I have a 2002 CCLB 4X4 with a 7.3.
My batteries are 3 years old and nearing replacement, (if you go by common wisdom on this board).
The other day I bought a battery analyzer and checked the batteries.
They both are about 620 CCA, versus the rating of 850 CCA on the tags.
The truck starts fine when the weather is warm, but the batteries seem to strain a little when it is cold (teens).
If I have the block heater plugged in, it starts like it is summer.

My question is, does anyone have a CCA level at which you should replace the batteries.
I am looking for data to base the replacement decision on.

LA

 

While I believe it is bad practice to wait till failure when talking about batteries, would also want to be certain they are past their service life too. Charge them both for several days at a low rate and then see if they will hold a charge and deliver a charge. If they're good they're good, if not not.

 

I hate being stranded but ... I personally wouldn't replace them until they actually become problematic. YMMV.

 

You could also check the cells. Top them off if needed. I say you still have some life in them, but plan on new batteries in the next year.

 

My factory batteries lasted from build date (June 06) until last December. They could hardly start the truck when it was -26F.

Even with a new battery (and a gas engine) you get a little slowing when starting in the cold cold weather.

At 620 CCA I think you are OK for another year, at least.

 

I have to agree with everyone else, I don't see any reason to replace batteries just because they are three years old. I replaced the factory battery in my 2000 Contour in 2010. Yeah, that thing lasted ten years.

Pretty sure 660 x 2 is plenty of amperage to start the engine even in cold weather. I'd wait until next fall and test them again.

 

as many have said...you can keep the battery as long as you can herky-jerky things to get it to work...but what you will find is that you are just transfering the costs eleswhere and in many cases more expensively. Choice is to replace your 169 dollar battery at some interval that makes sense or kkeep it til it dies and risk blowing out your alternator due to trying to keep a shorted battery charged. I could never understand why folks nickle and dime batteries and oil...meaning they try to run a 79 dollar battery for 7 years and a gallong of cheap oil for 5000 miles. The folks who try to strech things out seldom buy 169 dollar batteries or oil that is 7 dollars a qt.

 

When it comes to batteries, I have always done what most people do.
I keep the terminals clean and water topped off, and run them till I start noticing problems.
I purchased a Cen-Tech digital battery analyzer from Harbor Freight for a battery issue on another vehicle.
This analyzer is a pretty nice unit in that it will give you the voltage, CCA and resistance between cells.
I tested a new battery fresh from the store, it was a rated at 650 CCA, tested at 647, I consider this OK, since the battery was never used or charged.

My ultimate question is that based on CCA, what point do you just replace the battery?
My batteries are at 620, about 73% of the rating, or 1240 CCA total.
How much CCA does it take to start a 7.3 engine at 20*F ?

As Redford stated, I am probably good for another year.

LA

 

Proper battery & cable maintenance is good practice as mentioned above. Load test the batteries. If they pass why replace? IMO that's tossing money out the window and a wasteful use of resources. If your that **** about it buy a good Schumacher or Snap Off load tester and test them (it) periodically. I have a Die-Hard in my 68 Olds that's 12 years old. Granted its a summer show car but the battery receives proper maintenance. Battery tenders are great for this purpose. If you can get the caps off use a hydrometer to test each cell too. Thats a great way to see when the plates have oxidized beyond service life.

 

For me it would depend where you normally work/drive the truck. I spend a lot of time out in the boonies where you might go all day without seeing another rig, I don't like to push my luck with batteries. If you're in town where it's easy to get a jump then probably wait a year or 2.

 

With the winter we've been having , it gets well below freezing even in attached garage. Batteries like a boost charge every day. Since charging voltage is temperature dependent a battery can be slow charged at 30F without worrying about boiling a battery or anything getting hot.

The easiest test is the open circuit voltage or OCV. Battery chemistry was pretty much figured out a hundred years ago. First remove the surface charge from the battery. This makes for an accurate test. Turn on the headlights for five minutes. (Engine not running) Shut them off, wait ten minutes or more, and measure voltage at the terminals.

You'll need a digital voltmeter here. A modern "maintenance free" battery will bounce back to read 12.8 volts when fully charged at 77F or thereabouts. A tenth of a volt either or doesn't sound like much but really is. 12.1 volts would mean the truck might not turn over though. The resting voltage tells us a lot.. So 12.7 volts means an 80 percent charge or so.

Because the paradox is the only way to tell if you need a new battery is when they won't take a full charge or, deliver a full charge and to do that it must be charged to test it. (That we should be doing anyway) Charge it up, and then remove surface charge, try again. A conductance tester will be more accurate with a fresh charged battery. A weak or sulfated battery just looks like a dead short to the alternator. A weak battery will sometimes test falsely at a good OCV. But it has poor capacity.

If you can safely disable the ignition measure the cranking voltage over 15 seconds and a good battery will not drop below 9.6 volts, depending on temperature. Wait ten minutes again, voltage should bounce back to 12.8 or close. This removes the surface charge, but also practical test and is a pretty accurate test. Charge battery up again. Etc.

My 1964 pickup will take a dead cell or failing battery no big deal, I would never try that with a my 2009 Ranger, too much modern electronics, something expensive will get roasted.

 

amazing that something so easy becomes so difficult in a forum LOL
age is irrelevant passing a load test is
I have only been a mechanic for 30 years so I have never heard of the diminished cca replace concept. For me its watch the voltages before during and after a proper load test with a carbonpile or eq... if its seems like a premature failure then look at cables, grounds, alt , usage ,etc
If you really want to get old school and become **** then pull out that hydrometer LOL

 

You replace the battery when it fails a proper test
Your batteries maybe in a reduced state of charge because of many factors, not enough charge time, cables, to long of a time between charge, larger than normal parasitic draw or some kind of battery failure. You should charge them with a decent charger then retest.
Starter draws are usually measured in amps and many starters have an on engine spec or a on the bench spec. The spec can also have engine and ambient temps associated with it. My AllData shows 230-630AMPS @ 150-200RPM and a no load of 170AMP max. for your truck. To test this you need some kinda amp clamp.

 

I had my batteries tested today. Not because anything is wrong, but because the pesky app on my phone told me its time. What the heck. Its free.

They did the water check on each cell, 6 cells x 2 batteries. One cell in the passenger battery "failed." All of the other cells tested well into the green, the "bad" cell was between green and red, but they called it a bad cell because of the difference between it and the others, which were consistently even. They then load tested them, both came up to 750CCA. Then they did the test with the machine that simulates a crank. The "bad" battery did dip to 9.56 volts, which is below the 9.65 they said was the "fail" point.

That said, just last week I started the truck on that one battery, and it started fine. So goes to show, batteries are important, but these old trucks can usually make due with what they have, but neither of my batteries are bad at all. They were manufactured Dec of 2012. They were installed under the Interstate free replacement program.

 

The charging system works together, battery and generator/alternator. It pays to check everything. Alternators and batteries can get spendy and don't overlook the starter here either.

Starter is only designed to operate for a split second. It's way too small for continuous duty. This works fine till either an engine is in poor tune, then the current draw will be ten times otherwise what it would be. This really takes a battery down.

Starters have a duty cycle too, that nobody ever follows, 10 seconds of cranking probably means wait 40 minutes and try again. Roasted starters leak current to ground seems to be common from reading here too, alternators will choke trying to charge that mess up. guarantees problems.