Battery Testing Procedure

Rudy Technician California Posted   Latest  

SInce I have soooooooooo much time on my hands here at the shop,Ive been watching various educational videos.

In this video a battery testing procedure is being discussed that I have never heard of before, as well as debunking the continued use of carbon pile testing. Enjoy.

(The battery testing in question begins around the 26.00 mark)

youtube​.​com/watch?v=7UAVc4…

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Patrick Diagnostician
Michigan
Patrick Default
 

The video is 100% correct. Twice in the past year I have told customers that their new "value" battery needs to be replaced along with my supplied alternator. These batteries passed the CCA and conductance tests but failed the amperage recharge test. I told them the alternator would not have a guarantee if it did not leave the shop charging less than 10 amps at idle.

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George Owner/Technician
Alabama
George Default
 

I have tested thousands of batteries and many thousands of alt/gen.. .Doing so I have never seen a battery drawing 40/50 amps,,Only heard of it ,Most I ever see is 5/10 amps​.​For a good battery and charging system the charge current is in the milli amps (200/300) after about 15/20 minutes with engine running. If one did have a battery drawing that much current then the mechanic did…

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Unprofessional
James Owner/Technician
California
James Default
 

Glad to see you are still in the game, George! I thought you were retiring!

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Rudy Technician
California
Rudy Default
   

George- Or anyone else, will the amperage draw of a battery increase somewhat linear as the battery starts to age? If it does, do you have and explanation or opinion as to why?

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George Owner/Technician
Alabama
George Default
   

Amperage will decrease linear​.​The plates get warn out...electrolyte gets contaminated....This causes the chemical reaction time to slow down also.... Temperature also is a factor......Also when the external load equals the internal resistance of the battery we will have max current available. A example of chemical reaction time was in one of Louis post where he had a vehicle that would not…

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Rudy Technician
California
Rudy Default
 

George- So the amps decrease with age? So if a battery is pulling over 10 amps,its not because it is old,it is because there is a defect of some sort internally?(assuming all other factors are normal) Ive amped clamped about 15 cars so far since I posted this and none were higher than 4-6 amps. The batteries were in various stages of decay(according to my conductance tester), but now I wonder…

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George Owner/Technician
Alabama
George Default
 

Rudy........ What was the final current after the battery finally got fully recharged from cranking the vehicle ? It should eventually go to milli amps after 10/15 minutes......What would be the effects if this 4-6 amps was constant ? Seems to me if you keep charging a battery with 4-6 amps after it has been full charged you gonna have short life due to electrolyte evaporation.

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Albin Diagnostician
Washington
Albin Default
 

That video is spot on. Over the years, I have seen a few batteries that would draw in excess of 30 amps, which each of those was in because the generators didn't last very long. I have a test all set up on my Pico that I use for testing batteries and generators & starters.

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Randy Diagnostician
California
Randy Default
 

I took this class many years ago and vince is right .. And I have proven it

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Gary Owner/Technician
Colorado
Gary Default
 

Thanks for the link, Rudy I've taken a few of Vince's classes many years ago, the video was a good refresher course...

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Michael Diagnostician
Illinois
Michael Default
 

The test is very reliable Rudy. I use it all the time and have specs on the buses I work on. If your curious about specs for certain batteries a lot of the time the manufacturer will supply specs for the maximum amount of current it is allowed to draw, even though the 10 amp rule Vince talks about for cars works very well.

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Carl Technician
Ireland
Carl Default
 

What sort of current draw are you seeing on 24v systems Michael? And on what Ah batteries? Carl

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Richard Technician
New York
Richard Default
 

I had kind of forgotten about this test. I had used on occasion in the past, I still like the carbon pile tester. I had a volvo xc90 yesterday that needed a battery. I used the test outlined and got this waveform. Drawing 38 amps at idle. The battery was bad, the battery also failed with carbon pile tester. Plus you see how low the voltage dropped during cranking. I would have gotten an after…

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