Just my opinion / experience : Optima Batteries as back up power source. I had purchased 5 new yellow top Optima batteries (deep cycle) for my home ham shack backup power system (thinking I was doing the smart thing). They were quite expensive. I've always believed 'you get what you pay for'. Honestly, I wish I would have never purchased them. They Suck! I previously had a single AC DELCO deep cycle family 27 sized battery prior, and it worked better under load then all 5 of these Optimas tied together. The Optimas I had purchased were all fresh (with a date code within the last month or two at the time). I ran these batteries on the same load as I had on the AC DELCO deep cycle battery, but the voltage on these yellow tops sinks faster than I can sneeze under any real load (yes, I'm exaggerating). Maybe the other ham is correct in stating that the Red Top starting battery is a better choice for this application.
Sometime later, while at a customers, I saw that they were using yellow topped Optimas inside of their black and white patrol fleet. Curious, I asked one of the mechanics from their maintenance garage how they liked them. He shook his head and stated that he didn't like them at all, but they are sealed, small, so that's just what we have to use when place batteries inside the vehicles. I then shared with him my experience, and he just kept nodding his head in agreement. I use to operate my HF station at 100W on the AC DELCO, and now with these five Optima yellow tops, I had to turn my HF stations output power down to 40 watts in order to sustain a QSO. I currently use and am very happy with four 6V 210AH AGM batteries. I just had to shoot this e-mail out before someone else made the same mistake I did, and a very expensive one at that. I would only use the yellow tops in an application where your running a base VHF/UHF radio at 5-10W. I have also since installed two 6V 210AH AGM batteries on an open UHF repeater that I am trustee of. And if your using old hand me down batteries on your repeaters / home stations, you get what you pay for. A friend of mine had me attach two (100lb) each deep cycle commercial batteries on his repeater up at one hill top site. Well after attaching them (with nice heavy gauge wire, all connections soldered), I pulled the AC plug to see how they'd handle the repeater. The batteries dropped down to 10 volts and the repeater started convulsing just 45 seconds into a solid key down of the transmitter. Also to mention is that these batteries had just been fully charged. In the past, I have also been handed 'hand me down batteries' (of different makes and models pulled from use). Some would only last two months before losing a cell and becoming useless. A friend of mine made a comment once about Optima batteries (which I have not verified) is that when an Optima is depleted, and re-charged, it will never fully recover. One must never let Optima batteries get below a specific voltage. So all in all, if you really want your equipment to actually work when all else fails . . . . Don't chance it, buy new, and choose wisely. Sure it will be expensive, but your buying a piece of mind. How much is that worth to you? As another note . . . Please do not tie a back-up battery directly across the main output terminals of a power supply (which provides no current limiting to the battery while re-charging). I have found this actually done at a hill top site. What had happened was that AC power to a repeater had been off for three days or so. The repeater was running exclusively off the battery for 3 days and finally depleted it. Well, when AC power was restored, the battery started pulling an enormous amount of amperes from the power supply (since it was now depleted). I was there at the time the AC was restored, and within a matter of a minute of the power being restored, I smelled something burning. After sniffing out it's point of origin in the room, I found that the power supply tied to the battery was too hot to touch, and that the wires connecting it to the battery were just about melting the insulation off. What a fire hazard. I disconnected that battery right then and there and notified the owner of the repeater. So please don't burn down our repeater sites. It's hard enough trying to get into commercial sites as it is. Many radio sites will never again accept an Amateur Radio station due to previous experiences with hams. Please don't add to that. Have Fun ! Paul Metzger - K6EH DVARA
