Battery Charger Restrictions

[Ian Kaplan]

Originally Posted by Andy A.

Do you happen to know for certain what the maximum charging current is?

It is possible to damage and even rupture this type of battery with excessive charging currents. This can be extraordinarily dangerous and, at a minimum, would result in a minor hazmat cleanup situation. You can imagine what the worse case scenario would be.

The manufacturer calls for a 2 amp charging current, for what it's worth. 6 amps is, through experience, safe but probably does the battery's lifespan no favors (oh well). Anything above 6 amps is considered dangerous. If the pit staff called your charger out it was either because

A: The maximum charging current was grossly in excess of 6 amps.

B: They felt that the maximum current draw of the charging station could overload the circuit it was connected to

C: They felt that the number of batteries, cables, and such in close proximity merited a safety hazard of its own.

Most of this is subjective (and my list isn't at all all inclusive) and in the end the pit staff and venue staff get broad authority if they feel they are acting to protect the safety of teams, public and venue. I'd guess they made a call along the lines of C. Maybe not fair, but without being there I couldn't fairly say. You handled it correctly though, so good on you and your team. I would suggest that, if you plan on attending another event this year you email the event coordinator to discuss the matter ahead of time. He/she can involve the necessary pit personal so, come game day, there is no confusion.

While I will let someone on my team talk about the specs of the charger, I can say that we used this charger at the New Jersey Regional with no problems.

[Tristan Lall]

As mentioned above, it's unlikely that a judge (they wear blue FIRST shirts) told you that. If you tell us what sort of shirt (colour and style) the volunteer was wearing, we can probably tell you what their responsibility was.

If it was a venue restriction, someone should have said so, in advance if at all possible. (I doubt it was actually a venue restriction.)

And no, there's no battery charger rule this year. (It used to be in "The Robot", which I always figured was a mistake—it belonged in "At The Events", unless the intention was to prohibit robots from using improperly-charged batteries, a prohibition which was never articulated in the old rule.)

[ebarker]

The charge rate issue has been covered in other threads with a post here on the max rates.

http://www.chiefdelphi.com/forums/sh...64&postcount=4

The Schumacher looks like a nice charger but the middle and high charge rates are not good for these batteries. At best it will shorten the life and worst cause a catastrophic failure and either way that is a lot of money burnt up in batteries.

[Andy A.]

Originally Posted by Ian Kaplan

While I will let someone on my team talk about the specs of the charger, I can say that we used this charger at the New Jersey Regional with no problems.

Just remember that what flies at one venue may not go over well at another. This is as old as FIRST (or, as old as multiple venue FIRST). The folks who were working at NJ probably aren't going to be at the same venue you are this week. And, as an aside, one of the least effective arguments in these sorts of debates with on site staff is "well, it was ok at X regional..."

They may well be wrong, and at a minimum should have articulated clearly what the issue and their thinking was. If that didn't happen, then yeah, there is a valid issue that should be discussed and resolved so everyone can make a better call in the future.

I did look up the specs on the charger model listed in the OP. The specs are a little confusing, but from what I can tell it has three charging rates- 12, 8 and 2 amps. Of those, only the lowest setting would be safe and, in previous years, legal. Whats worse is the product brochure makes it sound like this is entirely automatic and not user controllable (though I find that hard to believe). While there is no rule this year stating you can't use higher charge rates, I would agree with any FIRST personal who requested that you not exceed 6 amps. If you couldn't make sure the charger stayed below 6 amps then having you remove it from the pits would be defensible in my mind. Some teams may be comfortable with a higher charge rate, but I really don't believe it's worth it.

I found the product manual at http://www.northerntool.com/download...als/167821.pdf . Let me know if that isn't actually the same model you have.

[ChrisH]

For future reference, when in conflict with an authority such as the Chief Inspector (volunteer shirt and vest) or Head Safety Judge (green polo shirt) over a rules issue, the proper person to talk to is the FTA. He or she probably has more credibility with the official and is a neutral party in the dispute. They also have access to a complete and up to date copy of the rules to assist in sorting things out.They can also involve the GDC if needed, though I have never personally heard of it being necessary.

While the FTA is mostly concerned with keeping the field running and robots talking, this sort of thing is also part of their job.