can we use 2 batteries?
 

The question was brought up last night if we can use 2 batteries on our robot? is that considered illegal because you would have more power than the other robots or not because either way you're still only going to be running in for only 2 minutes and 15 seconds.

Thanks
Pneumaticsman

Re: can we use 2 batteries?
 

Only one battery may be used at one time. With 2 batteries in serial, you'll be getting twice the voltage (clearly an advantage although it may fry your controls). With them in parallel you get twice the current. Thats an advantage too.

If one of your batteries is for ballast and is not actually acting as a battery, I believe it is allowed.

Re: can we use 2 batteries?
 

No - you cannot use extra batteries for ballast. It doesn't matter what you're doing with the batteries but only 1 is allowed so you'd better use it for power.

Russ

Re: can we use 2 batteries?
 

Ok thank you I just needed some clarification on that. I suppose it's a good thing we can use it as a ballast though cause we're gonna need the weight this year, we're buildin a pretty light bot this year :D

Re: can we use 2 batteries?
 

Dang it now I read Russ Beavis' post that said you can't even use it as a ballast :( sad day

Re: can we use 2 batteries?
 

We have a box of pennies at home that weighs 27 lbs....but, how to secure them? :)

Re: can we use 2 batteries?
 

Last year in the finals at GLR, Mr. Smith from Truck Town lent 1646 a vice grip that we attached to the robot to offset the weight we lost without our arm.

Re: can we use 2 batteries?
 

In a gallon milk jug full of polyester casting resin?

Re: can we use 2 batteries?
 

wouldn't that render the pennies unusable?

ps, if they where shaking around, that would be really loud

Re: can we use 2 batteries?
 

From Section 8 Rev E

<R01>
Energy used by FIRST Robotics Competition ROBOTS, (i.e., stored at the start of a MATCH), shall come only from the following sources:
A.
Electrical energy derived from the onboard 12V battery.

Please remember that anything used for ballast must be securely mounted to the robot frame. The intent as with any object on the robot is to provide the maximum safety for the participants including judges, refs, field reset people and other volunteers near the robot.

Re: can we use 2 batteries?
 

388 has used actual gym weights bolted to the frame, and team 116 has a 27lb (I believe) block of lead.

Re: can we use 2 batteries?
 

Please remember that lead has some nasty properties. If used, it should be sealed in some fashion, paint works well. Teams using lead ballast in the past were required to complete this step to prevent contamination. Please remember to protect team members when working with this substance as it is prepared for a firm mounting on your robot.

Re: can we use 2 batteries?
 

If we need ballast this year (current robot weight is 106) we were considering cutting up some 16 gage sheet steel, and screwing it to the bottom of the robot. It would be several pieces so weight could be adjusted easily if needed.

Re: can we use 2 batteries?
 

Either you have forgotten something major, or you are my hero! :)

Re: can we use 2 batteries?
 

In 2007 we used an eight pound sledge hammer and a bunch of wrenches zip tied to the bottem of our robot to ad weight

Re: can we use 2 batteries?
 

Most of the robot was together and on the scale...honest!

Re: can we use 2 batteries?
 

Last year we used a nice thick steel plate for some added ballast at the front of our robot. Helped prevent tipping, and brought us up to the weight limit. The plate started around 20lbs, but i think we ended up shaving off a little before competing.

hopefully we're under again this year so we can use some more steel plates to offset the battery, which is looking to be on one side of the robot, making us a little lopsided!

Re: can we use 2 batteries?
 

We need a robot before we can worry about ballast... Woohoo crunch time!

Re: can we use 2 batteries?
 

Ballast should be a simple problem to solve. although i like the sledgehammer and wrenches one.

Re: can we use 2 batteries?
 

no point of using 2 batteries anyways just bring a few fully charged battery for back up if necessary the robot would definitely not use up all the power after 1 match. unless if the battery is really old.

Re: can we use 2 batteries?
 

All teams really need to bring multiple batteries and multiple battery chargers to each regional. You should never start a match with anything other than a fully-charged battery and it can often take an hour or two to recharge a battery following a match. Bring plenty of spares!

Russ

Re: can we use 2 batteries?
 

You've obviously never built any high-torque treaded tank drive robots. 1075 has no trouble building a robot whose drivetrain will swiftly kill one of our batteries in as little as 10 seconds.

We had to fix that, obviously, but we were still just barely squeezing 2.5 mins out.

In contrast, our forklift cart powered by 2 12V deepcycle marine batteries in parallel with 2004's IFI system will run for an entire competition weekend on a charge. There is definitely a benefit to be had by running multiple batteries, HOWEVER, its not allowed. C'est la vie.

Re: can we use 2 batteries?
 

This year our robot with trailer hitch and bumpers weighed just over 105 pounds!

Re: can we use 2 batteries?
 

Anyone who has to look at batteries, wrenchs, lead plates, or anything else mentioned deserves an award as far as I'm concerned. Our robot is box, yet we were still only .2 under. You guys are engineering idols.

Re: can we use 2 batteries?
 

in 2007 we added 13 lead diving weights to the robot (zip tied to the frame for lowest possible CG.) The advantage was that they were meant for a diving belt, so they were relatively small, already coated with 1/8" rubber, and had a wide, thin slot for putting zip ties through.