Station Battery Load Testing 3

[dpc]

Another thread on battery conductance testing prompts me to ask a related question regarding periodic battery load testing. I believe the NETA standards recommend a dc load test every two years. Some testing companies are telling us that load tests are not commonly done any longer as part of maintenance testing.

I was skeptical, so I checked with a large regional electric utility and was told that they no longer do routine load tests on substation batteries because they believe it can shorten battery life.

I'd be interested in hearing what others are doing.

Thanks,

Dave

 

[Zogzog]

There has been some debates on this as of late, I think it is driven by manufactures of battery testing equipment, some say an impedence test is as good as a load test. IEEE 450 disagrees, they still recommend a load test last time I checked.

 

[TurbineGen]

The power utility I worked for stopped doing load tests on it's batteries for two reasons: 1. Load testing supposedly shortens battery life, and 2. The testing costs half the price of a new battery bank because they always hired a contractor to do the work. So now they just replace them every 8 or so years. They still monitor voltage and do an electrolyte check periodically.

I have heard the same rumors about load testing shortening the life of the batteries, but I am hesitant to believe it. In the reports on the batteries at our power stations, I saw no difference in lifespan between the stations that did load testing and those that did not.

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If it is broken, fix it. If it isn't broken, I'll soon fix that.

 

[ScottyUK]

The site I recently left was still doing discharge tests. I suspect the insurers, being a very conservative bunch, might demand battery discharge test results in the event of a battery failure and a claim being made. Capacity did not appear to degrade abnormally over the ten or so years we were testing while I was there.

Anyone from the insurers on this site who might be able to comment?


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If we learn from our mistakes I'm getting a great education!

 

[oldfieldguy]

I don't have the docs here, but load testing for flooded-cell batteries every five years was an IEEE standard...

Do the advances in battery testing apparatus negate the need for real load tests?

old field guy

 

[dpc]

I've found that testing recommendations often have at least some correlation to the expensive testing gear that someone happens to own.

I thought NETA recommended every two years, but I was going from memory - five years seems more reasonable, actually.

 

[Zogzog]

"I thought NETA recommended every two years, but I was going from memory - five years seems more reasonable, actually."

NETA testing intervals are based on the NFPA 70B and then factor in reliablilty requirements and environmental conditions, so there is no set time. I agree that every 5 years is resonable unless the owner has had problems or there are special conditions.

 

[mgtrp]

My former utility generally ran two battery banks per generating station, and did a discharge test on one of the two banks each year. Generally batteries were 12V 10-year life sealed gel type, and we certainly saw enough individual blocks fail in 5-10 year age group to warrant the testing more frequently than every 5 years.

Perhaps test frequency should be increased as the battery ages?

 

[Zogzog]

"Perhaps test frequency should be increased as the battery ages? "

Just like us older guys going to the doc more often, not a bad idea.

 

[alehman]

I don't think discharge testing flooded type batteries is a particularly harmful if you don't do it every week. Discharge testing is still by far the most reliable diagnostic. I don't recall IEEE 450 recommending conductance tests. That test was invented primarily for VRLA cells.

VRLA types are another story. I'd do a full discharge test when they are new and maybe after one or two years, but that's about it. I would do a conductance test or short load test every six months because they have a way of failing suddenly and unpredictably.