. I thought I would give the practical side of using a deep cycle battery. When I got my first all solid state rig, a TS850SAT, nearly 4 years ago I didn't want to spring the extra $150 or so for a 20 A 13.6 VDC supply to run it. I bought a 110 AH marine deep cycle battery at Sam's Club for $45. I don't remember the brand name. I already had an ATEC 6 A "automatic charger" for automobile batteries. I put the battery in a trash sack in case of acid spills. For last years FYBO I bought a marine plastic battery holder (actually a case) which I now use. The whole thing fits out of sight in a file drawer of the old desk I use for my radio. I operate QRO (horrors!) about once a week for a SSB (more horrors!) sked with my dad. During this sked I plug in the battery charger and charge the battery while I have a chat with my dad. After the QSO I leave the charger on until the battery is "fully charged". In my shack, this state is defined by the charger cycling on and off, and a battery voltage reading of 14.2 volts or so. I then unplug the charger. I operate QRP the rest of the week on this charge, although for extended operating, like contests, I usually plug in the charger. Some times I monitor the voltage, but if I need the multimeter elsewhere that doesn't get done. Every once in a while I forget and leave the charger connected overnight. The charger reduces the charge "automatically" so I have not had problems so far. I suppose it would be OK to leave the charger on all the time, but I don't, mostly for "fear of falling off the edge of the earth." About once every 6 months I check the water level and top it off with distilled water if necessary. This combination has seen me through a 30 hour QRO Sweepstakes (before I got QRP religion). I fully charged the battery prior to the contest, and ran the charger continuously during the contest. There was a 6 hour rest period, of course, during which the battery saw charging, but no discharging. The battery was at 12 V at the end of the contest. I ran the TS850 QRP on the battery alone during last years FYBO with no problems. The battery alone will probably run the TS850AT for 48 hours or so of listening or QRP operation and 12 to 14 hours of QRO operation. That should be good enough for most emergency communications situations. If not, it can always be recharged with jumper cables and a car. Although I don't expect to have this combination last forever, it has done me well so far. Most sources I read rate the deep cycle batteries for 300 to 500 charge/ discharge cycles. As I rarely completely discharge the battery I probably have at least as much life left in the battery as I have used. Resist the temptation to use car batteries in this application. They are only good for 5 or 6 complete charge/discharge cycles and will need to be replaced more often. The deep discharge batteries are not that much more expensive than car batteries and are much better for this application. When I replace the current battery I will probably go to 2 - 6V deep discharge traction batteries designed for golf cart/fork lift use that can be obtained in 200 AH ratings. These are available at Sam's Club for not much more cost (each) than the 12 V deep cycle battery. The battery charger works OK, but runs hot. A thermal cutoff begins to activate after an hour or so of charging at the maximum rate. I keep intending to install a fan. Chargers such as mine can be found at flea markets or garage sales. If I were purchasing one today exclusively for this use, I would get a 10 Amp "automatic" charger. Then I could charge at the infamous C/10 rate. This would charge a bit faster and provide some more margin for QRO operation with the charger on. I notice that Sears sells one for $55. With a new battery this combination comes to about $100 for a 12V supply that also provides emergency communications. I don't think you can beat this for value. I keep intending to install a permanent voltmeter with expanded scale to monitor the battery condition, as well as an Ammeter in series with the rig. This hasn't gotten done yet, but it is on my "list". I have also looked into building my own charger, but with the availability of low cost automobile chargers this does not seem cost effective. One last caveat. Most "12V" gear is really optimized to operate on a fully charged battery which will give 13.6 V. Many rigs will not operate if the voltage drops much below 12 V, so it pays to use a fully charged battery. Unfortunately, most commercial rigs made today are not optimized for low power consumption. My 850 draws 2 A on receive. The older "microprocessorless" solid state rigs, as well as most QRP rigs, are much better in this respect. I try to treat the battery gently. I avoid deep discharges, I try to avoid charging longer than necessary, and I don't trickle charge. I speak gently to it, thanking it for providing me with power. I recommend the charger/deep discharge combination to those contemplating purchase of a 12 V supply. - Duffey KK6MC/5 James R Duffey KK6MC/5 DM65 30 Casa Loma Road Cedar Crest, NM 87008