Battery Mounting 2020

Our team was wondering if mounting a battery securely while mounted to the underside of an elevated platform was legal. Please site if there is a rule against this if you can find a restriction of this application of a battery mount.

Thank you, and have a good day.

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Hard to say without a picture but nothing you said sounds specifically illegal, I have passed number of teams with their batteries not mounted on their base plate.

The relevant rule is R37.

R37. The ROBOT battery must be secured such that it will not dislodge during vigorous ROBOT interaction including if the ROBOT is turned over or placed in any arbitrary orientation.

As long as your battery is attached securely in any orientation, you should be fine. You probably want to keep your battery low on the robot to lower your center of gravity, but there is no rule that requires it.

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Certainly! The battery mount must work in any orientation anyway, so having it start in a non-traditional orientation is OK.

Thank you for everyone who responded. The speed at which this question was answered was astonishing. We will take into consideration that the mounting of the battery can be placed anywhere, but needs to be secure, as in accordance of R37.
Thank you again to everyone who responded!

In addition to the mounting system you use being legal, it should also be convenient for you to replace the battery quickly and easily (for your own sanity).

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Absolutely! While it’s not a rule, the threshold for pain in changing an FRC battery should be significantly smaller than the threshold for a bumper swap. If it takes more than a minute the third time you do it, you’ll wish you’d made it easier.

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A slow battery swap once cost my team dearly. There’s no experience like watching your robot obviously run out of power because your drive team didn’t have time to both charge pneumatics and change battery…when you had to win that match to extend your season.

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Okay, I’ll be the voice of caution here.

I once was mentoring a team that elected to put their battery mount upside down as you’re proposing, and we had an inspector who would not let it fly. I was involved in the decision for how to mount it, and I know it was rock solid. The whole depth of the battery was supported—basically five full faces of the prism surrounding the battery—it did not hang below the frame, and the bottom side was supported with two redundant straps. But nevertheless, our inspector didn’t like it and wanted it changed.

I’m not saying I think it’s a bad idea, but be prepared that some inspectors may not see it the same way.

At that point you probably should have gone to the LRI. If there wasn’t anything illegal about it, the inspector should have nothing to say. Only the LRI has the authority to declare something illegal due to a safety concern.

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Agreed.

My usual method for inspecting the battery mounts’ security was to grab the loaded battery and try to shake and jostle it out of the mounts. If it moved more than a little bit, I would mention that, but I would phrase it as a suggestion (along with “This is really likely to come out on the field, and you don’t want that”). If it came out, the team had to fix it.

There seems to be two philosophies regarding battery mounting. One is to ensure that the battery is tightly held in place like @EricH describes. The other interpretation of “secure” is to drop the battery into a 5-sided box that prevents the battery from sliding around but there is no 6th side to prevent the battery from falling out if the robot flipped over. I have seen some pretty prominent teams doing it the second way.

Just don’t mount your battery upside down…

In the second link you provided, it states that the battery terminal was driven into the battery. That can happen no matter what orientation the battery is mounted in, either by the battery shifting position or something moving and pushing against the terminal. If the battery was mounted sufficiently securely AND with adequate clearance around the terminals, the fire would not have happened.

The OP did not mention the battery being mounted upside down, had they I would have highly recommend against it.

There are two reason for this. First in the unlikely case your mounting method fails the battery would fall leads first which may cause a leak, short and/or fire. Secondly not all batteries are as sealed as others and you wouldn’t want acid leaking on your robot or the field.

I just re-read R37 and it specifically states that the battery “will not dislodge during vigorous ROBOT interaction including if the ROBOT is turned over or placed in any arbitrary orientation.” Emphasis is mine.

On teams I have worked with, we mount the battery securely enough that one can lift one end of the robot off the floor by grabbing the battery by the “handle” and lifting up.

By battery “handle” I assume you mean the leads, correct? :slight_smile:

I’ll leave now…

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Miller,
My first thought when reading your post is that you are asking about mounting the battery under the robot. OIf that is the case, please reconsider your design.

I didn’t mean what you think I did. By “upside down,” and I guess I could have been more careful with my words, I meant what the OP was referring to—the direction of egress for the battery being downward, not the leads being on the bottom. That is why I phrased it as the mount being upside down, not the battery being upside down.

Or don’t! Assuming ample ground clearance, a 6-sided enclosure that hangs from a solid brainpan would be very legal and very cool. You’ll just have to tip your robot over to change it every time, but it’s workable.

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