In the radio control airplane field, there are devices that get connected to a battery and will accurately measure the mAH capacity by discharging through a known resistance and periodically measuring the voltage. A calculation is done of the total mAH, then you will know if the battery is still good. Is there such a device for Canon camera batteries (like the BP-511A)?
"Telephone offices (back then, not sure about now) had huge battery back up systems & the batteries in some buildings were the size of smaller SUV's of today."
I hate to say it, but there systems that are a whole lot bigger than that. Like I said, I have seen entire floors of a skyscraper converted into one big battery room. The television studios in NYC are good examples of it. They have systems that can deliver three phases of 440 volts AC, with each phase delivering 1000 amps.
And, they can deliver that much power for up to 1 hour, which is just long enough for the emergency generators to kick in. They allow time for the primary generator to fail, until it rolls over to the secondary, until it rolls over to the stand-by. Those generators are huge engines. When they fail to start, they go through a 5 minute cycle that purges the fuel laden air that has built up inside of it. Three consecutive failures initiated a roll over to the next generator.
They wanted to be blackout proof, and keep their multiple satellite feeds on line. I've set them up before. Testing the systems are a challenge because knocking them off the air could cost the networks tens of thousands of dollars per minute, due to lost ad revenue. We literally watched TV and waited until a local commercial, like promoting the local news team, was broadcast.
Bell is a little different in that the systems were 48 Volt DC & like your systems they had generators as the first stage of back up & if they failed to keep up the batteries were next BUT if it went to the batteries mobile generators (Tractor Trailer mounted) were instantly on their way for additional back up. I have worked in their power bays (it's where they put me on day 1 for several months) & we had 80,000 Amp circuits. The power bays were all connected by 1/2 inch thick copper bars 4 inches wide & layered as needed to handle the amperage. We had to cover them up with special tarps whenever we worked is those areas & the rule was if you drop something don't reach for it. One guy dropped a 36 inch long wrench that turned into a very big spark when it fell but there wasn't a wrench left to hit the floor. Back then (60's) land lines were an essential service our government depended on & I worked in the building servicing the government several times.
The battery backups were just a stop gap, until the generators would kick in. I have seen some big ones in my time, with turbine driven air intakes. They literally had a jet engine driving the generator's turbine blades.
I have never done phones, but I have done high voltage radar in the 1970s. I have seen vacuum tubes the size of basketballs, and others which had to be water cooled in tanks of de-ionized water. The tanks were as big as a large refrigerator. The "coaxial cable" on the output was actually 36" pipe with a coaxial 18" conducting pipe inside of it. Output power to the antenna array was 5 megawatts.
That system was capable of detecting objects in low Earth orbits, up to 1000 miles in altitude. Today, we use satellites.
[EDIT] We once had a squirrel take a stroll on the output transformer one day. All that was left of it was a fluffy tail. Have you ever seen a plasma form between the plates of a vacuum tube before? I have. The plates were the size of a playing card, a couple of inches apart..
Oh, yeah. The main transmitter room for the radar was the size of basketball court. There were grounded copper sheets on the floor, like carpet runners, where you were supposed to walk when it was powered up. One day one of the output tubes, with the glowing plasma, failed. Lightning bolts were jumping out of the racks onto the copper flooring. It was a scene straight out of a James Bond movie; sparks, flames, and lightning bolts. It was my job to go in and shut it off. I used a wooden handled hammer to flip the four critical toggle switches.
That must have been "exciting"! Bet you didn't want to do that on a regular basis. Might have made a great video though.
Thanks everyone for the discussion so far. I asked the question, not about huge room-sized batteries, or even the battery packs that are used in r/c airplanes. This is about the 1000 to 2000 mAH battery used in the Canon cameras. A capacity tester is useful to determine if the battery is deteriorating. If one battery cost is $10 - $20, it would be worth it to have a tester in the $50 - $100 range, if you need a collection of batteries to keep your equipment running. I have seen articles on the internet about home-grown capacity testers along with discharge graphs that are produced, which clearly show the difference between a "weak" battery, and a "strong" battery, based on the shape of the discharge curve. You don't know how good a battery is, when you buy it. There is a large variation in the quality of the basic cells inside the pack. I was surprised to see, in the discharge curves, some batteries had only 1/3 the capacity they were labeled as!
I am just looking for a more scientific approach to this area, as opposed to just keeping a bagful of spares. If you are a member of a photography club, such a capacity tester could be shared among the members.
I'm in Canada & prices are higher than in the US but I think Europe is even higher but the charger I use wasn't too much over $100 when I bought it. The trick would be making the necessary adapters for the batteries since they don't come with lead wires & a plug. R/C batteries have both the balancing plug & the power plug but camera batteries in general have terminals set down into the protective case to prevent shorting out when there's metal (like a coin) in the same pocket the battery is. To date I've never seen adapters to do that & I follow several photography forums, BUT they may exist.
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