Battery failures?

[JamesCH95]

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.

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.

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?

Thanks in advance.

[Racer26]

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?

[JamesCH95]

Originally Posted by Racer26

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?

I'd like to think not. We teach our students that batteries are to be picked up by the case, not the leads.

Neither of the terminals on the dead battery were visibly loose or cracked, FWIW.

[Ether]

Originally Posted by JamesCH95

We teach our students that batteries are to be picked up by the case, not the leads.

Do you provide a handle on each battery to remove the temptation?

[Gregor]

Originally Posted by Ether

Do you provide a handle on each battery to remove the temptation?

Do you have an example of even one team who does this?

[Ekcrbe]

Originally Posted by Gregor

Do you have an example of even one team who does this?

Would it even be legal to have something other than the leads and Anderson Connector attached to the battery? I think not.

[AdamHeard]

On the connector side we use the Anderson Handle meant to bolt to the battery for a few seasons now. They're really convenient.

[JamesCH95]

Originally Posted by AdamHeard

On the connector side we use the Anderson Handle meant to bolt to the battery for a few seasons now. They're really convenient.

Do you have a link or PN for those?

[Alan Anderson]

Originally Posted by Ether

Do you provide a handle on each battery to remove the temptation?

Originally Posted by Gregor

Do you have an example of even one team who does this?

We have a couple of battery carrying handles that see occasional use, but not as a regular practice.

[Al Skierkiewicz]

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.

[Woolly]

Originally Posted by Gregor

Do you have an example of even one team who does this?

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.

[Jaxom]

Originally Posted by Woolly

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.

[fb39ca4]

Originally Posted by Gregor

Do you have an example of even one team who does this?

1983 has fabric pouches for each battery with a handle.

[Navid Shafa]

Originally Posted by fb39ca4

1983 has fabric pouches for each battery with a handle.

I believe we've been doing this for four years now. They are really handy and I like how they look

I'll edit this post and add a picture to it tomorrow night.

[SteveGarward]

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.