Batteries
 

I currently am in a debate with my coach over how many batteries to take to competition. I feel that we need to change the battery after each match. He thinks we only need to take 2 batteries to competition. So how many batteries do you take? Do you change after every match? Thanks!!!!!!!
Matt

Re: Batteries
 

We are taking 4. Might buy 2 more.

Re: Batteries
 

i would suggest taking as many batteries as u have chargers =D lol u never know what will happen.. such as a battery didnt charge right.. and who knows what if u have 3 matches lined up in a row? are u going to use a half charged battery?

Re: Batteries
 

heh....we have 7 batteries and 5 chargers and we're worried we don't have enough! This game is going to eat up batteries like crazy

Re: Batteries
 

Bring:

• ALL batteries that are competition legal for matches. 2 isn't always enough.
• ANY Backup Batteries you have around.
• ONE or TWO old batteries (non-legal and marked as such) for practice in the pits (to allow comp. batteries to charge)

Change every match. There is nothing worse than having a battery die mid-match because it wasn't charged. Also, they'll charge "faster" if they've already got some voltage. (Same charge rate, less to fill, faster charge timewise.)

Re: Batteries
 

In my experience, it's always a good idea to have a fresh battery for every match. You won't have a tapering in performance match to match as the battery drains. Makes for a more consistent prediction of what the robot will do and how it will react.

If you do change the battery every match, which you should, two batteries won't be enough. 330 usually brings about 5 - 7 batteries (with enough chargers) - that way you can cycle the batteries ensuring you get a freshly charged one for each match.

Re: Batteries
 

We always bring as many batteries as we can (the change to new batteries last year reduced our supply significantly). We have a constant rotation, and a single person monitoring, removing, and replacing the batteries.

His sole responsibility is that the robot gets a fresh battery after every match, checking it with a meter prior to installation. This ensures that we always go out with a properly installed and fully charged battery every match.

If you get into the eliminations, it is VERY important that you have as many batteries as possible in rotation. We've found ourselves borrowing batteries from other teams which did not make eliminations to pick up the slack.

Re: Batteries
 

merybar,
In reality there is no way to really answer this. Some teams eat a battery almost dead in one match while others can easily go two or three matches or longer. If you plan to just sit and watch during the finals, then you won't need too many. However, if you plan to make the finals, (You have planned to that haven't you?) then you will need a few extra for the later matches. Although you could go begging, you might want to have a few of your own just in case. If you are a small bot with omni wheels and tank drive, then you might be able to get by with three or four. If you don't use omni's and you have a lot of functionality and draw lots of current in turns (this is a turning year ya know!) then I would go with some of the recommendations above.

Re: Batteries
 

We've collected enough batteries to theoretically make it through every elimination match at Championships without recycling previously used batteries (9 divisional matches, 6 Einstein matches).

Re: Batteries
 

We'll be taking four legal batteries (the 2007 and 2008 batteries), and we will most likely drag along one or two of the old Exide batteries for the pit. Last year, we made it through Palmetto (quarterfinals included) on two batteries--and that's with a lot of pushing. One of ours from that year seemed to show its age during a recent demo, but I feel confident that we'll be alright with the smaller amount of pushing in this year's game*.

*I never said that pushing wouldn't happen, just that I don't expect it to be as common as we experienced when playing Rack 'N Roll.

Re: Batteries
 

Batteries are like clamps or money, you can never have enough.

We will bring 6 legal batteries for matches and a couple of old ones for the practice area and at least six chargers.

We will also have 4 backup batteries.

Re: Batteries
 

Our minimum is six legal batteries that have been capacity checked
for a 20 amp load, backed up by a true three stage charger with 5
independent 6 amp banks. The batteries that are not in the robot are
always on the charger. We are usually in a position to help out
alliance partners if we get into the finals. I would not consider coming
to an event with less than four batteries and three chargers.

Eugene

Re: Batteries
 

Team 288 Made it through 2 Regionals and Nationals with just 2 batteries with no problems at all. So it can be done.


We upped it too 5 batteries this year with 5 battery chargers. So it will be a big change from last year.


The amount of batteries you have is up to you.
Minimum 2.
Maximum...200?

Make sure to keep them Labeled.

Corey

Re: Batteries
 

Can't have too many batteries.

Figure 5-6 matches on Friday, 2-4 on Saturday morning with 15-60 minutes between matches. You can get by on two batteries.

However...

If you are in the quarterfinals, semifinals, finals, you will have 6-9 or more matches in just a couple of hours with little recharging time between matches.

Re: Batteries
 

In our teams experience the more the better. Espacially when you get into the elimanation (playoff) rounds. You are going through rounds so fast you can really eat up batteries fast. Then again I have seen robots go 3 sometimes 4 rounds and be just fine. Better safe then sorry.

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
894

Re: Batteries
 

1075 is for the first real time taking at least 3 competition legal batteries this year... we seem to have a tendency to blow up a battery or two during a season, they take on quite the round bloated shape :P

188 graciously donated 2 of their brand new batteries to us this year, Thanks 188!

While in their shop though, I noticed quite the stockpile of the older batteries. I would guess probably > 100 batteries, presumably collected over the years many of which labelled as having failed load tests, etc. That would be nice... have enough batteries to have a brand new battery for each match you play all season... bit overkill though

Re: Batteries
 

It's a good idea to change batteries after every match. However, when we use our practice bot we've found that you can go for a few matches before you notice significant problems with low batteries. You can probably survive with two batteries, you just have to be careful.

We've usually got at least 6/7 legal batteries in circulation for matches, with other "illegal" batteries for practicing so that the competition batteries can charge. We also bring at least 6 chargers to match.

Make sure you label your batteries, however many you bring, so you can know how long they've been charging. Also, if one turns out to be faulty, you'll know which one to take out of circulation.

Edit: In the past, we've had to borrow batteries from other teams during elimination rounds. We've also lent out batteries to other teams when they were in need. If you don't have the resources to bring more than two batteries, there are lots of friendly teams out there who will be happy to lend you some batteries so you can compete.