John, There's nothing about a switching power supply that might disqualify it for battery float service. However, you should isolate the output of any power supply from the battery with a Schottky diode, so that a failure within the power supply- or the firing of the crowbar SCR- will not impose a dead short on the battery. After determining the correct float voltage for your battery plant, say, 14.2 VDC, set the output voltage of the power supply slightly higher to account for the small forward voltage drop of the Schottky diode. The load should be connected directly to the battery, not to the power supply.
I have several Astron switching power supplies in service, along with several similar units made by Duracomm and Samlex. They have all been extremely reliable, and the high switching frequency results in no perceptible buzz or ripple in the output. A decade ago, some switchers were poorly designed and radiated spurious signals into the HF bands, but none of the name-brand switchers produced today have that problem. In fact, Motorola uses Duracomm and Astec switching power supplies in most of its commercial repeater equipment. One thing to be aware of is that some Astron power supplies, both linear and switching, have an internal jumper that ties the negative output to chassis ground. This jumper must be removed to avoid some problems with ground loops and erratic controller functions. The presence of this jumper can be tested by measuring the DC resistance between the grounding prong of the AC power plug and the negative output terminal. If the resistance is above 10,000 ohms, you're good to go. Otherwise, you've got to get under the hood... 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of ab6li Sent: Monday, May 31, 2010 7:31 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Astron switching supply for Battery Charger?? Hello to the group. Has anyone used an Astron SS series switching supply for a battery float charger? I have seen the info on using the standard Astrons but I like the efficiency of the switcher. Any comments? Thanks in advance. John ab6li
