Battery Beak

[BJT]

I'll buy one as soon as you shrink the picture and stop squishing the rest of the portal page. Seriously, I will

[DonRotolo]

Originally Posted by Ether

http://www.chiefdelphi.com/forums/sh...3&postcount=12

The web site states that it uses internal resistance.

The auto industry has been using internal resistance for battery health (but not state of charge) for many years. In general, the higher the internal resistance, the worse the condition of the battery. You must properly characterize the battery (chemistry, capacity) for this to work properly.

The screen display shows three voltage readings at different current values, I speculate that this is used in addition to internal resistance to measure battery condition. This is an even older (and some say more accurate) method for battery condition. In the auto industry, it is (or was) common to have a carbon pile load to test batteries, rule of thumb was 3x the Ah rating in amps, check the voltage at 15 seconds.

I will also speculate that state of charge is calculated by measuring open circuit voltage after a small load (like 18A for 10 seconds) is used to remove any possible surface charge.

Assuming the designer knew what she was doing, using these three methods (none of which are technically challenging) should produce repeatable results that are accurate enough for our purposes.

[Brandon Martus]

Originally Posted by BJT

I'll buy one as soon as you shrink the picture and stop squishing the rest of the portal page. Seriously, I will

haha .. that was my fault. i'll fix it.

[BJT]

Sweet, I just ordered one, thanks

[Mark McLeod]

I've found that I need the Large Print screen version
Works nicely. We'll run comparisons of the Battery Beak results against the battery test plots at our next meeting.

[Mike Copioli]

The Battery Beak User Manual is now up at: http://www.crosstheroadelectronics.com/Beak.html. Please let me know if there are any typos, errors or problems with the link.

[Mark McLeod]

Here is a good battery/bad battery comparison (actual size on my screen resolution).
The third one is the good battery fresh off a charger (now rated only Fair)

The bad battery's measured badness matches our team number.
Take this bad battery with a grain of salt, I have another one in mind to test with that I've already independently measured the internal resistance of.

[Mike Copioli]

Originally Posted by Mark McLeod

The bad battery's measured badness matches our team number. ]

This makes me laugh.


[/quote]

Mark,

The first battery on the left, the one that measured as bad is discharged, Charge the battery and then perform the test again. The last battery that measured fair looks like it was just pulled off of the charger, you should let it rest for about 15 minutes to an hour to allow the surface charge to penetrate the plates. You should see about a 10% decrease in the internal resistance after this.

[Mark McLeod]

These are only batteries that I happen to have at home (Well I do have more bad batteries here, but I'm not really interested in testing obviously bad batteries except for what help it can lend on team visits).
I'll do more extensive variations when I get to the shop.

Originally Posted by Mike Copioli

The first battery on the left, the one that measured as bad is discharged, Charge the battery and then perform the test again.

Nope, that bad battery is as fully charged as it will go
It really is a bad battery. It came from the recycle pile.

Originally Posted by Mike Copioli

The last battery that measured fair looks like it was just pulled off of the charger, you should let it rest for about 15 minutes to an hour to allow the surface charge to penetrate the plates.

Understood, someone PMed a question about what it looked like if (incorrectly) tested with a surface charge, as in rapid pit battery changes with the batteries fresh off a charger.

Originally Posted by Mike Copioli

You should see about a 10% decrease in the internal resistance after this.

The middle and right are the same battery after 10 minutes on a charger.
.026 (no surface charge) to .029 (with a surface charge) is the 10% difference you mention.
I'm waiting for the surface charge to dissipate again now to see if the resistance drops and the Beak returns to a Good rating.

[EricVanWyk]

Originally Posted by Mark McLeod

The bad battery's measured badness matches our team number.

For a moment I thought the Battery Beak would actually quantify a battery's "badness" and was brought back to the days of writing in LaTeX and getting "Badness: 10000" errors.

Mike, could you add a badness rating? Please?

[Richard Wallace]

Originally Posted by Mark McLeod

I've found that I need the Large Print screen version

That was my comment when Mike showed it to me at IRI. Al Skierkiewicz was nearby, and he had the same comment.
What do he and I and Mark have in common, hmmm ....?

Anyway, I ordered one on Tuesday and it arrived this morning. I'm hoping it will help my new team manage batteries better this year. It won't really matter if my old eyes can read the tiny screen -- the student who is responsible for battery charging will be recording the data, not I.

[Mark McLeod]

Originally Posted by Richard

What do he and I and Mark have in common, hmmm ....?

We're each interested in the big picture?

[Mike Copioli]

Originally Posted by Mark McLeod

We're each interested in the big picture?

Duly noted.

[Siri]

Originally Posted by Mark McLeod

The middle and right are the same battery after 10 minutes on a charger.
.026 (no surface charge) to .029 (with a surface charge) is the 10% difference you mention.
I'm waiting for the surface charge to dissipate again now to see if the resistance drops and the Beak returns to a Good rating.

So just to make sure I understand, if I use the Beak on a battery I just finished charging in the pit, the Good ones will read "Fair" because of the higher Rint? (Do Fair batteries read "Bad"? Bad ones still read "Bad"?)

What's the minimum percent Charge that still indicates a surface charge to you (somewhere between 130% and 113%, I take it)? Is surface charge ok in actual use of the battery?

Thanks! I suspect these are stupid questions to anyone with a modicum of practical EE knowledge, but I regret I'm not really one of those people. I do need to fix this.

[Ether]

Originally Posted by Siri

So just to make sure I understand, if I use the Beak on a battery I just finished charging in the pit

Don't do that. The results will be unpredictable.

Is surface charge ok in actual use of the battery?

Yes, assuming the battery is healthy and the surface charge is not fooling you into thinking the battery is good.

Thanks! I suspect these are stupid questions to anyone with a modicum of practical EE knowledge,

They are not stupid questions. They are important questions.