Any problems with this idea?

[Steven Sigley]

I've been looking at some ideas for an offseason bot. Does anyone see any thing wrong with using these motors with black jaguars and 2 of the standard FRC batteries connected serially (for 24 volts)
Maybe the batteries wouldn't be ideal, or I'm overlooking some important things?

New Fuse Panel: http://www.wiringproducts.com/conten...use_block.html

Motors: http://www.robotmarketplace.com/products/NPC-02446.html

New breaker: http://www.amazon.com/SGP90200-Sting.../ref=pd_cp_e_0

And 8 gauge wire connecting it all.

The purpose was to make a robot to ride on for 1 or 2 people. I've done it with CIMs but it ends up being slow due to the weight of the chair and person riding.

[linuxboy]

The only thing I can think of is, I remember reading somewhere about certain Jags being capable of 24V and others not being capable of 24V. I'll be honest, I have no idea if that is true, but it may be something to check.

- Oliver

[AlexH]

jags don't really like 24v and high amperage...

since this isn't for first i can recommend these. http://holmeshobbies.com/product.php...4&cat=2&page=1

they are a little more expensive ($100) but will take the amps/voltage. 24v, 80a and have a bec.

also http://killerbotics.com/kbtools/TentacleTools/ has a pretty cool drivetrain calculator that has those motors on it.

[Kevin Sevcik]

The Black Jaguar datasheet doesn't suggest any problems with this setup from the jaguar's standpoint.

If anyone has had a bad experience using black jaguars with a 24V supply and load, I'd be really interested in hearing about that, since the datasheets say that should be fine.

My question is what you're going to be using to control these jaguars. Are you thinking of hacking up something with the FRC PDB connected to just one battery powering the standard FRC control setup?

[Steven Sigley]

Thanks for asking that, I was thinking of just using a vex computer which uses its own separate little battery. So the motors get power from 2 batteries and the computer gets its power from one little one.

[Kevin Sevcik]

Originally Posted by Steven Sigley

Thanks for asking that, I was thinking of just using a vex computer which uses its own separate little battery. So the motors get power from 2 batteries and the computer gets its power from one little one.

That sounds like a sensible approach. Keeping your control system separated from the 24V except for the Jaguar PWM connections should be safe. The servo inputs are optically isolated, so you shouldn't have to worry about your high voltage damaging your lower voltage control side.

[Steven Sigley]

Btw I appreciate that drivetrain calculator. I used it with 2 motors on each side an estimated 220 pound robot. (chair, basic chassis, and person)
Found a battery with similar characteristics to the FRC ones from andymark, and it looks like it will work out. And possibly get some good mph as well.

[theprgramerdude]

The black jaguars shouldn't have a problem, theoretically based on the data sheets, with 24v. Be sure not to stall the motors and you shouldn't have issues, although at the higher voltages, I'm not sure if the diodes for the back-emf can handle the reverse current, depending on the inductance of those motors.

[DonRotolo]

Those motors look a lot like the "big" CIMs from a few years back - other than their being 24 V.

I agree with everyone stating the Jaguars should be just fine with those motors. Some might feel that with twice the voltage the Jaguars might have a thermal problem, but current is the primary dictator of heat in the FETs, not voltage, so there should not be a concern at 24 V.

[remulasce]

Jaguars at 24v will not be your problem. Keeping your two batteries at 24v, however will be. Your batteries will charge to over 12v each, so unless you can find something saying the jaguars are ok with more than 24v, you might accidentally find yourself feeding them too many volts.

I may have read in one of those spec sheets that the jags have a bit of leeway just for this purpose, but just keep in mind your "24v" battery is not actually limited to 24v.