Rattling Battery?

[sanddrag]

Has anyone ever had a battery rattle inside? I have a Genesis battery that sounds like it has plastic pellets inside when you shake it, like a musical maraca. What causes this?

[philso]

We use several pallets of the Genesis batteries per week in the UPS' we build at work. I have never heard of such a failure mode. The only think I can think of is if the battery was dropped and part of the internal structure that holds the lead plates in place has broken, allowing the lead plates or the broken bits of plastic to rattle around inside.

[protoserge]

I'd mark it damaged and recycle it.

Are you absolutely sure the screws/standoffs on the terminals aren't loose?

[sanddrag]

Originally Posted by protoserge

Are you absolutely sure the screws/standoffs on the terminals aren't loose?

Affirmative.

[FrankJ]

Anything that stores energy has the potential of dangerous failure modes. I would call it broken and recycle it. At the very least I would only use it in a static application and not on a moving robot.

[philso]

If the screws or standoffs on the terminals are not loose, then the rattling is internal. Without knowing the internals details of the battery housing, I would do as several of the other people in this thread suggest, send it to recycling. If it is really just an "unimportant" bit of plastic rattling around, you might not have a problem. If that bit of plastic was holding the lead plates in place, the plates might end up shorting out at some point, maybe much later. Such a short can cause the battery to explode and spray acid everywhere. It is just not worth the risk, even if you are on a "low resource" team.

[protoserge]

Originally Posted by philso

It is just not worth the risk, even if you are on a "low resource" team.

The newer rules make batteries much more affordable (~$25-35 shipped for some) so I would find it hard to use the "limited resource team" line.

[sanddrag]

Originally Posted by protoserge

The newer rules make batteries much more affordable (~$25-35 shipped for some) so I would find it hard to use the "limited resource team" line.

While we're on the topic, what is your source for these $25-$35 shipped batteries? Also, given all the various choices in batteries now, is there a clear "best" battery in terms of performance?

[GreyingJay]

Do we know for sure that the battery equivalency rule introduced in 2015 is here to stay for 2016?

[protoserge]

Originally Posted by sanddrag

While we're on the topic, what is your source for these $25-$35 shipped batteries? Also, given all the various choices in batteries now, is there a clear "best" battery in terms of performance?

Check out Battery Sharks for the Sigmastek (sp?). 1 battery 2-pack. If you exercise the single battery without shipping option, you can get 4 for $115ish shipped (at least to my zip code).

I don't expect a rule change on this, but buying cheaper 12V batteries should be on all teams' radar for practice and non-competition use. Proper battery management will get at least 4 seasons of use.

There is no real difference between the batteries in capacity or construction. When I was on 836, we ran several brands (MK, Genesys, National, Sigma/Battery Sharks) and they were pretty much identical in all regards using an accepted test procedure for batteries. adciv can probably provide more detail if you require it.

[Knufire]

We've been buying batteries direct from MK Battery for $37.50 shipped.

[protoserge]

Originally Posted by Knufire

We've been buying batteries direct from MK Battery for $37.50 shipped.

Good to know. Are you using a commercial customer account or just telling them you are a FIRST team?

[philso]

Originally Posted by protoserge

The newer rules make batteries much more affordable (~$25-35 shipped for some) so I would find it hard to use the "limited resource team" line.

Yes, the cost of batteries is not that high especially when considering the overall budget. My reference to "low resource" teams speaks more to a perception than reality; i.e. it's not worth it for any team to use a battery that might blow up.

[pilleya]

While I don't see there being a battery that is clearly better than others.

There are batteries which would be more suited to the abuse and the high current draw that FRC batteries typically face.

Some Battery manufactures supply intended use information with their batteries. I have found two different types of Panasonic Batteries online, both with similar capacity. The difference lies in their intended use. One battery use statement says "UPS, Security, Alarm, Instrument, Test Equipment, Medical Equipment;This model should be used for standby use only". Where as the other battery says "battery suitable for continuous cyclic usage such as golf buggies & mobility aids/motorised scooters."

Now, the difficult thing to consider is which of these fits FRC best. Typically batteries are charged and then not used for periods of time, then when it comes to events they are rapidly discharged and then recharged continuously. Would a battery intended for a UPS or a battery intended for something like a motorised scouter be superior?

Coming back to the actual intended thread topic, the Rattling Battery seems really strange. I would recommend recycling or disposing of it, it's just not worth the risk.

[Al Skierkiewicz]

Dave,
Generally there is nothing good about loose particles inside the battery. It is possible that someone dropped something on the cover over the pressure relief valves. Small pieces of plastic may have broken off.
It is also very likely, some of the internal plastic between cells has broken loose. If this is an AGM battery, there may not be any immediate danger. I would recycle before something occurs.
The pressure relief seals at the top of each cell I have seen are mostly rubber and would not rattle if they came loose.
Does the rattle appear restricted to the valve cover?