At the CT regional team 95 experienced two battery failures. The first was a total dead short or broken tab. The battery failed a load test and measured around 0.001-0.005V with a multi-meter. No chargers or connectors were wired backwards and there was no obvious issue with any of the charging ports. After our final match the battery came out with acid slowly spraying out of the cap/seal on the top of the battery. :eek:
Thanks a million to 195 for giving every team a spill kit with a box, gloves, and baking soda. We used ours to keep a potentially dangerous situation contained. ::safety::
Now, both of these batteries were new in 2013, and are the only two battery failures I’ve experienced first-hand. It was also the first time we used these chargers from AM.
Have any other teams seen failures like this? Related to 2013 batteries or those chargers? Could there be another cause?
I’ve seen many teams over the years pick their batteries up by the leads. This is a dangerous practice. It causes internal stress on the tabs and can lead to failures like this. Any chance that happened here?
No, we do not. I watched our student who was in charge of batteries handle many swaps without once using the cables as a handle. I have a high confidence that this was not the issue.
There are two consistent failures that I have seen over the years. A quick inspection of the case will usually show some evidence of being dropped. This is easy to pick out if it occurs on a corner. When a battery is dropped the internal plates of the battery can shift within the cell. With the use of absorbed glass mat, I believe this might lead to a shorted cell. Once the cell shorts, significant heat builds up withing the cell causing the leaking acid and bubbles you experienced. I also have a theory that in the event of a either a failure for a normal charger, or the use of a high current charger, the plates will deform under the high current and also cause an internal short. To achieve a zero volt output, the battery would have to electrically open. This can occur if the connector plates between cells should break or melt open or the terminals become dislodged internal to the battery. The battery is manufactured with round terminals. Depending on the external terminal type ordered (there are several), the terminal is placed down on the round terminal internal to the battery and then it is flow soldered. To finish, a red or black epoxy is then added to seal the top of the battery. It is possible to break the solder joint (usually by lifting by the cables) and still not find any movement in the terminal.
I’m curious as to whether the batteries were both EnerSys batteries, or both MK batteries, or one of each?
PS: Congrats on a great performance at the CT regional! At the end of GSR, I thought it would just be a matter of time before The Grasshoppers would be making the 30-point climb regularly!
Team 1806 has done so for years now.
Our original handles were 2 zip ties that wrapped around the casing that linked together a cable covered in plastic tubing.
This year our battery handles are a strong blue woven material attached to the battery top by a mounting plate that bends into the normal handhold for the battery. The mounting plate also contains battery identification information, as well as a QR code that links to the material information and proper disposal information for the battery.
I was going to use S.W.A.T. as an example, but Woolly beat me to it. I will say that their system is really nice; it’s simple & sturdy. I will also say that when I inspected them at GKC I had to look twice at the battery; if you only glance at them it looks like they’ve drilled into the case. :eek:
We have had two, new 2013-purchased MK batteries fail this year. Both times the batteries leaked acid from the vent area, and both times were in practice at our field.
This year we have our battery lying down under the robot, with a plug-type piece keeping it captive in place, holding it on the top. We think that the leaks occurred due to it being a tight fit, and taking a few hard hits during practice against other robots. This may have put enough pressure on the seals to break them enough to allow a small leak. We have since replaced the plug with one that is shorter and added more foam to each end to help absorb impact. Since then we have not had another failure.
Thankfully both times, the leak was small, found quickly, and any spill was cleaned up fast. Just in a very inconvenient location.
We haven’t had any batteries fail this year. Usually though, they can fail due to multitudes of different reasons. Carrying the battery via the cable, dropping, or accidental shortage (my personal method of killing a battery one year).
Using the battery beak is one way to prevent issues. Usually a battery that is going to die shows signs ahead of time. But nothing trumps good battery safety and care.
Also, we’ve been using a pair of the triple bank battery chargers for two years now. Only issue is that someone blew out one of the banks, so we have 5 batteries charging instead of 6.
We have had 4 fail within the last year. 1 at champs last year overnight began leaking. We quickly got it contained and cleaned up the next morning when we found it.
During build season we were trying to fit a battery into the practice robot for locating the battery mount and it wouldn’t fit, discovered that the battery had started to swell.
After that I bought a battery beak and we have been checking our batteries and pulling the ones that test fair out of service. We plan to use this to periodically check the batteries and track the data.
At QCR last weekend we lost 2 batteries that tested good but then immediately dropped voltage and now test bad. They were both older batteries, maybe 2010 competition season.
