Battery Rules

[ICE_Bear]

Where are the battery rules in the Game Manual? I looked through the manual to try to find them, but I didn't find anything.

[EricH]

R31 has them.

[ICE_Bear]

From what I read, there's only one rule for how we mount the battery... Is that correct? Or is there a section or rule other than R33 about the mounting?

[EricH]

From what I read, there's only one rule for how we mount the battery... Is that correct? Or is there a section or rule other than R33 about the mounting?
That is correct.

I'll go a little more in-depth: Orientation (for use) doesn't really matter, though on the side or upright tends to be best. (For charging, upright is important.)

But what you're really after is making sure the battery doesn't move within the robot. Just using velcro might not do the trick; I know for a fact that duct tape is not going to be all that helpful. Many teams will build a battery box into their robot to hold it in one position, and then use velcro or a buckled strap to secure it down.

[ICE_Bear]

We have a mounting kit from Andymark that sits on it's side, would we be able to use that in a vertical position?

[ICE_Bear]

http://www.andymark.com/product-p/am-2939.htm

[EricH]

I don't see why you wouldn't be able to. How you do that, though, is up to you.

[ICE_Bear]

Thank you :)

[bdaroz]

We have a mounting kit from Andymark that sits on it's side, would we be able to use that in a vertical position?

We are doing exactly that this year - in fact the kit fits nicely in a spare piece of KoP Chassis C-Channel turned face down.

Disclaimer: Rookie Team - Rookie Mentor -- Assume I have no idea what I'm talking about. :)

[cbale2000]

That is correct.

I'll go a little more in-depth: Orientation (for use) doesn't really matter, though on the side or upright tends to be best.
(For charging, upright is important.)

Could you elaborate on this? Our current battery charger design has the batteries laying down. What is the downside of doing this? Do we have to completely redesign and rebuild our battery cart?

[nighterfighter]

Could you elaborate on this? Our current battery charger design has the batteries laying down. What is the downside of doing this? Do we have to completely redesign and rebuild our battery cart?

If the batteries need to vent when charging, they are designed to do so while sitting vertically.

[FrankJ]

Could you elaborate on this? Our current battery charger design has the batteries laying down. What is the downside of doing this? Do we have to completely redesign and rebuild our battery cart?

My preference is to charge upright. Truth is it really doesn't matter 99.9% of the time. My UPS has one of its batteries permanently upside down. The battery manufactures generally do not recommend this. Flat is OK. AGM & glass mat batteries have very little free liquid in them. Using a smart charger & charging at recommended charge rates is more important then battery orientation.

[rich2202]

We go through so many batteries that we would never think to charge the battery while on the robot. So orientation is not an issue for us.

Regarding the battery mounting rule:
R33 The ROBOT battery must be secured such that it will not dislodge should the ROBOT be turned over or placed in any arbitrary orientation.

"arbitrary orientation" includes turning the robot upside down. Basically, once secured, there is no way to remove the battery. All 6 sides of the battery must be restrained.

Some people use "compression" to hold the battery (squeeze the sides of the battery). I personally don't like it. I would much rather see a strap across the top.

[FrankJ]

Keep in mind going over the defenses loads the robot is many directions. Having the battery really secure is going to be way more important than in years past.

[philso]

Keep in mind going over the defenses loads the robot is many directions. Having the battery really secure is going to be way more important than in years past.

Would a robot that is E-Stopped because it's battery bounced out while crossing one of the DEFENSES be considered a Tortola?

[GeeTwo]

Would a robot that is E-Stopped because it's battery bounced out while crossing one of the DEFENSES be considered a Tortola?

Tortuga, but yes - see my bolded sentence from Dr. Joe's definitions:

There have been a few legal eagles asking for the definition of what it means to be "tortugaed*"

It is a little like art, in that we'll know it when we see it, but a good working definition is that a robot is tortugaed when it stuck or disabled while attempting to traverse or helping another robot traverse a defense. Stuck should be broadly interpreted.

Some examples:

if you flip over crossing the Chapel of Frost and you're technically not in the defense zone anymore but everyone knows that it was the defense that done you in. Of course, we're going to give you a tortuga for that.

If the Drawbridge thwaps your battery from its cradle and the field officials don't disable you until they see you dragging that 17AmpHours Anchor around the courtyard, again, you've been tortugaed my friend.

If your alliance partner gets stuck on the rock wall and you go over to try to give them a bump to save them only to have their flailing Sally Port arm reach into your robot and, horrors, turn off your main breaker, why, that's a tortuga for two right there!!!

If you are holding open the Sally Port and an alliance robot goes insane, pushes you against that very door after which their motors start smoking and they hit their e-stop and you spend the rest of the match unsuccessfully trying to get out from the pin they've put you in. Again, two tortugas will be awarded.

I hope this clears things up, even as it maddens the legalist in the FRC world.

Cheers,
Dr. Joe J.

*Yes, it's a verb now.

[vhcook]

Some people use "compression" to hold the battery (squeeze the sides of the battery). I personally don't like it. I would much rather see a strap across the top.

As an inspector, I would be highly reluctant to let a mounting like that through this season (or really any other, but particularly this season). A press fit battery isn't going to stay with the robot if you hit any defense in group B or D at speed.

[dradel]

The way I have looked at battery mounting is this.... Will the battery dislodge (fall out) if the robot is on one of its sides or upside down being shaken violently like another robot were trying to upright the tipped one.

If the answer is anything but no, keep working at securing the battery.

[cbale2000]

If the batteries need to vent when charging, they are designed to do so while sitting vertically.

So, if one were to have doors on their battery cart, but also have the cart ventilated (with fans or otherwise) to prevent thermal runaway, it should be ok?

[MrRoboSteve]

These straps (http://www.homedepot.com/p/VELCRO-brand-3-ft-x-2-in-Velstrap-Straps-2-Pack-90440ACS/202261929) are good for batteries.

I foresee more e-stops this year than last.

[BBaltrusch]

My preference is to charge upright. Truth is it really doesn't matter 99.9% of the time. My UPS has one of its batteries permanently upside down. The battery manufactures generally do not recommend this. Flat is OK. AGM & glass mat batteries have very little free liquid in them. Using a smart charger & charging at recommended charge rates is more important then battery orientation.

I would still charge upright if at all possible. Venting isn't really a concern with FRC batteries but gas pockets can be. At full charge ideally each cell has a plate of pure lead(Pb), one of pure lead oxide(PbO2), and sulfuric acid(H2SO4) as the electrolyte(in practice diluted with H2O). When you discharge both plates turn into lead sulfate(PbSO4), giving up electrons and creating more H2O. Sulfuric acid is completely soluble in water so that mixes just fine.

This is not true while charging. Hydrogen gas is created and there's a chance a pocket gets trapped against a portion of a plate that can't react with it. That portion doesn't charge, slightly reducing total capacity. Do this enough and you start real damage to the battery. This is negligible at trickle charge rates like a UPS sees, but we at FRC like to charge our batteries as quickly as allowed.