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! 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/
