There are extremely nice battery chargers well suited for applications like repeaters. I have used two from a company called XANTREX. I have an older model that I use in my communication van to charge two batteries (it has dual outputs). The one I use with one of my repeaters is the true charge 20i. The true charge 20i can source 20A continuous. It provides a float voltage normally and its voltage can be temperature comensated while in float. There are settings for "gel cell" and normal lead acid batteries. The charger provides a slightly higher voltage (open-circuit voltage)when bringing back a discharged battery much like an suto system. A microprocessor controls the timing of the charge cycle. I get much better life of the backup batteries with this charge system than I got with standard chargers. These are built for marine apps and are pretty rugged. There are many other brands. This model, while PWM based, seems pretty quite. I have a TS440 remote base running from the battery which does not hear any PWM hash.
Your mileage may vary Good Luck es 73 Ed K3SWJ --- In [email protected], Steve Rodgers <[EMAIL PROTECTED]> wrote: > What you need is not a power supply, but a battery charger. As I mentioned > in my prior post, you need to have a way to set the current limit so that > you don't overload the power supply. Battery chargers are designed to > do this. Also you need to make sure the terminal charge voltage on the battery > charger is set correctly (usually 13.65V for lead/acid battery tech). > > Another problem with the Astron is that you risk blowing out the voltage > regulator if AC power is lost and power is back-fed into the power supply > from the battery system. If you want to use an Astron supply to charge > your batteries, get a large schottky diode and put it in series with the > + output to protect the supply, then adjust the output voltage of the supply > to compensate. As mentioned earlier you will still need to lower the current > limit on a larger Astron supply such as the RM-60M and RS-70M as the battery > will draw the maximum current all the way to the foldback limit of the power > supply. > > > Steve > WA6ZFT > > > > On Sunday 26 September 2004 22:09, Steve Grantham wrote: > > Well... I have noticed that there are some RS-35M's out there that are > > "heavier-duty" than others. I have one with a heavier heatsink, larger > > xfmr, stud-type SCR, and an extra filter cap. I guess they must have > > started making them cheaper since... > > > > I am running a 40 Amp charge controller. Therefore, I believe I need a PS > > that will run cool and current limit at 35 or 40 Amps so I can get out of > > current limiting faster when recovering from a state of discharge after an > > AC power failure. Which model(s) would that fit? (Time to go search the > > web...) > > > > Steve > > AA5SG > > > > ----- Original Message ----- > > From: "Steve Rodgers" <[EMAIL PROTECTED]> > > To: <[email protected]> > > Sent: Sunday, September 26, 2004 10:39 PM > > Subject: Re: [Repeater-Builder] BIG battery & Astron current limit > > > > > One thinkng I forgot to mention: Batteries should be charged from a > > > > current > > > > > source. What this means is the maximum charge current should be limited > > > to protect the power supply. I would call Astron and ask them how to > > > modify > > > > the > > > > > RM35M so it starts folding back at 15A instead of its default of 35A. > > > Your power supply will thank you for it. > > > > > > Steve > > > WA6ZFT > > > > > > On Sunday 26 September 2004 20:20, Steve Rodgers wrote: > > > > The question should be how long before the Astron RS-35M burns up > > > > running > > > > > > at 34A? The power supply is rated for 25A continuous duty, 35A > > > > intermittent > > > > > > duty. I don't like running mine north of 15A continuous without a fan. > > > > This is the weakness with the Astron supplies. If you load them up to > > > > rated > > > > > > output they run very hot. If you are planning on running 35A > > > > continuous, I'd get an RM-60 or an RS-70. > > > > > > > > Steve > > > > WA6ZFT > > > > > > > > On Sunday 26 September 2004 20:01, Steve Grantham wrote: > > > > > How long would the RS-35M run in current limit at 34 Amps? (This is > > > > > about 97%.) > > > > > > > > > > I have noticed that the internal ammeter sometimes lacks good > > > > > calibration. As measured on a quality manufactured shunt, 34 Amps > > > > > pegs out the panel ammeter on the RS-35M, which indicates 40 Amps > > > > > Max. > > > > > > > > > > Anyone have experience with this? > > > > > > > > > > Steve > > > > > AA5SG > > > > > > ---------------------------------------------------------------- --------- > > > > > > > >-- ----- > > > > > > > > > > The below quoted from: > > > > > http://www.repeater-builder.com/astron/astron- rsbattmod.html A couple > > > > of > > > > > > > additional comments presented by Joe Montierth .... > > > > > One, the 10K resistor can be 1/4 watt or even 1/8 watt, the 1/2 watt > > > > is > > > > > > > overkill. There is not much voltage across it to generate any heat. > > > > > > > > > > Two, depending on the size battery it is attached to, you might want > > > > to > > > > > > > reduce the current limit point on the Astron. The 35 amp Astron will > > > > > current limit somewhat above the 35 amp point, maybe around 37-39 > > > > amps. > > > > > > > If you have it attached to a BIG battery, it can run several hours at > > > > the > > > > > > > current limit, and burn itself out. If you parallel R4 with a 1K pot, > > > > you > > > > > > > can adjust the current limit to a point less than 38 amps, usually > > > > about > > > > > > > 70-80% of the power supply rating is good. > > > > > > > > > > Three, always turn the PS "on" before attaching it to the battery. > > > > This > > > > > > > will keep the internal caps charged up, so they don't have to > > > > > suddenly charge through the pass transistors on the Astron. > > > > > > > > Yahoo! Groups Links > > > > > > Yahoo! Groups Links > > > > Yahoo! Groups Links > > > > > > Yahoo! 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