OP: This is the point of how to build a robust system. It should not have to rely on a maximum (and potentially illegally reached) voltage level to be effective. A robust solution would operate at less than perfect voltage and be able to compensate when the charge is higher.

Re: Be aware of battery and charger inconsistencies!
 

not when the force you need is only available with doing just that. As i mentioned before we have to slam our kicker with a mostly full battery to make it from the white zone. There is no overhead here. We have tried different transmission ratios and weights. higher ratio we don't develop the speed we need, lower ratio we don't have enough force to achieve the speed, etc. We can have a margin closer up, but what good does that do us if we want to shoot from further away? there may be some way to achieve all the goals and have this overhead but we arn't a team with two dozen engineers and a NASA machine shop. We just get a robot together that works and hopefully get it done by bag day. You should understand these types of limitations if you are part of an FRC team. You just have to work within the limitations and don't have the time or resources to redesign the whole system

Re: Be aware of battery and charger inconsistencies!
 

we just try to build a good enough working system, robustness is an afterthought. These types of things are easy to say but until you are up until midnight on bag day trying desperately to finish a robot you just won't understand what it means that you're out of time and there's nothing you can do about it and that there isn't anything more you could have done during the season simply because you don't have the resources. You can say all you want how there is a better more robust way to do it but frankly that just isn't even an option for most teams. They just try to make something work, not build a mars rover.

Also it's impossible for these chargers to charge the batteries to illegal voltages. As i have stated over and over, it's not about the current, it's not about the voltage, it's about the CONSISTENCY. the batteries are only at 13.5V when freshly pulled off the charger. They can't overcharge the batteries. and we will use them in a way which is within ALL rules anyway. I really don't think most people in this thread have any idea how batteries and chargers actually work. As someone else stated it's like saying a Ferrari is dangerous and shouldn't be allowed to be driven on the street just because it can easily break the speed limit even though when properly used it will fall within all laws(rules)

Re: Be aware of battery and charger inconsistencies!
 

didn't ask yet don't have the team login

Re: Be aware of battery and charger inconsistencies!
 

What about dremels? they can throw sparks when used on steel. As far as I know their usage is permitted though, just need to be used on materials that don't throw sparks like aluminum or plastics.

Re: Be aware of battery and charger inconsistencies!
 

Sanelss, if a cop pulls you over for going 65 in a 45 zone, are you going to protest that the speed limit is too low, and needs to be raised, and besides, you aren't speeding?


If your answer is no, then I suggest that you just got pulled over and protested on BOTH points. I highly recommend that you take the first step you should take when you find yourself in a hole: stop digging. By now, I would guess that half the inspectors in your event(s) have figured out which is the first pit to check for chargers that are illegal, and will be busy tipping off the other half on the first day of said event(s).

If your answer is yes, then I suggest reconsidering that mode of operation.



I could be even more blunt, but in order to save as much face as possible for all concerned, I will refrain from going that route.

Re: Be aware of battery and charger inconsistencies!
 

Yet in this case the cop is putting you over for going 45mph because your car can go 60mph and demands that you need a new car that has a max speed of 45mph, despite the fact that you were clearly going 45mph.


Edit:
Also, just though of something that could remove the chance of argument and burden of proof with inspectors, if you would to wire the chargers to the batteries with a 6amp slow blow fuse, wouldn't that be enough to show that the batteries are not being charged above the recommend rate?

Re: Be aware of battery and charger inconsistencies!
 

From what I've been hearing, the car was going 65 after going 45 most of the length of the stretch. Sorry, that's a no-go. You can argue the "can go" argument all you like, but the radar don't lie.


Let me make something clear to y'all. The rule is the rule is the rule is the rule. Because it is a rule, it is enforced, regardless of how dumb, idiotic, or moronic it may seem. If you violate the rule, and you get caught, you can expect the penalty. Again, regardless of how dumb it seems. (It's not like I have prior experience with seeing this happen or anything, I've only seen this general class of rule or ruling an average of once per year from a certain group of people...)

Re: Be aware of battery and charger inconsistencies!
 

From what I understand of their setup, they are using bulk chargers to charge the battery most of the way, then the move to the other chargers to top off/trickle charge at a low amperage.
Using the same example, you would be going at 45 with a car that only goes 45 for most of the trip, then switching to a car that is going 5mph but can go 65 for the rest of the trip.

Legally that would satisfy all of the rules.

The issue seems to come from "what if the other charger goes higher then 6 amps, for whatever reason, even though it shouldn't" which is where I would recommend fusing the charger with a 6 amp slow blow fuse, to enforce a limit. So it CAN NOT charge at a rate more then 6 amps and makes inspectors happy.

Re: Be aware of battery and charger inconsistencies!
 

But consider this: they are getting a competitive advantage out of it. Imagine that you're in a (distance) race, and most cars go 55 (most efficient speed, for a car) the whole way until they run out of fuel. But this one car goes 55 until it runs out of fuel... and pulls out a 1-gallon gas can, dumps it in their tank, and drives another 30 or so miles beyond the rest of 'em--because they pulled out that extra gas can--which may or may not be legal (we haven't clarified that yet, because SOMEONE hasn't asked Q&A!).


Again, the rule will be enforced. No amount of whining and complaining about how your entire design revolves around this particular setup will change that. (BTW, that's how this thread struck me last night--a bunch of whining and complaining and "I'm not doing anything wrong, see this other example" from some folks.)


One thing about that slow blow fuse: You'd have to show that you did that particular modification safely. Otherwise, the charger would be sent out of the pit not under being a potentially illegal charger, but under being a safety hazard.

Re: Be aware of battery and charger inconsistencies!
 

Any battery charger can be used, provided it does not charger higher then the rated charge rate of the battery, some battery chargers are better, some are worse. Could a team find a charger had the same effect and is rated less then 6 amps? Most probably yes. Would it be legal? Yes.

Can a team buy several of every legal battery, load test them, find the best model. Then buy 50 - 100 of that model and test them all so they only use the best 10? Is that an advantage? Yes. Is it legal? Yes.

The rule is not to charge at a rate greater then X, there is no rule on the chargers themselves.

Also, do you change the output leads on battery chargers? I know must teams do, and I don't see how adding a fuse is much more unsafe.
Also I will point you to teams using custom made cases for their chargers.

Re: Be aware of battery and charger inconsistencies!
 

I would be quite confident in saying that if the Q&A didn't say otherwise, your robot would not pass inspection until you removed the chargers from your pits.

Since this seems to be getting to the point where all the arguments are becoming circular, it would be nice if someone asked the Q&A and closed this thread (or just close the thread, OP can make a new one when he gets an answer from Q&A).

Re: Be aware of battery and charger inconsistencies!
 

except i'm only going 30mph in a 40mph zone. I just have a car that can go 200. There is no rule that states which cars you can or can't use or what the top speed of a car can be, just a speed limit. and i will happily abide by that speed limit. you guys keep thinking some rule is being broken. IT'S NOT. we have equipment that can be used to break rules, but we AREN'T using them in such way. so your analogy is completely flawed. the inspectors can check all they want. Not a single rule is being broken.

you guys can be as blent and uptight about it as you want, but it states very clearly what the rules are and i stated very clearly of how we will abide by them. It makes no difference to me if others do or don't like it or if some inspector thinks there is a problem with it when there isn't...NO RULES ARE BEING BROKEN, WE ARE NOT USING ILLEGAL CHARGERS. is that blunt enough? The inspector guy said we can't use them, but there is not a single rule against what types of chargers, only charge current limits.

I will post in the Q&A when I can but I don't have the team login to do so at this moment.

Re: Be aware of battery and charger inconsistencies!
 

Let me put something straight, in BLACK and WHITE: The inspector says you cannot use them, and you use them ANYWAY, then you need a CLEAR RULE that says that the inspector in question is wrong, applied by the LEAD ROBOT INSPECTOR at the event, to use them. In other words, you need to prove the inspector wrong, by the rules. Guess what, you can't. On the other hand, you can't necessarily be proven wrong--but that means that you need to make 1000% sure that you are following the directive of the Safety Manual--which that charger doesn't help with. (Did I mention that this directive about the charger is coming through the LRI?)

The other factor here is the charger type. It's been brought up before--but charging this type of battery with a charger meant for car batteries (these are motorcycle batteries) could present a safety risk--and a safety risk that can be avoided is TO be avoided, especially in the pits.



I remind you that if the lead robot inspector rules that you're charging your batteries with a charger deemed illegal, then they can refuse to pass you at inspection. No pass, no play. No play, no rankings, no standings, no Saturday afternoon play. All because someone didn't know the difference between being stubborn and being obstinate. It's happened before, though under clearer circumstances.

Incidentally, I can think of a quicker, though obviously not official method. I'll see if I can get a particular person to weigh in--an electronics guy who happens to have an awful lot of clout in what actually gets inspected.

Re: Be aware of battery and charger inconsistencies!
 

As someone mentioned we can fuse it for 6A and that should remove all doubt from our situation and fallowing rules. From the previous linked documentation there is absolutely no danger even if it were to charged at 15A with these chargers, there simply is no safety risk other than a couple people's fear of what they don't have knowledge of. Well no more safety risk than any other charger that is. This is not a valid reason to restrict equipment when there is information showing it's perfectly reasonably safe.

I also don't see how a robot inspector can deem something illegal when he has no rules to base it off of and how the equipment you use can prevent a robot's inspection. The tools you use to maintain a robot have nothing to do with robot inspection requirements. He may state something is unnecessarily unsafe and needs to be addressed but he can't just outright deem something illegal of his own will when we can prove the opposite. Or maybe they have some secret powers i'm not aware of.

I know i'm being stubborn, both because our season depends on it and because i honestly don't think we're in the wrong. If it wasn't such a critical thing I would just let it go but it's not something we can just let go without having a dramatic and devastating effect on us. It's either we can use these for trickle which is within all rules, or we can't do 3 ball autonomous and we will probably miss most shots because of battery inconsistencies.

So our two options are find a way to use these, or give up hope on doing well this season since we know full well we can't perform if we can't use something better than our old chargers. I don't think i'm doing anything different than anyone else would.

I'll post for an official answer the soonest opportunity I have I just haven't had that opportunity yet.