RE: [Repeater-Builder] Battery system for portable repeater (non solar)
At 12:47 PM 01/30/10, you wrote: Hi Mike, We're using a Kenwood TKR-720. The price was right (we had it on hand), it's relatively compact, does what we need it to. Older technology, with the front panel controller, etc. You know of a way to reduce the current?Did remove the + from the audio amp got it down to 300ma, but also removed a voltage for the xmit control - could fix, but I think it would require the removal of the logic board to get at the traces. I'll have to dig up a manual and look at the schematics... Understand about the generator, but that's one more 'messy' thing to check on our monthly checks, bad gas, gummy gas, carb problems, fuel leaks, etc. I know they have spark arrestors, but I can see us putting this thing on the side of a hill, and having some wild hog come along knock it over, putting the exhaust right on flammable grass, etc! Understand about that... The situation where we used a small battery and a generator was for a portable repeater and the repeater was going to be manned... we packed it in, set it up, and one person camped for the duration, then we rode in, took it down and packed out. As such having that person watch the digital voltmeter and the transmit running time meter and run the generator for a half hour every couple of hours wasn't a problem. That was an interesting article on a build it yourself alternator/charging system. Yep. That's why I posted it. Might give someone an idea on how to use some leftover junque. (junk=trash junque=high grade useful trash) Just remember that the ripple reduction depends on the battery - one with a high internal ESR will not be very effective. A friend built a similar unit based on the June 1997 QST article and ended up adding alternator whine filters to the design (no, he didn't have one bad diode in the alternator). That battery tender looks like it might fill the bill.. I'll check it out. They are not cheap, but they seem to work. There is a chain of stores called Batteries Plus and there may be one in your area. They stock them. Some True Value and Ace hardware stores also stock them. Thanks again, Tim Mike WA6ILQ
RE: [Repeater-Builder] Battery system for portable repeater (non solar)
At 09:24 PM 01/29/10, you wrote: I'll look into the AGM bats - the rptr draws about 450 mA in RX, and about 4A in TX. What do you have in that portable repeater that draws almost half an amp in receive? Getting a Pelican case for the repeater cables, but not sure how to make the battery transportable.. Wheels?? I'd take a heavy duty trash cart, torch off the axle and the 4 inch wheels, move the axle up on the frame so that some 12-inch or 14-inch wheels fit, then put the battery box on that. I suppose if it's 'really' sealed, then I wouldn't have to worry about leakage of the electrolyte - could use a case for it the charger. I was involved in a similar but different situation a few years ago. I was looking at transporting eight 12v 18ah batteries, a GR300 repeater, four 10-foot sections of antenna mast, the antenna itself and some coax, about 12 miles, all by horseback. Why the 18ah batteries? They were available, and new. One of the club members needed to re-battery four UPS units where he worked. Each used two of those batteries in series. He had planned the re-batterying such that he'd buy the eight a few days previous to the race, charge them, use them over the weekend as a single parallel bank of almost 150ah, then install them in the UPSs the week after the race. Then it was pointed out that a single battery (to smooth the juice), a small Honda generator (the current model is here - see http://www.hondapowerequipment.com/products/modeldetail.aspx?page=modeldetailsection=P2GGmodelname=EU1000Imodelid=EU1000IAN and some gasoline (at 6 pounds to the gallon) weighs a lot less for the same delivered amp-hours, and has charging ability as a bonus. This one is lots cheaper, won't last as long, and is more fuel hungry (you get what you pay for): http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=66619 For a roll-your-own version, this might be interesting... http://www.thefoodguys.com/homemadepower.htm Any recommendations about appropriate 'sure-fire' chargers for one of these? Ask the guys that have been doing long-life batteries, and professional charging systems for over a century... the phone company. Unless I'm mistaken the Eagle Rock central office here in Los Angeles is still using the 1939 glass Edison cell battery plant. I could put together something for float charging, Look at the Battery Tender products (made by Deltran) for maintenance charging. A while back I installed one under the hood of a friends car that gets used maybe once every 4 to 6 months. See http://batterytender.com/automotive/waterproof-800-usa-western-hemisphere.html There is probably something better out there but that scratched the owners itch. but there will also be a need for 'real' charging as well. As I said, ask a retired telco plant engineer for some ideas. Thanks again, Tim Mike WA6ILQ
RE: [Repeater-Builder] Battery system for portable repeater (non solar)
Hi Mike, We're using a Kenwood TKR-720. The price was right (we had it on hand), it's relatively compact, does what we need it to. Older technology, with the front panel controller, etc. You know of a way to reduce the current?Did remove the + from the audio amp got it down to 300ma, but also removed a voltage for the xmit control - could fix, but I think it would require the removal of the logic board to get at the traces. Understand about the generator, but that's one more 'messy' thing to check on our monthly checks, bad gas, gummy gas, carb problems, fuel leaks, etc. I know they have spark arrestors, but I can see us putting this thing on the side of a hill, and having some wild hog come along knock it over, putting the exhaust right on flammable grass, etc! That was an interesting article on a build it yourself alternator/charging system. That battery tender looks like it might fill the bill.. I'll check it out. Thanks again, Tim
RE: [Repeater-Builder] Battery system for portable repeater (non solar)
When you have this repeater active what is it's duty cycle going to be? Also are you just going to use the truck to get it to the top of the hill and then drop off the package and retrieve it later? If this is the case have you thought about putting all of this on a trailer with a small crankup tower to extend the antenna a little higher up and then you could mount solar panels to the unit and charge/recharge the batteries all the time. Stan --- On Sat, 1/30/10, Tim Ahrens tahr...@swtexas.net wrote: From: Tim Ahrens tahr...@swtexas.net Subject: RE: [Repeater-Builder] Battery system for portable repeater (non solar) To: Repeater-Builder@yahoogroups.com Date: Saturday, January 30, 2010, 2:47 PM Hi Mike, We're using a Kenwood TKR-720. The price was right (we had it on hand), it's relatively compact, does what we need it to. Older technology, with the front panel controller, etc. You know of a way to reduce the current? Did remove the + from the audio amp got it down to 300ma, but also removed a voltage for the xmit control - could fix, but I think it would require the removal of the logic board to get at the traces. Understand about the generator, but that's one more 'messy' thing to check on our monthly checks, bad gas, gummy gas, carb problems, fuel leaks, etc. I know they have spark arrestors, but I can see us putting this thing on the side of a hill, and having some wild hog come along knock it over, putting the exhaust right on flammable grass, etc! That was an interesting article on a build it yourself alternator/charging system. That battery tender looks like it might fill the bill.. I'll check it out. Thanks again, Tim
RE: [Repeater-Builder] Battery system for portable repeater (non solar)
Tim, The ideal battery that will not boil off electrolyte is a VRSLA (Valve Regulated Sealed Lead Acid) unit with AGM (Absorptive Glass Mat) design. Provided that the charging voltage remains within the tolerances specified by the battery manufacturer, it will never run dry. That's because the hydrogen and oxygen generated during charging are recombined by catalysts within the battery, so that pressure cannot build up and vent. Such batteries are usually identified as non-spillable since the electrolyte is in gelled form rather than liquid form. One question: Are you using a different PL tone on the portable repeater, so that you don't key up both machines when you're in a coverage overlap area? 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tahrens301 Sent: Friday, January 29, 2010 4:00 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Battery system for portable repeater (non solar) Now that the actual repeater is complete, I am looking for some suggestions about how to power it. The repeater and +12v power source will be stored in our rescue truck. The idea behind this is to be able to set it up on top of a hill so that we can have communications with personnel on the other side. (although we have a pretty good 'main' repeater, there are many areas of our district where we don't have handheld coverage). There won't be any charging while at the operating site - a fresh battery will be brought in as required, or it could possibly be powered by a vehicle. Ideally, I'd like to store the power source on the truck with a trickle charger to keep it ready to go, but I'm concerned about gas. Do the AGM style batteries outgas while charging? From what I've read about backup power, the AGM is the most 'forgiving' for really deep cycling. Just not sure about leaving a trickle charger going all the time. (bad previous experiences) Thanks, Tim
