How do you check a standby battery?

7 Jun 2015
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United Kingdom
and checking the state of stand by battery

How do you do this? Does it require any additional kit like a charger /dummy load? Surely it's can't be as simple as just measuring the voltage, as the health of a lead acid battery is determined by it's storage capacity and not it's terminal voltage. The Yuasa test method seems to require hours of charging and some expensive digital kit. And a supply of thermal paper. What do you do?
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Connect it to a dummy load approx twice the normal in service load. Then over a period of time log the voltage, then plot the voltage time graph and from this the actual capacity of the battery can be estimated.
Its not as simple as just checking for 12 v at the battery?
Your could use a multimeter to check that that battery charging current is correct,but you need to put a load on the battery to check if will hold its charge.
We use drop tester in our industry.
Battery Test, it is different for different batteries, and different customers requirements, before the days of modern electronic exchanges, BT had hundreds of telephone exchanges all over in massive buildings full of banks of strowger electromechanical telephone switching equipment, cable tunnels, millions of pounds of investment and you can imagine any disruption to phone system could bring the whole communications network to a grinding halt, ours was the only company in 60s and 70s who were approved to by BT to service and install Fire Alarm System with automatic Co2 discharge system, such was their strict requirements that we did nothing other than BT work.

You can imagine they had massive banks of batteries to run their own equipment and in the event of mains power disruption, they had massive 20' high Diesel Generators and from time to time they ran them and they were also under the control of National grid to top up our grid during high demand, the amount of heat and fire risk was high, so early detection and prevention was on top of their list, in certain areas like in cable chambers, where thousands of thick bundles of cable from underground enter exchanges, had to have intrinsically safe systems, where we used suction tubes to analyse any combustible gasses, and raise an early warning, any spark could set the cable chambers and tunnels on fire, air extraction, and what not. So our Fire alarms had to be tested twice a year and batteries were subjected to 72Hrs standby and still be able to run a full alarm for another Hour minimum, we also had to use massive banks of 24v sealed lead acid batteries and change them every 5 years regardless of their state. This was BT's requirement. We met all their specifications and so were the only approved contractor.

BT did not rely on simulated tests, they only accepted real mains failure test lasting 72hours and then tested the system to ensure that batteries still had enough capacity to trigger solenoids to trip C02 high pressure gas cylinders, for flooding certain critical areas, sprinkler control, these battery tests were carried during certain bank holiday periods when most of the offices were closed and on holidays and London exchange would be closed and not too much telephone traffic., in between they conducted weekly tests.

How it is done today, and who by, I have no idea as we stopped installing and servicing their equipment in mid 90s when intelligent fire alarm panels started to flood the market and many new companies had entered the market, Bt themselves were upgrading their strowger systems to modern electronic system where instead of a whole building they only needed one large room to house computerised systems, Many of their old exchanges are now offices, I remember when they first had so called System X, had no idea then what that meant, it was at Baynard house in london, a huge building that also has a BT Museum in London by Thames,. we had about 20 fire alarm control panels in that building alone all linked with one another, with ability to control c02 flooding, fume and gas extraction, fire door control, evacuation control, repeater panels to show where fire originated, and so on, we were kept very busy then, I left that company in 1992, and set up my own business in an EAS industry.

We made sure that our battery capacity to run the entire system was 50% more than required to be on a safe side, all our chargers were fully monitored, and relied on charge pulse analising, if a charge pulse was not being absorbed as per good batteries, a fault alarm would be raised, the pulse would collapse partially if one of the cells in the battery became faulty, or stretch in amplitude if the charge rate suffered due to batteries not absorbing the charge.

It was almost like protecting a nuclear power station.
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