Rules Change I Would Like to See - Batteries

[GeeTwo]

Originally Posted by Michael Hill

I would suggest against a USB converter because you're really only guaranteed 500 mA. ... The power is often really ugly ...

Many of the 12V converters feature a 2.1A port and a 1.0A port, which is enough for a pi. You can always add a couple of capacitors (it's a custom circuit) to clean it of if necessary. Our preferred method is still the VRM or other robust, regulated DC-to-DC converter. Jaci's bottom line is right on the money:

Originally Posted by Jaci

FRC Robots have a pretty big supply of power going to them as is, do we really need more?

Remember, in addition to the battery, we can (in most recent years, anyway) have pre-charged pneumatics tanks, pre-wound springs, and gravitational potential energy. (R35 A, C, and B respectively in 2016.)

Finally, If you really want that separate USB battery-power, charge up an old laptop, and power your pi off its USB port. There's no rule that says you have to turn the laptop on, much less do any processing on it. If you can use a classmate from a KoP, you won't even have to list any dollar cost in the BoM.

[FrankJ]

As I see it. The problem the second battery solves is not losing your sensors and CPU from brown outs. The old (pre 2009) control system had a battery for this purpose because a brown out would cause a loss of control without disabling the robot. A second control power battery Powering the Rio and radio along with other custom circuits would solve a lot of issues. It would also add cost and complexity to the robot.

Would another possibility for the auxiliary processing be the android system used in FTC? The come with batteries and meet the COTs definition.

[GreyingJay]

A cool idea, but I think the VRM (or a second or third VRM as needed) would do the trick.

We powered a Pi and an IP camera (and its LED ring light) off the VRM on our competition robot. On our practice bot, where we were a little less, uh, picky, we plugged the Pi into the USB port on the RoboRio.

[David Lame]

Originally Posted by Peter Johnson

Exactly. There are safety concerns as well given the prevalence of lithium ion chemistry batteries. You do NOT want a large one of those punctured or shorted. Cell phones and Kangaroos have pretty small batteries, and laptops are typically above the $400 cost limit (or considered too heavy). Punctures in even small LiPo batteries can be quite destructive, and a large lithium ion battery on a FRC robot sounds like a really bad idea when DC to DC converters (or doing vision processing on the driver station) are perfectly viable alternatives.

Well, that's a pretty compelling argument against my proposal. If there's a genuine safety concern, that pretty much trumps everything else.

The DC-DC converter plan seems like a better idea.

[FrankJ]

The safety aspect can be dealt with fairly easily. Cost and complexity still remain. The battery powered tool industry has pretty much gone to Li ion for everything except the bottom line tools. They get badly abused and have a low risk of fire/explosions. First could pick one or two commercial solutions and restrict maximum current draw and require specific chargers.

Another option for Arduino and PIs is somebody to package it with a battery and case. As long a it a company and they make it available for sale, it becomes a legal COTs device. (insert the usual future rules disclaimer here). Make it nice enough and maybe AndyMark would stock it for you.

[GreyingJay]

Having a separate battery isn't without its own concerns. Assuming this became legal, you just know there will end up being a team somewhere, sometime that will be kicking themselves for losing a key match because they forgot to charge the battery pack powering their vision processing system.

[marshall]

Hey look! It's a raspberry pi with a battery: https://www.sparkfun.com/products/13896

Ok, seriously, I agree with OP that this is a topic that needs to be dealt with.

My suggested rule change is simple though. Just enable teams to use all batteries outside of the standard robot battery provided they do not interfere with the control pathways for any motors, they can be removed and disconnected quickly/easily, and they do not appear to be unsafe to a reasonably astute observer (no exposed wires, held securely, can't be easily punctured, well protected, etc).

Originally Posted by Gray beards of CD

Marshall, you fool, you'll cause the inspectors a lot more work and make robots less safe to operate.

I don't think my suggestion will do either personally and it *might* just help a lot of teams who are struggling to deal with power-hungry games that demand power-hungry drivetrains and power-hungry mechanisms and power-hungry co-processor vision systems. I dare say, it might even inspire some students.

For one, enabling the use of all batteries means the inspectors don't have to look at an approved list or deal with the currently ambiguous ruling of only allowing non-standard batteries that are "integral to" a COTS computing device.... which by the way, I'd like to know if this flashlight (http://www.lightmalls.com/nextorch-p...4aAvW 98P8HAQ) counts as a COTS computing device since it is programmable.

Let's talk safety with alternative battery sources. If the concern is that something is going to catch fire then coin cell batteries and USB power supplies aren't likely to do it. I'm not saying they can't but they are common components (Sorry FRC fans but those crappy Chinese USB power supplies are a lot more common than FRC batteries) and I suspect the likelyhood of a fire is about the same as the chances of one from the standard robot battery we all know and love so can we ignore this facet of safety and move on? Not to mention that the same crappy Chinese batteries are legal provided they are "integral to" a COTS computing device.

The real issue/fear is that a robot or robot mechanism will remain powered up and running. I believe that if the team can demonstrate to an inspector that the power source does not interface with the power for a motorized mechanism or drivetrain then it should be legal. I believe teams already have to do this if they have an "integral" power supply for a COTS computing device on board... and if they don't then they should.

Also, I want a ruling about super capacitors while we're at it. They are circuit components and not batteries so they are legal for keeping a raspberry pi powered right?

While I disagree with the way the OP worded his initial post, this issue is a sore spot for me as well and I do think FRC should address it in a manner similar to the "allow but educate" style that they have adopted in the recent years. Come on KOP team, Frank, and LRIs... how about showing some love for additional power sources for computing devices?

[Joe Ross]

Originally Posted by Jaci

While we're at it, I think it's worth a mention that you are allowed up to 3 Additional VRM units on your robot according to R48 of the 2016 Manual.

That's not what that rule means. It gives you permission to break the one wago one load rule with up to 3 VRMs. It doesn't limit you to 3 additional VRMs, you could have as many as you want limited by the number of 20amp breaker slots there are * 3 VRMs.

[asid61]

Originally Posted by marshall

Let's talk safety with alternative battery sources. If the concern is that something is going to catch fire then coin cell batteries and USB power supplies aren't likely to do it. I'm not saying they can't but they are common components (Sorry FRC fans but those crappy Chinese USB power supplies are a lot more common than FRC batteries) and I suspect the likelyhood of a fire is about the same as the chances of one from the standard robot battery we all know and love so can we ignore this facet of safety and move on? Not to mention that the same crappy Chinese batteries are legal provided they are "integral to" a COTS computing device.

Coin cells aren't a concern as much as the others. If we allow even small USB li-ion packs, then what's to stop somebody from manufacturing a 60c lipo pack that can output 10 amps through the USB port? And that's not even including the inherent risk of cheapo battery packs that do catch on fir sometimes due to internal shorts. It's a lot safer just to use the existing battery which has proven to be extremely robust and safe IMO than to risk unknown, possibly dangerous components. The safest solution to avoiding sensor issues and brownout is just good power management. Unfortunately, that's definitely limiting, but safety is #1.
If FIRST partnered with Samsung or another reliable company to supply teams with a FIRST legal battery pack, that would be a good solution to the problem without allowing weird loopholes or dangers.

[ASD20]

Originally Posted by marshall

I don't think my suggestion will do either personally and it *might* just help a lot of teams who are struggling to deal with power-hungry games that demand power-hungry drivetrains and power-hungry mechanisms and power-hungry co-processor vision systems. I dare say, it might even inspire some students.

I don't think powering your 10W raspberry pi off a separate battery is really going to noticeably reduce the power consumption of your 6-CIM drive robot. While I am aware that there are much more power hungry co-processors out there and that is probably what you are referring to, none of them come close to 337W. Either way, the GDC has changed a lot of rules over the past few seasons encouraging teams to understand the power limitations of their robot and to design accordingly (less motor count limits, getting rid of max servo power (kind of)). Just like you shouldn't power your drive train off of 6 CIMs and 10 miniCIMs even though you can (at least based on motor limits and PDP slots), if that vision system really wrecks your power consumption, maybe you should select something that is less power-hungry or reduce your power consumption elsewhere on your robot.

[GeeTwo]

Originally Posted by Gray beards of CD

Marshall, you fool, you'll cause the inspectors a lot more work and make robots less safe to operate.

Hey, that's profiling - and OBTW, my beard isn't gray, it's almost white, except when I dye it green ;->.

More seriously, inspection is already a challenge for many inspectors; there should be a better reason than this to make it more difficult. If FRC can find a standard 5V power source for which they can provide a concise list or (even better) get something donated as part of the KoP, wonderful! Otherwise, this is (IMHO) a pound of solution for an ounce of problem.

[marshall]

Originally Posted by ASD20

I don't think powering your 10W raspberry pi off a separate battery is really going to noticeably reduce the power consumption of your 6-CIM drive robot.

It removes the hassle of a brown out by enabling two different and disconnected power systems so one does not interfere with the other. It's pretty similar to the way some vehicle power systems are designed.

Originally Posted by asid61

Coin cells aren't a concern as much as the others.

They are a problem though because they are currently illegal based on the rules. And why aren't they a concern? I've seen them go boom the same way I've seen LiPos go boom.

Originally Posted by asid61

If we allow even small USB li-ion packs, then what's to stop somebody from manufacturing a 60c lipo pack that can output 10 amps through the USB port?

Nothing other than the USB spec but you can dodge the spec. USB C is rated for 5 amps continuous and I'm not sure about surge but something tells me it could handle it. What's wrong with pulling 10 amps from another power source though? Is there something inherently dangerous about 10 amps? Doesn't the existing battery allow me to pull 10 amps?

Again, the safety concerns come from something going boom or something moving when it shouldn't be. Or maybe you are worried about someone being shocked? Either way, all of these can happen and have happened with the existing battery.

Originally Posted by asid61

And that's not even including the inherent risk of cheapo battery packs that do catch on fir sometimes due to internal shorts. It's a lot safer just to use the existing battery which has proven to be extremely robust and safe IMO than to risk unknown, possibly dangerous components.

There is no inherent risk that is not already present with existing batteries and as I've already pointed out, these cheap battery packs are WAYYY more common than FRC batteries and many people seem to be using them everyday without issue to charge their cell phones.

Originally Posted by asid61

The safest solution to avoiding sensor issues and brownout is just good power management. Unfortunately, that's definitely limiting, but safety is #1.

While safety might be #1, making it easier on teams to do cool stuff should be #2 or maybe #3. Enabling teams to run co-processors without worry of brownouts and similar makes it easier on the teams to do cool stuff.

Originally Posted by asid61

If FIRST partnered with Samsung or another reliable company to supply teams with a FIRST legal battery pack, that would be a good solution to the problem without allowing weird loopholes or dangers.

[sarcasm]Yes, because partnering with another company to deliver parts is just that simple and that has never produced supply problems for FRC teams in the past...[/sarcasm] It also does allow weird loopholes and dangers... the part could become obsolete or it could have a manufacturing defect (*cough* white exploding tanks *cough*). Just because you think a company is reputable doesn't mean they are impervious to turning out a malfunctioning product.

Originally Posted by GeeTwo

More seriously, inspection is already a challenge for many inspectors; there should be a better reason than this to make it more difficult. If FRC can find a standard 5V power source for which they can provide a concise list or (even better) get something donated as part of the KoP, wonderful! Otherwise, this is (IMHO) a pound of solution for an ounce of problem.

Inspection is a challenge and I'm very cognizant of that. So, instead of training the inspectors on a particular part, train them to look at the control system and power pathways for the motors to ensure they are not being interfered with from a USB power source... I'm not saying it will be as simple as asking the team to point out any onboard power sources other than the big robot battery but you could and then verify they aren't plugged into any motors or motor controllers.

You guys need to get real about this though. If you actually want to see this rule changed then suggesting that FIRST partner with another supplier for it and make rules about requiring specific part numbers just makes it more difficult, not easier. It puts the burden on the FRC folks to track down parts, get them donated, include them in the kit, write specific rules about them, etc. That's a lot of work for some already overworked people.

An alternative, as I have suggested, is to change the existing rule to fall in line with the example that is already allowed under the batteries integral to COTS computing devices. No one is checking those specific devices or batteries but they are typically checked to make sure they aren't powering any moving assemblies on the robot.

Also none of you addressed the existing loop holes that I already pointed out including a flashlight that could be considered a COTS computing device and using super capacitors, which I'm more worried about other teams trying to use than I am a cheap LiPo pack (I'm not actually worried, I encourage it, go use them because they are legal under the existing rules!). It is possible to make all of these items secure and safe though.

And with that I'm done with this thread. I could argue with you guys all day about this. I've offered up a solution that makes sense and should make it easy. Stop arguing and actually think about the problem for a while. What I've said isn't crazy talk and is a good way to solve this.

[ASD20]

Originally Posted by marshall

It removes the hassle of a brown out by enabling two different and disconnected power systems so one does not interfere with the other. It's pretty similar to the way some vehicle power systems are designed.

Ok, I do agree a separate power source will limit the impact a brownout will have on your robot, but I am still of the belief that designing to avoid brownouts is just part of the game and that FRC should solve the actual problem by better educating teams on power consumption, rather than just helping one of the symptoms.

[FrankJ]

Originally Posted by ASD20

Ok, I do agree a separate power source will limit the impact a brownout will have on your robot, but I am still of the belief that designing to avoid brownouts is just part of the game and that FRC should solve the actual problem by better educating teams on power consumption, rather than just helping one of the symptoms.

While it is certainly part of the current rules and you have to allow for it...
My opinion is it would be a better game if you didn't have to deal with controls brown out as it is now. As a complete tangent, an industrial design that had these issues would either separate control & power energy or make the energy source big enough so that is wasn't a issue.

With the current rules, a super capacitor would likely make the robot fail the power off test on the robot inspection check list.

[techhelpbb]

If you make a COTS device that consists of the battery, charger and device you can work this rules set without major changes. I've brought this up before elsewhere on ChiefDelphi and passed that concept around with FIRST engineering a few times. (I reread this topic and note that FrankJ brought this up previously).

So it's possible to make a bundled Raspberry Pi based device with a battery and sell it as a unit COTS. You must sell it to the general public essentially engineered with safety in mind. So the battery boards for the Raspberry Pi do not really cover this because they are not bundled with the system or even enclosed.

The risk of *any* lithium based battery is already present because FIRST allows laptops with batteries on the robots, again they could always change that next year, but FRC11 has used a laptop with battery several times.

Once the risk exists already it's really hard to argue we can't regulate the hole.