Test method for sealed lead acid batteries?

What is the most reliable test method for sealed lead acid batteries?

This has been something I have been working on for a number of years and now it is a matter that needs to be resolved for inclusion in Australian Standard AS1851.

In most cases, we use sealed lead acid batteries sometimes known as gel cell batteries in fire panels and emergency warning systems.

These systems usually combine two 12v batteries wired in series (24v) and range in size from 7Ah through to 200Ah.

The problem is that we are currently unable to determine if a battery will pass or fail under full load conditions.

I have trialled the following systems with inconsistent results;

  • NoClimb - Cellchecker Battery Tester
    Rather than simply displaying a voltage reading, Cellchecker? determines a battery?s remaining power capacity by measuring its ability to maintain voltage levels while under load. The tester then makes an assessment based on these readings and displays the remaining percentage capacity of the battery. Pulse load testers verify that a battery can deliver power by actually making it deliver power.
  • ACT - GOLD-IBT Intelligent Battery Tester
    The GOLD-IBT Intelligent Battery Tester solves this problem by measuring temperature, voltage AND capacity in under 6 seconds. It achieves this by performing a conventional 20 hour battery discharge in seconds using a patented pulsed frequency load test which accurately measures the available Ampere-hour (Ah) capacity based on the the battery?s temperature and condition of charge.

According the Cellchecker web site there are problems with each method of determining a battery's state of charge and condition;

Alternatives to Pulse Load testing

Depending on the type/chemistry of the battery, there are several different testing methods on the market. These methods include simple voltage measurement, coulomb counting, impedance / conductance measurement, and in some cases electrolyte analysis. Acceptable methods vary by battery type or chemistry.

For example, one of the characteristics of the lithium (LiMnO2) and NiMH chemistries is that they have a relatively flat discharge curve. This means that the battery's terminal voltage is nearly the same at 90% capacity or 40% capacity, compared to other chemistries such as alkaline or lead-acid whose voltage decreases steadily with discharge. Simply measuring the battery's voltage or even voltage under a small load, like many conventional battery testers do, is not, therefore, a reliable method to test these types of chemistries.

The alternative of measuring and recording the amount of current discharge (coulomb counting), has its drawbacks in primary cells because it assumes that the battery begins with full capacity ? an assumption that ignores age and other factors as well as assuming that the battery will be able to actually deliver its capacity at the necessary rate.

Impedance and conductance measurement methods in lead-acid type batteries also assume that the battery will be able to deliver its measured capacity.

Calling for your help?

As you can tell, I have been thinking about this for some time and now I am asking for your help for an answer... If you have a suggestion for a battery test method, system or a link to a great web site, then please add your comments below..

I look forward to your feedback..


Submitted by rporteous on June 8, 2008 - 22:36.

http://www.BatteryUniversity.com is an educational website that offers practical information for battery users. The material is condensed into easy-to-read essays of about 1000 words and covers most aspects of battery use.

More links for discussion
Submitted by rporteous on November 13, 2008 - 10:40.
  • http://www.batterystuff.com/tutorial_battery.html
  • http://autorepair.about.com/library/weekly/aa101604c.htm
  • http://www.portapower.com.au/Products/battery-testers.htm
  • http://www.uscar.org/guest/article_view.php?articles_id=74
battery testing
Submitted by Paul Coles (not verified) on September 2, 2009 - 01:17.

HI.have tested many batteries over last few years,mainly sla/agm/gell .Found only test that truly works is to discharge these at 20 amps regulated untill cell volts aprox 9. 5 volts on load.the time taken for ths is multplied by a correction factor which allows for battery amperehour and 20 amp discharge rate instead of c20 discharge time.i.e 50a/h batt duration of test 110 minuets. correction for this battery = 0.9727 110x 0.9727 = 107% pass. [% of rated capacity].

Correctiones obtained by testing neumerous batteries over the years and documenting 20ah discharge times.
testing times range from 18 min 12a/h to 220min 95a/h.

comercial testers Alphabatt pro and simular from M/K Batteries w ork simular to this and give perfect results ,these wont miss a faulty or lo capacity battery.

The small testers that analise internal impedance /chemistry .I had a battery sales rep call and brought severall types of these testers into the workshops and test 2x 35ah agm batteres; both proved faulty low capacity on 20 amp tester and alphabatt pro andhad been removed from electric vehicles because of low range. according to the salesmans testers gave readings of 100% charge 95% aprox state of health .allo did dentify 1 x 12ah faulty battery. so wolld not recomend these for anything outher than quick no go testng.


Hi Paul, I too work in the
Submitted by Alastair (not verified) on November 3, 2009 - 15:57.

Hi Paul,
I too work in the fire industry, and have been pondering how to load test batteries. The considerations are mainly that the equipment is relatively cost effective and also easy to use.
I would consider the 20amp load test method.
How do you calculate the correction factor?

Hi paulcan you tell me we
Submitted by singhkoshal on August 10, 2012 - 21:07.

Hi paul
can you tell me we have 2 sealed lead acid battery set 24v 200A10H,And 300A10H,on ship how to check capacity and what shold be end of discharge voltage each set have 12 cell 2v each. Also tell how to calculate capcity.

SixSigma test suggests electronic battery testers don't work!
Submitted by rporteous on November 3, 2009 - 10:48.

According to a large Australian fire protection company, they report that after conducting a SixSigma analysis of battery load testes, the electronic battery load testers (quick testers) are very unreliable.

Their test results suggest that in approximately 60% of the cases, these battery test devices failed to provide a consistent test result.

The conclusion being that these devices are not worth the price you pay for them!!!!

Submitted by singhkoshal on August 10, 2012 - 21:19.

can you tell me: we have 2 sealed lead acid battery set 24v 200A10H,And 300A10H,on ship how to check capacity and what shold be end of discharge voltage each set have 12 cell 2v each. Also tell how to calculate capcity.