Engine/Transmission (1998.5 - 2002) How do you test batteries??

[Tomscreek]

My truck is going on 3 years old and entering another winter so I'm concerned about the batteries. How does one test the batteries? Can you do it with a multimeter? I called a battery shop and they said they'd do it. They also suggested a series 31 truck battery at 950 cca. Said they were cheaper than the Optimas ($92. ea) but requires some battery holder modification, a little plastic surgery I guess. They said the standard 700 cca batteries work ok too but of course the truck batteries are better. I did a search on batteries and WOW, lots of info. Actually the factory batteries seem fine now, I just don't want to find out at my remote cabin that they aren't up to snuff.

 

[BV]

Battery Testing

To test a battery you start with a volt/multimeter to check voltage then you would want to put a Battery Tester on them to confirm how well the battery holds that voltage.



The tester above is nothing special and basically is like an electric heater that puts a load on the battery and measures the voltage.



NOTE: You will want to separate the batteries so that they are tested individually so that you can isolate a weak battery if one is present.



Another Note: I also believe that both batteries should be replaced at the same time with a new pair that are of the same/type/size/mfg date. What this means is if you replace one then replace both and make sure they are identical and close to the same date. I have heard some even match the lot numbers.

 

[Rotty]

What "BV" said and do buy a mached pair (same mfg. date and or same lot)or as close as possible. Otherwise the old one will kill the new one is a short time.

This is especially true for large number of series or parallel batteries.

"BV" you read my mind on the load tester. There are other load testers of various current loadings. I have seen up to 500amp load but with the associated price too. I always like using a 100-200 amp load as this more closely simulated a good working starter. If the battery was starting to get weak, it would draw down pretty fast and if it was bad, it would almost die immedately.

You can also use a multimeter, but the voltage will depend on battery temp, charge condition and load. Using a multimeter will give you better indications of the charging system than how good the battery is holding a charge. What I always was taught that the charging voltage should be 14. 0-14. 6 with all loads running (lights, ac, fan on max, etc. ) 13. 5-14. 0 was ok, and anything less spells trouble and you needed to dig deeper(weak battery, weak charging system, bad cables or connections). If the voltage was less than 12. 3, then the alternator was not charging and it was either a bad alternator, regulator or bad battery.

The voltage must be measured on the terminals ( the actual lead posts) and not any of the connectors. If you have a bad cable or connecting the reading will be higher, thus giving you a false reading.

Always make sure the terminal connections are clean and tight. Use the proper tool to take apart and clean the lead connetions and then retighten them. It does make a difference. .

Sorry for the long post.

good luck...

 

[athompson]

Just replace them

If I were you, I'd just replace them and quit worrying about them. At three years old, they could test fine today and quit tomorrow.

 

[Tomscreek]

Thanks guys, good info. I'm with athompson, think I'll just get the 950cca truck batteries and sleep well. !!!!!

 

[JR2]

I have a buddy that owns a battery business. He has a load tester that goes to 1500 amps. I let him test my batt's. When I bought some slightly used optima red tops from him he tested them both to 1200 amps for about two minutes. Both batts stayed about 12. 5 volts for the entire time.

 

[PMalin]

You may try this, and initially take battery voltage measurements prior to startup, and then get either a (min max) function on your meter or someone to help. Take the measurement of the minimum voltage across your battery terminals, as someone starts the truck. This dip in voltage will be the result of the internal battery resistance if measured at battery teminals, which is a function of how good the battery is with the load you just applied, You may then divide voltage dip measurement / no load voltage measurement and get a relative idea of the effectiveness of the battery. I have not concluded what point should be the time to change batteries, but if getting below 70% I would think it's time. I was doing this with my old gasser and neaver done much with this yet on the cummins. As far as the battery load testers that can be connected to your battery, I have heard of problems with their use at times. If the technician doing the load test, sets the current setting too high, then when the test is applied, the huge amount of current draw can heat up and warp the plates in your battery, and if it's not failing after that, it may cause a reduced life of the battery. Be sure if someone connects one of these testers, they do not exceed the current rating specified for your battery.

All of this said, in real practice In the summer heat I have experienced times when a battery can work great one hour and be totally bad the next time you go to start it.