Battery Discharge Test. Is it Harmful to the Battery Life?

Look at it this way. The battery will last at least two years.

industrial batter will last more than 10 years. I am still searching for literature explaning about effect of battery discharge test effect on battery life/

Yes. You are right Mr SimpleMind. I am working in power station. We have both lead acid and alkaline battery. As you point out, as long as we monitor the voltage, and the voltage maintain above the recommendation by OEM it should be fine right. Furthermore, the battery system function should be able to protect the protected system which is turbine etc. If a few battery cell fail, we just replace it. Not worth to save a battery which cost only a portion of the damage when it fail to work when needed. Thanks for your respond. I will relay this to my colleague. Awaiting other input and experience sharing. Thank you

Regards,

Shah

I believe, marine communication emergency power supply batteries were required to be tested this way.

A critical point of doing a battery discharge test is to identify a failing battery before it is needed. Let's not forget this important aspect.

I agree that stopping the discharge before reaching the manufacturer's recommended minimum voltage should not significantly alter the lifetime of the battery.

my next question. How often do you carry out discharge test. Currently at my plant,

we carry out discharge test every 2 years. Is there any standard out there for this test? thank you.

In merchant navy, battery capacity tests of emergency communication equipments are mandatory, every two years.

...and if it does, then the battery needs replacement, which is, after all, the point of the test.

In a lead-acid battery plant like yours there are monhtly maintenance tasks to be performed: checking the torque on the terminals, measuring specific gravity in the individual cells to see how well they charge / discharge. As the cells are noticeable different capacity, you may have to charge them individually to even their status out.

Going every 3 or 6 months on battery supply only, gives a chance to measure voltage drop across contacts, with a chance to correct ones on the high side, after the test is complete.

After all of these a full load test can be performed. After all the preparations, It adds the information, how aged the cells are, to what degree they already lost their capacity to be charged. Without the former work and balancing the cells, the test is rather meaningless.

We are not talking about much time expended, maybe 3-4 hours monthly. Any repair is an add-on.

Lead-acid batteries last the longest in a fully charged floating condition. Full load test is needed be reasonably short, as the heat generated warps the plates and gradually loosens the oxide mass in the grid, by the heat generated.

If the battery is in float and near its full charge always, there is no need to discharge. There are portable equipment to measure impedance of each cells and you can be forewarned about health of each cell. You can see literature of Midtronics on this.

You have to tell us the type of battery as well for a proper answer......I could assume lead acid, sealed or not.....but would I be right?

If you don't test them you won't know what their condition is.

2 years is a pretty long interval.

There are battery monitoring systems that don't don't depend on discharging.

Guest1947 mentioned Midtronics. Cellwatch is another. Happy Googling.

To discharge a flooded lead acid battery (biased on your description as industrial) to the minimum voltage limit is detrimental, and doing it at a rapid rate compounds the damage. I prefer to discharge to a standardized 50% depth of discharge, and examine each battery for voltage drop; logging the measurement so it can be compared to previous tests. Variations in specific gravity should be tested and logged to establish a trend in change. If a problem is found in one of the cell or a battery, then a discharge test can be preformed; it will probably end the life of the battery, and prove the need for replacement simultaneously. People in the business of selling batteries will not agree with this for obvious reasons.

I also worked in a power station and had responsibility to monitor our battery bank. Specifications required we had the ability to conduct emergency switching during a major power outage of 8 hours. We conducted monthly SG testing. A glance at the resultant records, with or without plotted graphs, quickly identified failing cells long before they failed the mandatory discharge test done once every two years.

As long as the cells are recharged right after being discharged, harm is minimal.

The discharge test should not be done before you have carried out normal maintenance such as SG test and topping up electrolyte. If you have the kind of cell casing equipped with bubbling tubes a cycle of bubbling to destratify the electrolyte is recommended. Monitoring all cells for temperature is also recommended. Incipient problems will often be revealed first as a rise in cell temp. Hand held IR meters are cheap enough there is no excuse for not using them.

Congratulations!

Every single contribution is a part to a teachable moment. Now, you know more, than most other people about maintaining batteries.

Best regards. And you owe us the results.