Who has had a leaky battery this year?

[Steven Sigley]

Originally Posted by ENIAC

Our batteries are placed in the robot horizontally, but we did this in 2010 with no issues. This year, two batteries, one that was used in the robot and one that was just sitting on a table, showed up with staining beneath the tape holding on the label.

I believe we cracked the glass on the inside of our batteries by playing with them laying horizontally in 2008 at the San Diego regional. No idea if problems like leakage could be related though. (I've never observed any leakage myself)

[Ether]

Originally Posted by Steven Sigley

I believe we cracked the glass on the inside of our batteries

The "glass" is a fiberglass mat. Perhaps someone who has taken one apart could comment on how brittle it is and likely it would be to crack.

[tsaksa]

Originally Posted by Ether

The "glass" is a fiberglass mat. Perhaps someone who has taken one apart could comment on how brittle it is and likely it would be to crack.

I believe the glass mat is not very brittle, but perhaps I can track more information down without needing to dissemble a battery. By a strange coincidence the battery separator material is actually made in our town.

[PAR_WIG1350]

Originally Posted by Ether

The "glass" is a fiberglass mat. Perhaps someone who has taken one apart could comment on how brittle it is and likely it would be to crack.

Wikipedia has some decent images of that.

[Steven Sigley]

note: DO NOT OPEN UP YOUR BATTERIES EVER. Thanks for your time

now for the lazy:



Also these look roughly like what we use if i had to guess

[tsaksa]

An important note. Both batteries were labeled with a large paper label and tape that covered the area marked (pressurized vent system). There was also very little liquid present, and it was only noticeable because there was paper and tape trapping it in the area we now know is a vent. There is at least some possibility that the batteries did not actually leak, but that it was just that the tape trapped and helped to condense normal venting gasses.

I will carefully look over the batteries later this week and see if this may be the case. One interesting fact is that the person responding to the leak commented that baking soda did not fizz when dumped on the battery. This along with the very limited amount of liquid suggests to me there is at least some chance that this is not a classic spill.

Don't worry, I will be careful. I just want to make sure that we know what happened. I suspect that we may at least want to have whoever labels batteries in the future be more careful not to accidentally cover the vent area.

[marccenter]

We had two batteries leak in 2011 - new ones from FIRST. We checked the chargers for current, voltage, etc? and was not able to determine the nature of the cause. We had FIRST personnel at the Troy district tournament last year working with us to help figure our the issue to no avail.

Speculation on my part is that the batteries may have been dropped in shipment.

[Al Skierkiewicz]

T,
A normal by-product of the charge and discharge cycle is water vapor due to heat genrated within the cell. The vents open to release this pressure in the form of vapor. Even though the manufacturer says the battery can be charged in any orientation, I recommend that the battery only be charged in the upright position. Any liquid at the vent will be forced out when the cell pressure exceeds the vent trip. That liquid then pushes out of the vent. Following the charge cycle this water then recombines in the cell. As a battery loses water, it's peak capability is also lost. In gel cells this is more of an issue as the gel then decreases to the point were the plates are not fully covered by electrolyte. With gel cells it is/was easy to pickup a battery and actually feel the weight loss compared to a newer battery.

[tsaksa]

Originally Posted by Al Skierkiewicz

T,
A normal by-product of the charge and discharge cycle is water vapor due to heat genrated within the cell. The vents open to release this pressure in the form of vapor. Even though the manufacturer says the battery can be charged in any orientation, I recommend that the battery only be charged in the upright position. Any liquid at the vent will be forced out when the cell pressure exceeds the vent trip. That liquid then pushes out of the vent. Following the charge cycle this water then recombines in the cell. As a battery loses water, it's peak capability is also lost. In gel cells this is more of an issue as the gel then decreases to the point were the plates are not fully covered by electrolyte. With gel cells it is/was easy to pickup a battery and actually feel the weight loss compared to a newer battery.

Thanks.

I had a feeling the labeling was a tad excessive and the batteries may not have been really leaking. I will discuss this with the team and make a plan for how to proceed. Batteries remain one area where we need to exercise more diligence.

[DonRotolo]

OK Folks, after 25 years in the industry, I think I know a little about batteries, maybe. Search my posts to be sure.

We had a battery start leaking at the negative terminal this year, a 2011 battery. It was charged properly, handled properly, etc. Literally out of nowhere it started to leak.

I'll be cutting that one apart* to analyze that failure later this season. For now it is contained properly. More soon.

* I am a trained professional and have cut (literally) thousands of batteries apart in my career. I have seen people injured badly by flying highly-concentrated sulphuric acid and small chunks of lead while doing this. If there ever was a time to hear and obey this, it is now: Do not try this at home.

[Bill_B]

I just took a close look, in pretty good light, at one of the batteries looking for the vent(s) mentioned above. I'm presuming it/they is somewhere in the black "cap" on top, but I did not recognize anything obviously as a vent. It all looked pretty solid to me. I was wonder what part could be taped over to cause a problem.

[Nirvash]

Originally Posted by Bill_B

I just took a close look, in pretty good light, at one of the batteries looking for the vent(s) mentioned above. I'm presuming it/they is somewhere in the black "cap" on top, but I did not recognize anything obviously as a vent. It all looked pretty solid to me. I was wonder what part could be taped over to cause a problem.

On the top of the batteries there is a small plastic strip that hides the vents, as show by a bad battery.
Vents

[Al Skierkiewicz]

Bill,
I don't think that label caused the problem, it simply was the evidence of the vent.

[Diesel Torch]

Last year we lost 7 batteries because of leakage... This year we upgraded to new chargers and we haven't lost a single one...

[tsaksa]

Originally Posted by Diesel Torch

Last year we lost 7 batteries because of leakage... This year we upgraded to new chargers and we haven't lost a single one...

Did you switch to a completely different type of charger? If so, what were the old ones, and what did you switch to.

Also, Al Skierkiewicz I really like your list of battery rules. In particular
#6 Insist that only those students or adults that know how the battery is designed to be mounted in the robot actually place the battery in the robot.
I would consider extending this a bit and think our team perhaps should have a formal battery handling certification. I too often here a coach, driver, programmer, or mentor yell, "Anyone!, we need a fresh battery now." Somehow replacing a battery has become some time critical priority, and anyone is considered qualified to replace one. We are trying to get away from that, and insure that proper battery handling procedures are followed. But we seem to be fighting a lot of inertia.