minibot battery

just saw this, Detroit regional…](

what are peoples thoughts (on the legality of the battery)?

According to this Q&A this is expressly forbidden.

01-25-2011, 07:25 PM
Junior Member

Join Date: Dec 2010
Posts: 5
Minibot battery modification
Is it permitted to separate the cells of the minibot battery (keeping the electrical configuration intact)?

01-31-2011, 03:39 PM
Game Design Committee

Join Date: Jan 2006
Posts: 2,762
Re: Minibot battery modification
This would be a violation of R92-C.

no kidding. heres another shot of it:](20110318 171618 _MG_1934 | Daniel Ernst | Flickr)

Assuming that is the two halves of the actual tetrix battery it is legal. No where in the Minibot rules does it forbid modification of the battery.

Edit: How is it a violation of 92c? It is not more than 1 battery.

If that’s two of the allowed batteries, then one of them is *definitely *illegal. If it’s one split in half, that would probably place it under the “illegal” category due to it no longer being identical to the legal battery. <R92-C> bans more than one battery and non-identical batteries (save the fuse replacement).

You might be able to do it if one of the batteries was not connected, but that is still a violation of <R92-C>.

I’m not going to ask whose it was, or who let it onto the field. But if they read this, then I might suggest replacing one battery with an appropriate mass of an allowed material–and the other with a fully legal battery–or moving the battery location.

They let that compete?

Don’t ask me, the GDC has spoken.

if it is allegle y did thay let it on::rtm::

There is a single word in <R92-C> that can make the difference between legal and illegal here. That word is “identical”. The battery, once split into halves, is no longer identical to the battery as purchased. Hence, it’s not legal to use.

I think that’s what the GDC was saying regarding separating the cells.

I agree that it SHOULDN’T be because it just looks like it should be illegal but I couldn’t find a rule against it.

English please…

It is possible they didn’t find a rule against it (I didn’t when I looked).

They didn’t find a rule against it. However, that’s because they didn’t look in the Q&A. See Martin’s post. That’s not the rule… but it’s supposed to be how the rule is called.

Now, how separating a cells is a violation is the tough part. I would suspect that the rule calling for an identical battery is why it’s a violation. Not sure how an electrically unchanged battery being separated while remaining electrically the same is a violation–electrically, it should be identical–but, nonetheless, that is the call the GDC has chosen to make, and as such is the ruling that needs to be listened to.

Oh, and If I can translate royal robotics’ post: “if it is illegal why did they let it on ::rtm::” (Next up after proper English spelling will be proper English capitalization and punctuation, which for now is left as an exercise for those that need the practice.)

It’s quite possible that the inspectors simply missed that it was illegal, and nobody complained at the event. This happens from time to time; there have been robots rebuilt at the Championship because they were not in compliance with the rules, yet they had passed regional inspection. I’ve had to reject stuff that non-official inspections had said was okay. It happens.

Martin, Eric, et al,

The problem is that FIRST did not publish a search-able, consolidated Q&A this year and most events did not have internet access available to the inspectors.

If a team presented a Q&A to support their claim to legality, it was accepted. However, if an inspector “remembered” seeing a Q&A stating something was illegal, the LRI was forced to rule in favor of the team.

As an inspector, similar rule “violations” happened to me twice in FL and I was forced to let the violations go in favor of the teams because the rules did not expressly forbid it.


Like what? Just curious to know because I really never remember hearing anything at the regional.


Why should you have? Without a comprehensive Q&A, the rulings went in favor of the team…

For example, what if a team had a minibot magnet with an integral metal cover? Many COTS magnets, such as a cabinet latch or some refrigerator magnets, are sold this way… This GDC insight may have been overlooked in favor of the team…

Without the Q&A, the LRI is forced to give the team the benefit of the doubt.

Teams are likely to print out Q&As that support their design decisions but not those which point out their “illegality”. I know of no inspectors that print out over 300 GDC “gems” and, even if they did, there is no time to manually search that paper stack.

An electronically searchable database (like this one from last year) is the only solution and FIRST decided not to provide these this year…

We do the best with what we have…


So what’s the difference between splitting the battery into two 6v packs and running it in series to get 12v or removing/changing the gearbox from the ftc gearmotor?

One is legal, the other isn’t. It isn’t really something the GDC is likely to give their reasoning for.

Please see page 67. I believe you will find an answer there as well as other places in the official GDC consolidated response to questions.

Please also see Update 5. In addition, some teams came to regional events with a minibot battery wrapped in transparent wrapping. The only official battery is the Tetrix battery wrapped in the black wrapping material.

Good luck, everyone.

Q_A_Forum-03092011.pdf (336 KB)

Q_A_Forum-03092011.pdf (336 KB)

May I ask where this document came from? I traded emails with Al Skierkiewicz on the 9th and it did not exist to his knowledge. It was not available at FL either…

I just checked the First site Manual, Team updates and KOP pages and saw nothing.

Could you provide a link?


There is a good reason to make separating the battery illegal. The heavy duty shrink wrap is for insulation as well as holding the batteries together. If you’ve dissected one of these “sub C” style of battery packs you’ll find that the the cells are arranged with half of the positive terminals “up” and half of them “down” so it isn’t hard to create a short circuit creating a “loop” between 2 or more batteries. Allowing that shrink wrap to be removed creates the need to have a standard as to what constitutes appropriate re-insulation thus putting additional demands on the inspectors.

I did notice in the Cascade/Olympic pits on Fri at least one minibot go by that had a clear wrap which made me think it wasn’t a legal battery.

All a clear wrap means is that it is an older Tetrix battery.