The simplest way is just to get the IOTA supply and float it across the battery. Thats it, nothing else needed. Get an IOTA big enough to power whatever you have, and still have some left over for charging. You don't need (or want) diodes, resistors, or relays.
It shouldn't be that easy, but in this case it is. I have some commercial sites that we run this way without problems. We have some with big Astron supplies, but we are changing them out to the IOTA. The new supplies will pay for themselves in a couple of years due to higher efficiency over the linear Astrons. The Astrons will also work well, with very minor mods. You still don't need the diodes. We have used the Astrons for over 12 years this way, the IOTAs for about 2.5 . Joe --- Richard <[EMAIL PROTECTED]> wrote: > I had a similar experience: I had a couple of deep > cycle batteries in an > outdoor steel enclosure that I would charge > periodically by connecting a > standard automotive charger. At times I would forget > it was connected, so > eventually the batteries were cooked. After some > research on the web, I > settled on an IOTA DLS-15 power supply with an IQ4 > smart charge controller. > It is connected full time to the (new) batteries, > and I only have to add > water every couple of months. I have not noted any > kind of noise generated > by the charger. This setup works very well for me. > > Richard, N7TGB > > > -----Original Message----- > From: Repeater-Builder@yahoogroups.com > [mailto:[EMAIL PROTECTED] Behalf > Of Dave Schmidt > Sent: Tuesday, January 09, 2007 9:26 AM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Re: Battery backup > > > > I have to agree with Dave. Using the proper > charger or power supply for > keeping the batts up. I have my batteries housed in > a stainless steel > enclosure that is anchored into concrete outside my > ham shack. I learned the > hard way about using the proper charger... I just > tapped into my repeaters > 25amp power supply to keep the batteries charged > till I could make a > charging circuit ... ahhhh, big mistake. That > charging circuit - oops, I > forgot... about a month of operation, I was working > around the tower and > smelled what smelled like battery acid. Sure enough, > I cooked both flooded > lead acid batteries and they were fuming acid vapor. > Lucky the box is a > comercial built ss box. > > Now, after that incident, I have been using a > marine (boat) "smart > charger" which automatically determines wether to > charge or float. Since > battery chargers are, ummm, quite noisy and not all > that nice on batteries > due to most of them only using a half wave recifier > ( AC is not nice on > batteries ). I added a 25A bridge rectifier and > added extra filtering which > is just a big Motorola mobile power filter block > from the Micor dayz. It is > also isolated using some BIG diodes - like Dave's, > the threaded case type > diodes which is bolted to a heatsink. > > The system is running well in this configuration. > If using flooded type > batteries, do a monthly check on acid levels ! I > recomend AGM batteries > ( Absorbed Glass Mat ) or if that is a little pricy, > get marine deep cycle > batteries - do not use automotive batteries unless > you just absolutely half > to. > > Dave / N9NLU > www.kmcg.org > > > > > > > > On 1/9/07, ve7ltd <[EMAIL PROTECTED]> wrote: > I have had good luck using a pair of diodes to > isolate a power supply > from a charging circuit. I essentially have a > Statpower 10amp battery > charger (specifically designed for the flooded > cells I am using). The > batteries float on the charger voltage when the > AC power is available. > The battery positive lead then feeds through a > diode and joins > the "positive power bus" of my repeaters. Using > a proper charger is the > most important part so you dont boil off the > electrolyte in your > batteries. > > The positive power bus is fed from a large GE > power supply. The > positive lead from the power supply feeds > through a diode to feed the > power bus. > > The idea of using a diodes is to keep the higher > voltage of the power > supply from passing current into the batteries > when AC is available, > and vice versa when AC is off. > > However, if you are using a high power PA or > your repeater draws more > than about 20 AMPs on TX, you have to be careful > of your choices of > diode. I use large feedthrough diodes, mounted > on large heatsinks, but > on lower current draw you could get away with > using a smaller bridge > rectifier mounted to an unpainted metal piece in > your repeater cabinet > with some heatsink compound. > > Dave Cameron > VE7LTD > > --- In Repeater-Builder@yahoogroups.com, "wm5c" > <[EMAIL PROTECTED]> > wrote: > > > > Hi, > > > > New member here. Thanks for allowing me to > join. > > Our club has acquired some large lead-acid 12v > batteries we would > like > > to use to back up our repeater in emergency > situations. Does anyone > > know of a good (but simple and inexpensive [we > are a very small group > > in a very small town]) circuit to accomplish > this? Any input would > be > > appreciated. > > > > Danny WM5C > > Heart Of Texas Ham Operators Group (HOTHOG) > > Brady, TX > > www.hothog.org > > > > > > > > > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! 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