Question?? The PD’s power input
Can I use TETRIX® 12-Volt Rechargeable NiMH Battery Pack to us with The FRC PD’s power input, instead of the regular battery so it is easier to bullied small Robot to teach the new team members?
Sounds like it would work.
No harm in trying, go ahead.
It obviously is not a legal source of power for actual FRC competitions, though. And it’ll run out FAST.
Like, I’m talking a minute or two. MAYBE.
should work OK. but even just the control system will drain the tetrix battery quickly. I think our control system last year drew something like 3.5 amps.
Correct me if I am wrong, but what I am gathering is that you want to build (a) small practice frame(s) to familiarize students with the build and design process. If that’s the case, It may be better to use the full size battery so students will realize how little room they may have to work with for placing electronics and routing wire.
My $0.02
On one hand, 12 volts is 12 volts. Go ahead for practice.
But as Hawiian Cadder mentioned, that tiny Vex battery won’t last long.
We have a desktop system, controls, small motors attached, etc that we use for training.
We power it off of a ham radio 12V supply. Never runs out of power.
Ed
You see I bulid at home for small practice frame with 6 kg battery it is not for my age.
Sorry it dosent work the fuse cutout in a secand
What other parts did you put on the robot? Does it have motors, speed controllers, cRio, ???
We have a small footprint practice bot with cRIO and 4-wheel CIM motor drive interchangeable with regular or mecanum wheels. We use this battery:
It works great. When we add more attachments and motors to the practice bot (e.g. the shooter wheels for this season), we hooked up the regular big lead-acid battery. A picture of our practice bot with the NiMH battery can be found here:
http://www.chiefdelphi.com/forums/attachment.php?attachmentid=11317&d=1326270647
That battery is 10 amp/hours, as opposed to the 17 or 18 amp/hour rating for the FRC leagal battery. Does anyone have any experience using larger batteries with the FRC system? I was thinking that a 40amp/hour marine battery would be excellent for full day demo’s and parades.
What exactly are you powering from it? That battery isn’t good for more than several Amps continuous.
Perhaps a slightly larger 12 volt battery, something around 5-8 Ah? A 5 Ah battery can supply about 10 Amps for several minutes, and 40 Amps for maybe a minute. Remember that a CIM motor can easily draw 40A, so consider what you are putting on the test robot carefully.
Isaak,
A larger battery would/should work fine. One of the sealed, no maintenance batteries is the best choice. However, most of the components in the electrical system are chosen for their ratings based on intermittent duty, i.e. two minute matches. With the derating that was chosen during design, the PD and other components ought to be able to demo most of the day without problems IF cool down periods are religiously scheduled throughout the day. Often teams who take time to change out a battery will give a cool down during the change. Please remember that heat rise in wiring, motors and motor controllers are the most significant problems. These are made worse if the robot is in the sun, in hot weather or both.
The cRIO and the blue plastic pieces (DSC, PD, etc) are all rated for continuous duty: We’ve kept systems running for weeks (months?) with external power supplies without issues.
The cRIO is rated for continuous duty at -20C to +55C: I hope you aren’t making any students march in a parade outside of that range!
After the battery running out of juice, the next most likely failure point is the circuit breakers or motor controllers. If you have an inefficient drive train, they may trip once things have heated up. You may draw significantly more current on the parade surface than on the standard FRC carpet.
If you were using the Textrix battery used for the minibot last year, don’t those have a replaceable (20?) amp fuse built inline?
That might be the problem?