Between-Match Battery Swaps

I cant find anything against it in the rules, but I just want to check for legality:

1.) We CAN change batteries between matches, correct?
2.) We CAN have a total of more than two batteries to swap in/out, as long as only one is ever on the robot, correct?

In the event that both of the above are true, where might we be able to purchase more batteries? If most can get 2 matches out of a single battery with moderate power usage, you should be able to at least one match if you don’t worry about battery consumption, correct?

Yes, you can change batteries out between matches and I would STRONGLY advise that you do this after every match just so your robot doesn’t die.

As for the second part of your question:
5.3.5 Electrical System Rules
<R51> The only legal main source of electrical energy on the robot is the 12VDC non-spillable lead acid battery
provided in the Kit of Parts. That 12V battery is the Exide type EX18-12. The ES18-12 battery, purchased
through your local Exide supplier as a spare, is identical and may also be used. You may use other equivalent
type 12V batteries, but only during the Thursday practice rounds.


  1. Yes, you can change batteries between matches. I highly recommend doing this, it is far too risky to leave your battery in place for more than one match.

  2. You can have as many competition-legal batteries to swap in/out as you desire. This is extremely important to take note of. The batteries take up to 6 hours to charge fully. Our team often brings a minimum of 10 batteries to each competition. At the Boilermaker Regional last year, I believe that we had 12 batteries in the morning and, by the final finals match, we were one of the few teams that still had batteries so we had to supply one battery, not only to ourselves, but also one to one of our alliance partners and one to an apposing alliance member. (we had an uncanny 4 matches in the finals)

As for where to purchase them, try a local NAPA Auto Parts store or Sam’s Club - they are official retailers of Exide batteries, though stock may be spotty. I’d recommend checking online first for a better deal. Exide’s website
also provides a tool for searching for local retailers.

Team Update 4 points to the Official Battery Order Form.

Please read carefully…some suppliers will try and sell you a cross referenced battery that is functionally the same but is not an EX or ES Exide battery. Accept no substitutes.

12 batteries is excessive if you ask me. With the 6A chargers FIRST provides these days, I don’t really see a need for having more than 5 or 6 batteries, even if you have a crazy power-hungry robot. If you kill a battery every match, then you should rethink the mechanical design of your robot. If you plan it right, and you don’t have a lot of back-to-back matches, and your robot doesn’t draw a ton of power, you can certainly get through a regional with only 3 or 4.

However, if you plan to play in the finals, where closely-spaced matches tend to happen, you just might need that dozen or so batteries.

Also, such as at Boilermaker last year, with the 3 on 3 format and smaller regionals you are playing matches closer together. Often times we would come back to the pits and already be called for our next match.

12 batteries is too many unless your robot drains an entire battery per 2 minute game.
Last year, our team could easily get 2 matches from a battery. However, in the final rounds, we used the freshest ones straight off the charger.
The most important advice I can give is to bring more than one charger and always have the batteries charging. Also, be sure to check the voltage of the batteries while their under a load, so that the high voltage from the charger wont confuse you.

we got by last year only using 2 batteries.

The most important piece of advice I can give is have someone assigned to pay attention to the batteries. You cannot imagine how many teams end up saying “I thought you were charging the batteries…”

Our team carries a minimum of 8. They are numbered in a rotation according to their tested charge and pretested load capabilities. The pit setup also runs 4 chargers all the time. We have a pit crew person assigned to keeping track of the batteries and always haviing a freshly charged battery for each round. When we get the round schedule for the day we assign a battery number to each round and that way you never have a dead battery in a competitng robot.

The magic number of 8 serves two purposes. First- by the time you get to the 8th battery, the 1st one is well charged if you need it. Second- in the elimination rounds 8 batteries usually gets you through the three rotations. We have a little rolling cart with numbered slots for our batteries so we can take them to the field for the close-set elim matches.

Like our drivers/players, our batteries must compete for a number in the rotation. They do this by performing well in practice at home and holding the highest charges of the pool (currently 17) Generally they show their gratitude for being chosen by performing well.

Batteries do die after a few years, especially if you crash around a lot. It is always good to have a fresh set for the season…

Also- please dont forget the little auxilliary batteries. Without them you might have some problems with all the sensors this season. They also seem to charge rather slowly.

WC :cool:

Last year 330 made it through 5 rounds of eliminations at nationals with 5 batteries (4 of our own and 1 borrowed).

In 2004, 1405 made it through an entire regional + 3 rounds of eliminations with 2 batteries. We only had to charge each of them once.

Like BrianBSL said, it all depends on how you design.

Our Team 537 last year with only 5 batteries and using the latest for the competitions and the older ones for practice worked out fine.

A tip for charging the batteries is to attach a set of connectors to the end of the charger like the ones that are on the leads for the battery for a good connection.

This can be done by clamping the clips to the end of an extra set of leads and electrical taping it for safety or find the connectors and replace the clips with it.

Good Luck this year!

Assign somebody to the specific task of managing the batteries. If they aren’t on the robot, make sure they are on the charger. Change after every match. You should be okay with about 5 batteries.

For all teams, this is the recommended method of using the charger. Don’t be tempted to use the alligator clips that come with the charger. The clips will damage the surface of the power lock contact, giving you high resistance and a good place to burn during a match. Teams that use the clips this way also run the risk of shorting the output of the charger when you need it the most. Extra pins for the 50 amp connector are available through Terminal Supply or other outlets.

Absolutely. It seems irrational to go through batteries just like that.