Limitations of Battery Conductance Testing.

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I have a Midtronics PBT-200 tester, about twelve years old. It works well on my Sierra Size 78 battery. A new battery will read around 720 CCA and will lose about 50 CCA every year. I replace the battery when the CCA drops to around 500.

However it does not detect loss of capacity in Size 31 HD truck batteries. The batteries only last about three years because of cycling caused by electric motor powered hydraulic tailgates. I tested the old batteries and they read about 950 CCA each. New they register around 1000 CCA. However, applying a 25A load reveals that the Reserve Capacity had degraded to about 80 minutes from the rated capacity of 185 mins.

I replaced the batteries. Maybe conductance testing technology has improved in the twelve years since I bought the tester.

Just checked the Midtronics site and they rate the PBT-200 for up to 850 CCA. My tester displays 1000 CCA on new batteries.
 
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I don't know. I've had a store's (Batteries Plus) Midtronics check of my car's battery test good, but I replaced it because it wouldn't start the car after sitting overnight. That was earlier this year.
 
There is a joke we have about battery testers. You use conductance testers to upsell batteries, but you use a load tester to test batteries.
 
Dunno about your tester...but if you have liftgates...I started buying the Alliance branded AGM group 31's from Freightliner a few years ago. Deka makes them. If you buy the 8A31 version your battery problems will disappear. In applications we used to get 12-18 months out of, we now get 4 years plus. Usually between 175 and 200 CAD.
 
Alliance/Deka is what I buy, specifically AE1131XMF. The 8A31, being AGM, is expensive compared to the 1131. I just bought five of the 1131 at $116.xx each and I got $25.50 each for the old ones from my friendly metal recycler, bringing the cost down to $91 each. I get three years of dependable service out of them and replace them every three years. From the long term cost standpoint it is significantly less expensive to use the 1131.

I have tried the dual duty (starting/cycling) batteries (31S9D, I think) from Traction before and got an extra year of life but that could not make up for the extra cost.
 
I've found carbon pile testers to be extremely accurate in determining battery condition. These newer load testers lack the ability to truly load test a battery.
YMMV

Smoky
 
My issue with load testers is that it is only a pass/fail type of test. It does not tell you how close the battery is to failing.

The 100 amp hand held load testers do not help much in evaluating a car batterys health. They are adequate for checking small batteries like a motorcycle battery.
 
My Midtronics loads the battery with short (milliseconds) pulses of current of about 300 ma. It measures the voltage drops across the battery arising from the load and calculates CCA from the data. The tester uses Kelvin clamps to ensure accuracy of the voltage drop readings.
 
Originally Posted By: George7941
My issue with load testers is that it is only a pass/fail type of test. It does not tell you how close the battery is to failing.
My load tester is similar to the one the Mercedes specialist in the linked video used. It's got an analogue scale, and I check the battery in each vehicle before winter. Low in the green is not as good as higher, and as soon as a battery drops into high yellow I'll replace it. Both of our vehicles are '09s, each w/ the original battery, and both were still in the green as of a couple of months ago,so I imagine both will be good through the winter but that I'll be replacing them in the next year or so.
 
Originally Posted By: George7941

I have tried the dual duty (starting/cycling) batteries (31S9D, I think) from Traction before and got an extra year of life but that could not make up for the extra cost.


Ya...my first foray into the AGM world I did the dual purpose route...and got similar lousy results (the 9A31's). Once I went to the 8A31's it got good. My cost on the 8A's is $175..we use scrap money to fill the beer fridge so it stays off book
whistle.gif


Three years of liftgate work on the batteries you're buying is excellent...you guys must know the value of clean connections and good cables very well!
 
I keep the cable terminals clean. Every time I disconnect the cables I scrape off any corrosion, spray down with battery terminal cleaner, renew the felt washers and spray again with battery terminal protector after reconnecting.

Since I am the only one who works on the trucks, I would have only myself to blame for corroded terminals, stripped drain plugs, stripped lug nuts etc. These things just do not happen because I am very careful and methodical.

Here is the battery Terminal Cleaner
http://crc-canada.ca/automotive/battery/battery-cleaner-with-acid-indicator-312-grams.html

Terminal Protector
http://crc-canada.ca/automotive/battery/battery-protector-213-grams.html

I tried dielectric grease + baking soda paste, highly touted on Bitog, but found it to be ineffective.
 
George7941, grease, whatever is in the gun, a gob and a daub with a rag to work it in. The insulation shrinks at the end, exposing copper braid. Pay special care to any exposed metal. I can get a volt or 2 between Neg and a dirty battery top. Try it. Maybe use a soap or degreaser to keep battery top clean. Detailers use Pledge??
 
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