The size of supply you will need are dependent on several factors, such as peak current draw, average current draw, size of battery (in AH), and length of time to reach full charge, after an outage. Usually a single 35 or 50 amp supply will suffice, unless you are running high power or multiple repeaters, or some other type of load.
The Astrons really need to be modified (as pointed out below) to change the current limit point to a value that is at, or less than, the continuous duty rating. This can be readily accomplished by adding a single resistor, or a pot, to change the current limit to a lower point. If you don't do this, you could burn out the supply after a long outage, because the supply is running at full tilt for longer that it is designed for. We have used Astron supplies for many years supplying current to an 840 AH battery bank. Before we did the mod for the current limit (about 10 years ago), we did burn up a supply transformer, rectifiers, and transistors. Another thing to do is place a fuse between the Astron and the battery about 20-40% more than the continuous duty rating. This will protect the supply and the batteries from catastophic failure of each other. Joe --- Steve Grantham <[EMAIL PROTECTED]> 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 > > > [EMAIL PROTECTED] > > > > > > __________________________________ Do you Yahoo!? Yahoo! Mail Address AutoComplete - You start. We finish. http://promotions.yahoo.com/new_mail Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
