Substation Batteries 3

[musicguy1800]

The utility company I work for has several old lead-calcium substation batteries that are badly in need of replacement. I am doing some research to determine if there is another kind of battery that will provide a longer life and less maintenance. The manufacturer claimed that these batteries would last 10 years, but it was only three or four years before we started having problems. I have chosen to stick with wet-cell batteries for now, since using dry cells would require a change in our standards and practices.
One type of battery I am looking into is lead-selenium. Anyone familiar with this type of battery and its pros/cons? I have been told that there may be some environmental concerns. Also, any other type of wet cell (and manufacturer) that has proven to function well in your substation applications?

 

[dpc]

Lead-selinium batteries have been around for a long time and are just a variant of lead-acid batteries. I'm not aware of any issues that would be different in their application. Just as nasty as lead-calcium. I suspect any edition of the Electrical Engineer's Handbook will have more information.

Ni-Cad batteries are widely used in place of lead-acid batteries, although you will pay a premium. Lifetime can exceed lead-acid. Check Alcad website for more information. These still require periodic inspection and electrolyte level maintenance, although filling is seldom needed.

 

[busbar]

No offense is meant, but flooded lead-acid cells have fairly predictable life, provided they are properly specified, in the correct environment and routinely maintained. Without same, replacement battery sets will likely not do any better. Given the disastrous consequences of shortened battery life in breaker-tripping applications, you may want to stick to standard, well understood systems, and be certain of competent maintenance and monitoring. For ANSI regions, IEEE battery standards might be carefully reviewed and evaluated.

 

[jbartos]

Suggestion: Assuming that there is an existing dc power distribution system including switchboards, motor loads, valves, etc., the battery internal resistance (generally impedance) has to be kept in mind. Certain batteries have a high internal resistance, which would cause very large voltage dips or sags depending on nature of the load. Therefore, it may be a good idea to keep the battery the same or very similar, perhaps to search for a better quality battery manufacturer, if the existing power distribution system is to be properly utilized without requiring costly modifications. It is not unusual to have a short circuit current of the stationary lead-acid battery supply exceeding 20000ADC.

 

[alehman]

If your flooded cell lead acid batteries died after 3 or 4 years, it is likely they were some how mis-treated or cycled too much. I would expect 10 to 15 years. Flooded cell is far better than VRLA for reliability and ability to withstand abuse.

Flooded-cell NiCd batteries are considered by some to be more reliable, longer lived and lower in maintenance than lead-acid. NiCd is commonly used for swgr. There are disposal issues at end of life because cadmium is considered a hazardous waste.

 

[musicguy1800]

The lead-calcium batteries I am referring to are Liberty 1000 Series Lead Calcium batteries. We have installed them in several different locations, not just one, and in every location they have been installed in, they give us trouble. We own many substations with lead-acid batteries that are not Liberty's, and those batteries do just fine, lasting us at least 10 years and sometimes even 20. That's why I believe it is a manufacturer problem, not environmental.
I appreciate your helpful posts so far. Anyone else had trouble with Liberty 1000's?

 

[busbar]

‘Liberty 1000’ appears to be a valve-regalated {sealed} sort. In general, VRLA sets do not have the track record of the more traditional clear-jar flooded-cell variety.

 

[musicguy1800]

Are there different operating conditions or environment required for flooded cells vs. VRLA's? (e.g. ventilation, temperature, moisture)

 

[ScottyUK]

VRLA's are pretty much fit-and-forget batteries.

Plante cells need a fair amount of TLC to keep them in good condition: electrolyte level checks, electrolyte density checks, makeup fluids as required.

In theory VRLA's don't give off hydrogen during charging. If they are charged too rapidly, they vent hydrogen to the atmosphere. Plante cells evolve hydrogen routinely. I would treat both types as needing ventilation.

Plante cells are available in big sizes - 2V 2000AH being the biggest I've encountered, although I bet submarines use even bigger cells. VRLA's don't come this big.

 

[busbar]

The US Bureau of Reclamation has a terse comparison of Pb-Ca, Pb-Sb, and Pb-Se cells for stationary service.

http://www.usbr.gov/power/data/fist/fist3_6/fist3602.htm

http://www.usbr.gov/power/data/fist/fist3_6/3_6_cont.htm

 

[nukeman]

I do not agree with ScottyUK's description of "fit and forget". This is a misconception with VRLA's, you might not have to add water but but do have a lot of maintenance. IEEE 1188 provides all the recommended maintenance activities for VRLA's, not much different then IEEE 450 and in some cases more stringent (capacity test every year vs avery 5 years for lead-acid vented). If you have other vented cells that work why don't you install those in your application?

 

[musicguy1800]

The cells we have are not vented. They are VRLA's. They are also generally confined in spaces without much ventilation.

 

[dpc]

VRLA batteries have a bit of a tarnished reputation due to failure rates. Conventional wisdom is that traditional flooded cells are more reliable and have a longer life.

You might want to discuss necessary ventilation with battery suppliers. There is a lot of misinformation regarding ventilation requirements for lead-acid batteries. Some ventilation is required, but the necessary rate is not really terribly high. In many cases, we were able to achieve it through normal natural air flow without the need for forced ventilation. Most problems are created when batteries are jammed into a small "battery room". The smaller the space, the more ventilation required.

Ni-Cads might be another alternative. I don't believe they produce as much H2 as lead-acid batteries.

 

[Sargardani]

I didn't go through all the replies and therefore may repeat what some of the other members might already have said. The utility I worked for, some years back, had Lead Acid Batteries at one of the power plants which failed within the defect liability period (their plates started expanding and buckling etc). The supplier had to re supply batteries with Ca and they worked fine.
I would suggest to take up the matter with the supplier to see if the batteries are being operated according to their specs. If not they should suggest corrections. If there is nothing wrong with the operating conditions then the root cause of the early failure must be investigated.

I would recommend to check the internal resistance of the batteries and try to follow its trend right after commissioning.
Hope this helps %-)

 

[jghrist]

I agree with dpc and nukeman. I've heard VRLA referred to as "maintenance-proof" instead of "maintenance-free". They require as much or more maintenance, but you can't get to the electrolyte to check it.

 

[ScottyUK]

Nukeman and others,

'Fit and forget' was a poor choice of words on my part. What I was intended and failed to get across is that the routine checks on electrolyte level and SG, monthly at our plant, are not possible with VRLA's. IMHO, we spend a lot more time looking after our plante cells than our VRLA's, but in light of your comments I will check with the manufacturer to verify that we are not under-maintaining our VRLA batteries.

Annual discharge testing I totally agree with; our plante cells are getting old now, and the testing frequency has been increased. VRLA's are tested annually as you suggest.

I shall be more careful with my choice of phrase in future.

 

[musicguy1800]

Thanks for all the info. I will check with the manufacturers regarding ventilation considerations for flooded cell batteries and see if it is possible for us to switch over to those from our VRLA's. If you have anything else to add, don't hesitate to post, I am learning a lot here!

 

[alehman]

See also -
thread238-44411 thread238-82638 thread238-73268

http://www.powerbattery.com/acro-file/PQ2000.pdf

 

[jbartos]

Suggestion: A computer simulation or model of the new battery dc power distribution is prudent to have to avoid any inappropriate procurement of hardware.

 

[easnj]

When purchasing any battery pay attention to the warranty. If its a 10 year warranty with a pro rate after four years guess when you will start having failures. There are about 60 UPS in the network I work on, we have a lot Liberty Batteries out there and they are a good battery. After the four year mark there will be failures of VRLA batteries and between the 5 and 7 mark we change them out. Wet cells seem to be superior the VRLA for life expectancy. How did you treated the batteries i.e. charge rate, temperature etc. There is no 10 year string of VRLA batteries out there that requires no maintenance or cell replacement.