Explain to me the differance

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I'm trying to understand the the basic differance between a regular battery tester and one with a "Carbon Pile feature". What is the advantage of having said feature for the regular DIYer?
 
A carbon pile tester is the old school type with a knob so that you can match the load to the battery.
 
Not sure what you mean by "regular"?

1) Many load battery testers just put on a 100 amp load and measure the voltage. OK, but not very exacting.

2) With a carbon pile load tester you adjust the load for 1/2 the CCA for 15 seconds (it beeps) and check the voltage. The best test but the battery must be fully charged.

3) Midtronics, Solar, etc conductance battery testers can test the capacity of the battery in CCA even if not fully charged.

I just ordered a Solar one (#3) for $70.
 
Carbon pile vs what? The small toaster ones or something else?

While I am NOT a fan of HF, the one thing Ill recommend from there is their capacitive battery tester. It is about the same price as other brands, but it uniquely provides the value of impedance, which is the only characteristic of a battery that is worth a darn.

When youre running a carbon pile, which is a big resistor capable of handling a decent current for a short time, youre effectively measuring impedance - which manifests itself as the voltage drop under load. Vterminal=Vopencircuit-Current*impedance (roughly). So the little handheld thing is far more convenient than the carbon pile, though both have their place for sure.

The other brands dont offer impedance, so they arent worth it IMO. They give some arbitrary percentage, based upon some algorithm, but what it is and how it applies is anyone's guess.

For real testing and troubleshooting, you cant go wrong with a carbon pile or equivalent DC load with voltmeter. But the small things are helpful sometimes too.
 
I dont have a carbon pile because I have a DC clamp meter and can measure alternator voltage with the car loads on or starting. Since I know current and voltage, I can identify if the battery is weak. Im not a garage, so dont really do that much detailed electrical testing. I do have that HF tester because it is the only one Ive found that outputs impedance values.

Century Tool has a variety of fixed and variable load carbon pile testers that are made in the USA.
 
I'm with JHZR2 on this, but I have over 5 years experience as an automotive electrician. You develop a sense using the starter as load and a voltmeter. You'll miss one every now and then, but you'll do it anyway if you don't have time to fully charge a battery before load testing.
 
I'm with JHZR2 on this, but I have over 5 years experience as an automotive electrician. You develop a sense using the starter as load and a voltmeter. You'll miss one every now and then, but you'll do it anyway if you don't have time to fully charge a battery before load testing.
 
Starter/Battery/Alternator are always tricky. Most just throw parts at it. Correct diagnosis is always the first step!

Just pile into any AAP or such store and they will hook it up to a testing machine and quickly diagnose it CORRECTLY for you.
 
Originally Posted By: JHZR2
Carbon pile vs what? The small toaster ones or something else?

While I am NOT a fan of HF, the one thing Ill recommend from there is their capacitive battery tester. It is about the same price as other brands, but it uniquely provides the value of impedance, which is the only characteristic of a battery that is worth a darn.

When youre running a carbon pile, which is a big resistor capable of handling a decent current for a short time, youre effectively measuring impedance - which manifests itself as the voltage drop under load. Vterminal=Vopencircuit-Current*impedance (roughly). So the little handheld thing is far more convenient than the carbon pile, though both have their place for sure.

The other brands dont offer impedance, so they arent worth it IMO. They give some arbitrary percentage, based upon some algorithm, but what it is and how it applies is anyone's guess.

For real testing and troubleshooting, you cant go wrong with a carbon pile or equivalent DC load with voltmeter. But the small things are helpful sometimes too.


Gotta disagree with you, JHZR2. Measuring the impedance of the battery at any instant does not really tell you much about the battery because the impedance of the battery is not a constant but varies depending on its condition. The more it is discharged the more the impedance. A battery could very well have an acceptably low impedance at the beginning of a 15sec 400amp load but have high impedance at the end.

So, if you want to use impedance, you still need the 400 amp load first before you measure impedance.
 
Originally Posted By: George7941


Gotta disagree with you, JHZR2. Measuring the impedance of the battery at any instant does not really tell you much about the battery because the impedance of the battery is not a constant but varies depending on its condition. The more it is discharged the more the impedance. A battery could very well have an acceptably low impedance at the beginning of a 15sec 400amp load but have high impedance at the end.

So, if you want to use impedance, you still need the 400 amp load first before you measure impedance.



I agree that it is not a constant value. However one can see systemmatic trends and can also calculate voltage drop roughly at any point.

We always know the SOC vs voltage, within a tenth or so, temperature-dependent. And a multimeter is the easiest measurement out there... so one would instantly know if something within the battery is out of whack.

If the SOC is not at/near 100%, as it should reasonably be diagnosed that either something else is wrong (parasitic, short, bad charging system, bad alt diode, etc), and corrective action should be taken on the battery to (1) prevent further sulfation and (2) create a proper charging scenario.

The other thing is that putting a 400A test on there for a few seconds doesnt really tell much either. As you said, impedance differs with SOC, so the voltage at the high impedance point will drop harder/farther/faster than the voltage at the low impedance point. So where are you testing it, and how does that differ? All youre doing with the carbon pile is putting a load on it and seeing voltage drop - which is an impedance function - higher the impedance, the higher the I*R voltage drop.

And its not like a 400A load exercises the battry that much. Most SLI batteries are 500Wh-1kWh at the 10hr discharge rate (very low amps). At high rate, about 20-30% of the nameplate energy is accessible before they polarize and impedance causes an excessive voltage drop. But 400A for 15 s is a very small amount of actual total energy and thus SOC pulled out.

15s is like 0.00416 of an hour.

400A is at say, 10V, so its about 4000W times that long of an hour is around 16Wh. Even on a small 500Wh battery, its only like 3.2% of the energy withdrawn.
 
Originally Posted By: George7941
Originally Posted By: JHZR2
Carbon pile vs what? The small toaster ones or something else?

While I am NOT a fan of HF, the one thing Ill recommend from there is their capacitive battery tester. It is about the same price as other brands, but it uniquely provides the value of impedance, which is the only characteristic of a battery that is worth a darn.

When youre running a carbon pile, which is a big resistor capable of handling a decent current for a short time, youre effectively measuring impedance - which manifests itself as the voltage drop under load. Vterminal=Vopencircuit-Current*impedance (roughly). So the little handheld thing is far more convenient than the carbon pile, though both have their place for sure.

The other brands dont offer impedance, so they arent worth it IMO. They give some arbitrary percentage, based upon some algorithm, but what it is and how it applies is anyone's guess.

For real testing and troubleshooting, you cant go wrong with a carbon pile or equivalent DC load with voltmeter. But the small things are helpful sometimes too.


Gotta disagree with you, JHZR2. Measuring the impedance of the battery at any instant does not really tell you much about the battery because the impedance of the battery is not a constant but varies depending on its condition. The more it is discharged the more the impedance. A battery could very well have an acceptably low impedance at the beginning of a 15sec 400amp load but have high impedance at the end.

So, if you want to use impedance, you still need the 400 amp load first before you measure impedance.



You have my curiosity up. What would a Midtronics tester say at the start and end of a 400 amp load test?
 
Originally Posted By: JHZR2

I agree that it is not a constant value. However one can see systemmatic trends and can also calculate voltage drop roughly at any point.

We always know the SOC vs voltage, within a tenth or so, temperature-dependent. And a multimeter is the easiest measurement out there... so one would instantly know if something within the battery is out of whack.

If the SOC is not at/near 100%, as it should reasonably be diagnosed that either something else is wrong (parasitic, short, bad charging system, bad alt diode, etc), and corrective action should be taken on the battery to (1) prevent further sulfation and (2) create a proper charging scenario.

And its not like a 400A load exercises the battry that much. Most SLI batteries are 500Wh-1kWh at the 10hr discharge rate (very low amps). At high rate, about 20-30% of the nameplate energy is accessible before they polarize and impedance causes an excessive voltage drop. But 400A for 15 s is a very small amount of actual total energy and thus SOC pulled out.


Re SOC vs Voltage, check this thread out for my weird OCV
http://www.bobistheoilguy.com/forums/ubb...726#Post2973726

The 400A test is only good for seeing if there is any life left in the battery at all i.e. the battery will be able to start the engine at least once if it is charged (given same temperature testing vs starting)

A toaster will have to be left on four times as long, 60 seconds and they are not designed for that and will burn up inside.

Conductance testers give you an accurate picture most of the time but not always. Measuring the SG of the acid is a pretty good test if you can open up the caps on the battery.
 
There is a bit of diagnostic knowledge needed to use a carbon pile/voltmeter/ammeter. If you know what you are doing, you look at the voltage slope during the test and you can tell the difference between a weak/slightly weak, or bad battery. We used the tried and true Sun VAT40 for years. The problem came when FoMoCo decided we were throwing in too many batteries under warranty. Ford eventually forced us to the digital tester that spit out a fail code specific to the work order number. Never had a problem with it. Of course, I never threw a lot of batteries at vehicles either.

If you know what you are doing, a carbon pile w volt/ammeter is the best way to check a battery, IMHO.... IF you know what you are doing (had to repeat that part). Battery charged...yep, voltage measured..yep, then test. Anytime you test a batt, I think it is mandatory to check alt output (which is easy with a carbon pile to load it up), voltage, battery draw amperage when charging. Replaced an alternator (when I was a youngling) one time on a car that had a bad battery that sucked 45-50 amps continuously from the alternator. That alternator was full fielding just to keep the AC blower and other electrical accessories going. Alternator lasted a week before the solder melted out of the diodes.

With all that said, I bought the HF digital tester, just because....... Used it more than a few times on my tractors, and daily drivers, and motorhome, and it has been spot on at finding batteries that are on the way out. Easy to carry, and a no brainer to use. Ahhh, to get old and lazy.
 
The issue comes in when we are helping friends or family with a bad battery. One cannot wait or maybe cannot be there when the battery is fully charged on an AC charger.

It seems that is where a capacitive battery tester comes into play.
 
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Like punisher stated, capacitive testers are great for keeping an eye on the battery. I test the battery in my Sierra every year and it loses about 40CCA a year. When it gets down to 500 CCA i will replace it because I do not want a marginal battery in our cold winters.
 
OK, my example. GF's car died. She called AAA. They jumped it. She drove home but stopped at food store. Would not start. She called me. I came with my jumppak and jumped it. She needed to use the jumppak almost every time after that. I verified (or tried) water level in cells (maint free, no cell caps). No corrosion around terminals. Voltage was 14V with engine running even when I put some load on it from carbon pile tester. Tried to charge it overnight, but my Century charger may no longer be working as it did not help (something else to look at). Still unsure if something had been left on and the battery had never really gotten charged after that.

She went to PepBoys, they said the battery had less than 1/2 the CCAs it should have (maybe 225) so battery was shot.

Had I been able to test it when she first called me she could have saved some aggravation and gotten a new battery a few days sooner.

So my conclusion is a carbon pile load tester is a great device but really only helps for your own batteries where you can charge them overnight and test in the morning.
 
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A carbon pile is somewhat useful, but not conclusive in giving you confidence that a battery will crank your car the next time.

CCA tester gives you a number to work on with more confidence.
With less than 70% of spec, you should be looking at changing out your battery.

However, it's also not 100%, as I had batteries which measures full spec but failed after several days of "sitting" down and doing nothing.

These batteries were confirmed to have bad electrolyte which would have been found out by hydrometer.
 
Originally Posted By: kb27
A carbon pile is somewhat useful, but not conclusive in giving you confidence that a battery will crank your car the next time.

CCA tester gives you a number to work on with more confidence.
With less than 70% of spec, you should be looking at changing out your battery.

However, it's also not 100%, as I had batteries which measures full spec but failed after several days of "sitting" down and doing nothing.

These batteries were confirmed to have bad electrolyte which would have been found out by hydrometer.


Not sure I agree. The carbon pile tester is very good at telling you how a battery will react to a load such as a starter, but the battery must be full charged.
 
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