Battery failures?
 

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?

Thanks in advance.

Re: Battery failures?
 

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?

Re: Battery failures?
 

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.

Re: Battery failures?
 

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

Re: Battery failures?
 

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

Re: Battery failures?
 

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.

Re: Battery failures?
 

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

Re: Battery failures?
 

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

Re: Battery failures?
 

Do you have a link or PN for those?

Re: Battery failures?
 

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

Re: Battery failures?
 

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.

Re: Battery failures?
 

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!

Re: Battery failures?
 

They were both from FIRST Choice IIRC, though the totally dead battery has already been disposed of, so I can't confirm brands.

Thanks! It was a rough road, but we got there in the end.

Re: Battery failures?
 

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.

Re: Battery failures?
 

1983 has fabric pouches for each battery with a handle.

Re: Battery failures?
 

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:

Re: Battery failures?
 

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

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

Re: Battery failures?
 

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. :)

Re: Battery failures?
 

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.

Re: Battery failures?
 

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.

Re: Battery failures?
 

It turns out we are using the stock Andymark Pouches:
http://www.andymark.com/product-p/am-0620.htm

Re: Battery failures?
 

Thanks for all of the replies guys.

Al/Ether - A second inspection of the robot shows a spot where there is a remote chance that the battery lead could be pushed pretty hard by a mechanism. I think this could have caused one of the leads to fracture. This will be cured with better wire control.

Steve - Our robot also has the battery mounted low and without much padding, plus we played a good bit of defense. This seems a likely cause for the leakage failure. We'll look into padding options.

Re: Battery failures?
 

We had a brand new battery fail at us at South Florida. Apparently one of the leads of a port on the 3 port battery charger had its polarity switched in manufacturing. The battery would show 3-6 Volts after we noticed it had died.:ahh:

Teams need to check, and re-check the batteries and chargers before they put them to use!

Re: Battery failures?
 

We had a battery from 2011 which died this year. Cause of death was most likely being left discharged over the summer.

Showed ~10.5 volts which collapsed to nothing under any load, the Shumaucher charger would remain in desulfation mode indefinitely, and after 12 hours on the charger it would read ~11.5 volts, but then drop .1 volts every 30 seconds until it stabilized around 10.5 volts again.

Keep the batteries charged to at least 12-12.3 volts at all times. If you just leave them in storage like we did, check them every month with a multimeter and make sure they're in a healthy range.