Re: Batteries
 

we take 10 competition batteries, 10 practice batteries, and 2 deep cycle marine batteries, and we use them all!!!!!! especially if we go into eliminations, we supply our alliance with batteries, no joke

Re: Batteries
 

:yikes: :yikes: :yikes: That is 330 lbs of batteries... poor freshmen that have to carry those:D

Re: Batteries
 

:D :D

Re: Batteries
 

Wow, until I saw some of the posts above, I did not think anyone could get through a competition on just 2 batteries. That's amazing and a bit insane.

OK, on Day 1 you have something like 6 matches over 8 hours or so. That's 45 minutes on average between matches - can your charger re-charge a battery in 45 minutes? I say no, which means after the second match, you will go out to the field with a partly charged battery for every match - what a disadvantage!

MK is selling batteries to teams for something like $37 each, buy 2 or 3 more, along with 1 or 2 more chargers (and the Anderson connectors!), assuming you are there to actually compete. If you don;t plan on winning anything, then I guess fewer batteries will be OK.

We expect to bring all 8 of last year's batteries plus six or eight brand new ones, along with 5 or 6 chargers.



Don

Re: Batteries
 

I'd bring everything I could get my hands on XD

Re: Batteries
 

Due to a misreading of the rules, we've done 2 batteries/competition for many years. Yes, it works. No, it isn't a good idea. We'll be bringing four to our regional this year. For the championship, if we find out that we run them down too much, we'll consider purchasing some new batteries or borrowing some from neighboring teams that aren't attending. On a side note, it'd be pretty neat if some of the big regionals (or a championship division) got a sign-up sheet going where teams would sign up to lend fresh batteries to the teams in the semifinal and final rounds. It would make for a more exciting elimination round for all with no real disadvantages.

Re: Batteries
 

We have 10 batteries and 4 backup batteries and i suspect us using them all...

this years robot seems to drain them like crazy!? :ahh: :ahh:

Re: Batteries
 

I do have to say two batteries is sufficient(always better to have more).

We start the regional with 2 fully charged batteries. Use one in the first match. Then put it on the charger (the charger reads that the battery is charged so the battery just needs to be topped off) and put the other freshly charged battery in. By the time we need the first battery it is fully charged or "topped off" once again because it did not loose much charge during the First match.

So once again it definitely can and has been done successfully.

BUT our designs have not had much draw from the battery. Example:Pneumatic parts with an off board compressor.

I do agree a bit insane but I knew no different until I saw teams charging 8-10 batteries last year. It blew me away.


Bottom line. Be prepared. If you get into Finals 2 batteries will not be enough.


Corey

Re: Batteries
 

We take about 15 batteries, with 6 chargers and 6 backup batteries, with 3 chargers. We have a cart that carries all of this. We load it until it can't be loaded anymore with batteries. I would reccomend changing your battery after every match. The only other embarrasing thing other than a dead battery on the field is not turning the bot on itself.:)

Re: Batteries
 

Yes, like most teams who have expressed opinions here, we take as many as we can. On a side note, though, keep your charging and charged batteries organized. Our team has a strip of masking tape on the floor labeled "Charging... Charging... Charged!" and cycles batteries through the line- the longer they sit charging the further up the queue they are moved. Although this will be our first year with our nice new battery charger (five at once!) and not the kit chargers, which tangled the battery cables and rendered such measures extremely convenient/necessary.

Re: Batteries
 

I would absolutely recommend bringing as many batteries as your little tired members can carry! :)

We change batteries every match just in case.

I mean, you wouldn't want your batteries dying in the middle of a match. Especially when the game this year is so fierce and includes a lot of running around.

But you also need to remember that when you are charging your batteries you should be as safe as possible. Charging batteries is extremely important but doing it safely is even more important! FIRST has a website with more information!!

GOOD LUCK! :)

Re: Batteries
 

the more the better we take around 6-8 and use every one we have even created a sub team made of freshmen just to insure that we have a fully charged battery for every match, also in eliminations the "battery boys" performance could make all the difference

Re: Batteries
 

First of all, if you are a rookie team with two batteries and one charger and a regional coming up this weekend... don't panic! Likewise if you are a team that does a lot of travelling by air and knows the pain of paying for an overweight crate, don't feel obliged to pack more lead than you need. You can make it through a competition with two batteries and one charger.... although it is nice if you have access to a third battery and second charger. If you make it deep into the finals and need more juice, you will have probably knocked out at least one veteran team with a swack of batteries who would be happy to share.

Consider that you have four CIM motors running continuously at 20amps each. That is an 80A draw on your battery. Throw in a compressor (or other subsystem) running continuously at 20A. Now let's say the match is three minutes long. That means that in a very high drain match you will draw at most 5 Amp Hours from your battery. Now let's double that amount to account for inefficiencies in the battery and the high charge rate. It would not be unfair to say that the most a team could POSSIBLY draw from one battery in one match would be 10 Amp hours of charge, just over half of the battery's rated capacity. Keep in mind, this is for a three minute match, drawing 100amps continuously... matches are shorter than this, and while peak draw certainly will exceed 100A, average draw will likely be much less.

So for qualifying, you start with two fully charged batteries. After the first match, you swap batteries. The battery you used in your first match will now go on the charger, for on average 1.5 hours, which should bring it back up to almost full charge. (six amps * 1.5 hours = 9 amp hours) The "first match battery" will go in for your third match, while your "second match battery" gets to charge up over lunch and should be good to go for your fourth match, right after lunch. By the time you hit your fifth and sixth matches, your batteries might not be FULLY charged, but will still have enough juice to see you through to the end of the match.

While this is not an ideal scenario, it is a workable one... and is based on pretty much a worst-case level of power consumption on your robot. In our experience we made it through our first year (and last year) with just two competition batteries.... although last year we did bring a third "old" battery for practice time in the pits and a second charger.

Even with just two batteries that should be sufficient to get you through qualifying and the first round of eliminations without much problem. By the time you finish the first round of qualifying there should be plenty of teams with spare batteries that they won't be using who would be happy to help you out on your run to the finals.

When you read posts here of teams bringing ten batteries, you will note that many of those teams are doing this so that they can supply their alliance partners with batteries for an extended run into the elimination rounds.

This year we are bringing four "legal" batteries and three chargers. With intelligent battery management (three batteries always charging) and based on our observed current draw of the robot, that should be sufficient for up to 10 elimination matches... so I'm really hoping that we end up having to borrow batteries from someone!

Jason

(Right... I should be getting ready for Portland... not writing long-winded posts on CD....)

Re: Batteries
 

Don't forget, Spare Parts typically has batteries that are designated for ELIMINATION USE ONLY! So there are about four more batteries per side charging for the previous 2.5 days, just in case someone doesn't have enough juice to make it through the finals. (OK, that's four batteries for 12 teams...6 teams...3 teams, but still...)

Re: Batteries
 

Yea making it to the finals is in our perspective. In my mind we have built the best robot in 7 years this year and im not just saying that. 12 elimination matches possibly. Thats a lot of batteries. THANKS EVERYBODY FOR THE INPUT!!!!!!
Matt Rybar
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