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Old 11-11-2014, 07:28   #1
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CCA test accuracy?

Does a CCA test on a battery tell you anything worth while about amp hour health?

So I work for a car dealership and have access to some battery charging/testing equipment. I brought my 3 group 24 batteries in to work (1 is a 800 CCA cranking battery, 2 are 550 CCA 84AH deep cycle batteries)
to put on the charger / tester just to see what it said.

The batteries are only 2 years old and I knew they would test good but I was curious if in the future, would this type of test be able to give me any significant warning that the batteries were getting tired or bad?

Just to give you the results the 800cca cranking battery tested at 810cca, and the 550 cca deep cycle batteries tested at 595cca and 606cca
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Old 11-11-2014, 07:56   #2
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Re: CCA test accuracy?

Absolutely, it tells you one indicator of its health, the CCA. The cold cranking amps need to exceed how many amps the starter motor draws. The other important measurement is the total number of amp-hours that can be drawn from the deep cycle house battery before the 12 volt system is too low. The first measure is most important for a start battery and the second measure is most important for a house battery.

When you get it back to the boat put a clamp ammeter over the starter cable to see what the start motor draws....just so you know your starter motors draw is not close to what your start battery is capable of producing.
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Old 11-11-2014, 08:00   #3
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Re: CCA test accuracy?

Quote:
Originally Posted by ontherocks83 View Post
Does a CCA test on a battery tell you anything worth while about amp hour health?
In short, no.... It can give you some guidance IF you know and have the 20 hour data to compare it to.

Quote:
Originally Posted by ontherocks83 View Post
So I work for a car dealership and have access to some battery charging/testing equipment. I brought my 3 group 24 batteries in to work (1 is a 800 CCA cranking battery, 2 are 550 CCA 84AH deep cycle batteries)
to put on the charger / tester just to see what it said.

The batteries are only 2 years old and I knew they would test good but I was curious if in the future, would this type of test be able to give me any significant warning that the batteries were getting tired or bad?

Just to give you the results the 800cca cranking battery tested at 810cca, and the 550 cca deep cycle batteries tested at 595cca and 606cca
I have been around and around with Midtronics on this and these devices are for determining cranking ability but cranking ability does not correlate directly to Ah capacity. Many companies have tried but none have succeeded in creating a "quick" analyzer that gives accurate Ah capacity.

Heck even on used batteries a reserve capacity test (25A fixed) and a 20 hour capacity test (Ah capacity divided by 20 for discharge rate) don't line up, but they do when new.

A 20 hour rate is the closest to how we use our batteries on boats, and is the most representative, but also extremely complicated for a DIY or pro to conduct. Even with the right equipment this is still 30+ hours of testing & charging.

If you take a baseline on a new battery, then compare it from that point forward, to this baseline, it can give you some idea as to SOH but it is not accurate for directly comparing to Ah capacity, just to its own baseline measurement.. If you don't have a baseline, from when new, using the same analyzer, then forget it meaning anything even close to Ah capacity.

For example I just finished capacity testing an Odyssey TPPL AGM yesterday. It is rated as a 100Ah battery and it delivered just 84.67 Ah's. It is also factory rated at 1150 CCA and it still delivers a 1415 CCA reading on the capacitance tester despite being down over 15 Ah's.

Most would wrongly assume, by looking at the battery analyzers CCA reading in excess of the batteries rating, this battery must surely be producing 100Ah's, WRONG!!! D'oh.....

So this is a battery that is 15+ Ah's shy of its rated Ah capacity yet approx 265CCA above factory CCA rating.

Complicated & confusing stuff? You bet!!!

This is why I offer actual 20 hour capacity testing for my customers as well as owning three different capacitance testers. The only accurate test for capcity is a 20 hour test but with the right knowledge, & a baseline, the other testers can give you rough guidance.

While they are fairly accurate for CCA this does not translate accurately to Ah capacity..
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Old 11-11-2014, 08:06   #4
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Re: CCA test accuracy?

Still for a starter battery, you never want its CCA to drop below what the starter motor draws, or even start to come close, and that does matter.

As for the house battery....what Main Sail says.
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Old 11-11-2014, 08:10   #5
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Re: CCA test accuracy?

I guess my underlying question is, is there ever a scenario where a CCA test would show the battery is good but its amp hour out put is severly depleted?

For example can a deep cycle battery test at say 540cca's, but when you put its 20 hour load on it have it drop below 12.2 too soon? Are those ratings/test's directly correlated in some way or can you have one good while the other is bad?

Edit: Thanks Maine sail I didn't see your post before I posted this question.
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Old 11-11-2014, 08:16   #6
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Re: CCA test accuracy?

As the total number of amp-hours drops so would the total number of CCA's drop as the battery ages. But the CCA's would only be an indirect indicator and not a direct measurement of the remaining amp-hours that the battery can store. The CCA's that it can produce would not directly translate to amp-hour capacity.
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Old 12-11-2014, 21:57   #7
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Re: CCA test accuracy?

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Originally Posted by Maine Sail View Post
A 20 hour rate is the closest to how we use our batteries on boats, and is the most representative, but also extremely complicated for a DIY or pro to conduct. Even with the right equipment this is still 30+ hours of testing & charging.
..

does anyone make an automated system for this? I have done a couple manually but being on hand to watch the voltage at the stop time is hard.

IE I just bought one of these for AA batteries
MH-C9000 - Maha Energy

it charges them up at a set rate. discharges at a set rate to a set voltage, recharges at a set rate. and records the ah cap. basicly a charger / discharger / ah meter in one. but all automatic. stick batteries in, next day look at ah recording.

surly something for a big 12v battery wouldn't be any more complicated. just a biger unit to hander larger loads and more heat for discharging. something that automaticly starts and stops at the right voltage without having to keep an eye on it the whole time.
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Old 13-11-2014, 02:38   #8
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Re: CCA test accuracy?

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Originally Posted by ontherocks83 View Post
I guess my underlying question is, is there ever a scenario where a CCA test would show the battery is good but its amp hour out put is severly depleted?
Apparently so...



From http://batteryuniversity.com/learn/a...asure_capacity
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Old 13-11-2014, 06:03   #9
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Re: CCA test accuracy?

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does anyone make an automated system for this? I have done a couple manually but being on hand to watch the voltage at the stop time is hard.
If you have $200k then the Digitron is a great tool. Trojan, Enersys etc. all use them..

For the tech there are lab grade DC Electronic load devices that can be used. Some are better than others but they all run in the $700.00+ range. BK Precision etc. make them. I have two lab grade DC Electronic load devices that can do up to 40A, which suffices for the 20 hour rate for just about any battery found on a boat. In order to need more than 40A you would need a single battery of 800Ah's...

Good quality DC Electronic loads also have dedicated voltage sensing for getting the correct cut off voltage. Be aware that not all of them have the ability to test batteries and display Ah's.

This is what the battery test screen looks like at 1:23 during a capacity test on a 100Ah battery.




Quote:
Originally Posted by smac999 View Post
IE I just bought one of these for AA batteries
MH-C9000 - Maha Energy

it charges them up at a set rate. discharges at a set rate to a set voltage, recharges at a set rate. and records the ah cap. basicly a charger / discharger / ah meter in one. but all automatic. stick batteries in, next day look at ah recording.
No one makes such a thing, that is affordable, for large batteries, and when they do they get very, very pricey and more complicated than necessary.

There are some Chinese Ah testers out there but they only do up to 10A. This precludes testing batteries over 200Ah's and their accuracy is questionable but could suffice for a general 20 hour capacity. For example 10A would exclude properly capacity testing most any 6V golf cart battery..

Quote:
Originally Posted by smac999 View Post
surly something for a big 12v battery wouldn't be any more complicated. just a biger unit to hander larger loads and more heat for discharging. something that automaticly starts and stops at the right voltage without having to keep an eye on it the whole time.
Some electronic loads have a trigger port which can fire up a charger when the battery hits 10.5V and most of them have the ability to do this through a computer interface.. As long as you don't turn off the DC load the Ah's and time run will remain on the screen, with many of them, or captured in the computer if so programmed....

This is what my customers, with expensive batteries, get on each battery tested.

*Battery cleaned
*Battery discharged to 11.7V then recharged to 100% SOC
*Battery conditioned or equalized if manufacturer allows it
*Battery rests for 24 hours in water bath set to 75-77F
*Battery undergoes 20 hour capacity test
*Label applied to battery stating load, temp, Ah's delivered and time



Over the years I tried using an Ah counter & resistors, light bulbs etc. but keeping the load constant was extremely difficult. I then had a custom built DC electronic load made (Mark Grasser) and then I finally bit the bullet and bought a lab grade DC Electronic load ...
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Old 13-11-2014, 06:22   #10
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Re: CCA test accuracy?

Dumb question but if I were to configure a load at my 20 hour rate and painstakingly monitor the voltage and that the current stays consistent do I want to end the test at 10.5 volts with the load applied or 10.5 after it recovers. I am assuming it is with the load applied but wanted to be sure.
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Old 13-11-2014, 06:55   #11
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Re: CCA test accuracy?

Quote:
Originally Posted by ontherocks83 View Post
Dumb question but if I were to configure a load at my 20 hour rate and painstakingly monitor the voltage and that the current stays consistent do I want to end the test at 10.5 volts with the load applied or 10.5 after it recovers. I am assuming it is with the load applied but wanted to be sure.
The test is cut off at 10.5V with the 20 hour load applied. If you run the battery until the "resting rebounded voltage" is 10.5 that would be pretty bad for it.

Done correctly a 20 hour tests causes no more harm a than any other deep cycle and can actually be less harmful than drawing to 50% and letting it sit there for a day or two before fully recharging.
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Old 13-11-2014, 12:56   #12
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Re: CCA test accuracy?

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does anyone make an automated system for this? I have done a couple manually but being on hand to watch the voltage at the stop time is hard.
On a very low end scale I played around using an arduino microprocessor for monitoring the voltage and amps on a discharge just through some car headlights. It shouldn't be too difficult to add a power transistor to maintain a constant current with a relay to disconnect the load at a given voltage. All the bits cost very little, the programming might be a bit of a hurdle for anyone who has never written any code before but not difficult really.

https://plot.ly/~Paddyb/1
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Old 13-11-2014, 13:03   #13
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Re: CCA test accuracy?

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On a very low end scale I played around using an arduino microprocessor for monitoring the voltage and amps on a discharge just through some car headlights. It shouldn't be too difficult to add a power transistor to maintain a constant current with a relay to disconnect the load at a given voltage. All the bits cost very little, the programming might be a bit of a hurdle for anyone who has never written any code before but not difficult really.

https://plot.ly/~Paddyb/1
Sounds like you should create a business!! I know there is a demand for an inexpensive capacity tester for deep cycle batteries and also that the average DIY does not want to spend $700.00+ dollars to do this....
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Old 13-11-2014, 13:49   #14
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Re: CCA test accuracy?

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Sounds like you should create a business!! I know there is a demand for an inexpensive capacity tester for deep cycle batteries and also that the average DIY does not want to spend $700.00+ dollars to do this....
I think coming up with a dedicated unit for sale might be a bit beyond me But for anchorage barter, definitely, I think there would be beers to be had amongst cruisers. I find it surprising many more people havenīt come up with similar, it really isnīt hard. With microprocessors like the wonderful arduino and a multitude of sensors now to be had on ebay for so little. I forgot to mention temperature, thereś an excellent temp sensor, waterproof and very accurate , ds18b20, you can get a bagful for price of a beer and a burger. Hereīs my fridge
https://plot.ly/~Paddyb/3/ambient-te...nning5on-4off/

Temp might be a big downside, I donīt know. If you had a discharge plot at 80deg, how accurate are the conversion coefficients from another plot at, say, 50deg?
Dunno, but on a cruising boat having a bit of a handle on the state of your batts Iīm sure would be much better than what most do now - wishful guessing

Also a handful of car headlights isnīt ideal for a load, must be an easier way..

For the battery discharge graph all you need is ..
Arduino uno or similar from the range
data logging shild with clock and sd card
current sensor. acs-something from memory.
Some resistors or easier a voltage reducer.
All available from ebay for very little.
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Old 14-11-2014, 07:19   #15
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Re: CCA test accuracy?

Conachair, parroting what Maine Sail said if you could build a reliable device I would be a buyer at $50-$100 for a plug and play unit. Don't get me wrong I'd prefer $20 but you gotta get paid for your time too
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