Battery Beak

[Siri]

Originally Posted by Ether

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

Ok, we'll continue to just run these tests pre-competition, thanks. How long is long enough to wait after charging, or are we waiting for a specific charge percentage?

[Ether]

Originally Posted by Siri

How long is long enough to wait after charging

Some websites say 48 hours (for automotive lead/acid batteries). The user manual for the FRC tester says 15 minutes if charge rate is limited to 6 amps (FRC battery is smaller).

[DonRotolo]

OK, so here is a challenge for the students out there. No fair if you've left High School...

Given the claims of the Battery Beak, design experiments to verify that it really works. Claims include:

Determines battery State of Charge
Determines battery internal resistance
Labels the battery good, fair or bad
Provides results in a second or so
Surface charge dissipates in 15 minutes at a slow (<6A) charge rate
>all assuming a standard FRC battery at room temperature

Pick one or more of these claims and figure out how to verify it.

Any takers?

[Mike Copioli]

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, the Good ones will read "Fair" because of the higher Rint? (Do Fair batteries read "Bad"? Bad ones still read "Bad"?)

Not necessarily, the batteries Mark tested had a higher than normal internal resistance it just so happened that the last battery was right at the threshold between 'Good' and 'Fair'. I would reserve that battery for practice only. A good rule of thumb for surface charge in SLA like the ones used in FRC is 10%. What this means is; if you take a battery directly off of a charger and then test it you get a 10% increase in the internal resistance and SOC from the surface charge that has not had time to penetrate the lead plates. For a healthy, new FRC battery this should not cause a 'Good' battery to read 'Fair'

Originally Posted by Siri

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?"

Surface charge is a result of the chemical reaction inside the battery being slower than the rate of charge provided by the charger. There is always some surface charge when a battery is first removed from the charger due to this reaction, it is perfectly normal. Again it accounts for apx 10% of the total charge in FRC. In other words the surface charge is deterministic and not unpredictable. So if you wanted to test your battery right after removing it from the charger just deduct 10% from the result. Or let it rest for about 5-15 minutes.

Originally Posted by Siri

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.

These are valid questions that we asked ourselves during the time spent developing this device. As it turns out surface charge is not a large of a variable as we expected.

[Mike Copioli]

And just to clarify one point:

Surface charge will NOT cause the Battery Beak to read a 'Bad' battery as 'Good'. I would stake my reputation, my company and my NON ANONYMOUS user name on it.

[Ether]

Do users need to be concerned at all about the battery temperature affecting the readings (e.g. cold trailer in the winter, hot trailer in the summer)?

[Mike Copioli]

Originally Posted by Ether

Is this true even if the battery has been charged at a rate higher than 6 amps, and is hot?

Yes, surface charge is weaker than deep charge. This behavior causes a small increase in internal resistance as measured by the Beak. This increase, if the battery's internal resistance is within 10% of the threshold between 'Good' and 'Fair' or 'Fair' and 'Bad', could only cause a battery's status to appear worse than it would be if the battery had been properly rested. This is one of the reasons the 'Fair' Status exists, otherwise it would just be 'Good' or 'Bad'. If a battery is that close to the threshold you should probably reserve it for practice only.

[sanddrag]

I know some other teams have used the CBA III from West Mountain radio as a battery analyzer, and I'd speculate there are others available. I like that the Battery Beak is all self contained and does not need a computer interface. Is there anything else that compares? I just want to look at all available options before I go buy one.

[Mike Copioli]

Originally Posted by sanddrag

I know some other teams have used the CBA III from West Mountain radio as a battery analyzer, and I'd speculate there are others available. I like that the Battery Beak is all self contained and does not need a computer interface.

The CBA series of testers measure battery capacity by applying a load until a specified cutoff voltage is reached and then calculating capacity in Amp Hours, the Beak measures battery internal resistance by applying two different loads and then calculating internal resistance. Both tests are of value and important to understanding the health of your battery. What the beak provides is a quick way of assessing the health of your battery between capacity tests at competitions without completely discharging your battery.

Originally Posted by sanddrag

Is there anything else that compares? I just want to look at all available options before I go buy one.

Internal resistance testers have been around for years, but most of them are very expensive. As far as I know the Beak is the only internal resistance tester that was specifically designed around the types of batteries used in FRC, VEX and FTC.

[alphadog0309]

Would this be a relevant purchase for FTC teams? We've been having some battery issues recently and we are looking at all possible ways to fix these issues.

[Mike Copioli]

Originally Posted by alphadog0309

Would this be a relevant purchase for FTC teams? We've been having some battery issues recently and we are looking at all possible ways to fix these issues.

Yes, in fact the Beak was designed to work with the 12 volt 3000 mAh NIMH batteries used in FTC.

[Mike Copioli]

A short video of the Beak is now available. Special thanks to Lauren and Adam from team 3539, the Byting Bulldogs.

http://www.crosstheroadelectronics.com/Beak.html

[nuggetsyl]

I have not read any of these posts so if i repeat something sorry. I saw this in action at IRI. There is no question in my mind that its a must to be a top level player. Even if the voltage is high it can still tell when a battery is about to fail. Don't be cheap buy the device. Each first round costs a team about $500 to play. Think of this as insurance that you be playing the round and not sitting with a dead robot on the field.

[Marvin Kraska]

Just got mine - looks like it will be a great time saver in the pit, should help us sort out all our batteries. I really like the quick test and display. It absoutely confirmed a marginal battery that we had marked as "suspect" from competition.

Thanks!!!

Originally Posted by Marvin Kraska

Just got mine - looks like it will be a great time saver in the pit, should help us sort out all our batteries. I really like the quick test and display. It absoutely confirmed a marginal battery that we had marked as "suspect" from competition.

Thanks!!!

On a scale of 1 to 10, 1 being "not worth your time", and 10 being "ZOMG MUST GET NOW WELL WORTH THE INVESTMENT", how would you rate it for a team?