Cherubim

[blazerbotics]

Correct A123's (LiPofe4?) are allowed, but lithium polymer aren't. Big Nipper are currently testing Lipos in heavies at our events (not sure if RR are letting them at theres), but it'll be a year or so before we come to a decision on them, if they are allowed, their will be very strict rules in place. Most people won't have an issue running A123s, theres a few poeple already one them; Storm 2, Behemoth, Toxic, Thz and a few more.

[PJ-27]

Just to clarify; Lithium-ion or Li-ion are the sort of batteries you find in laptops and phones.

Lithium-Iron-Phosphate (Sometimes called Lithium-Iron, hence the confusion) or LiFePO4 are A123 cells.

To further confused matters Phosphate's chemical symbol is PO, so you have Li and Po in the chemical name of Lithium-Iron-Phosphate which sounds like Li-Po which is Lithium-Polymer, the banned battery in heavies!

Argh!!!!!!! :shock:

[craig_colliass]

Well I'm glad thats sorted

[kane]

Thread Unlocked

[craig_colliass]

Many thanks Kane

After a little break in the work on the Cherub rebuild, things are moving along quite well, I hope to use 24v A123 packs for the power rather than the SLA 24v system used before this has released some weight that has been spent on increasing the base armor from 3.2mm aluminum too 5mm steel armor the same as on the top!

Also the motor for the lifting mechanism is being changed for a 250w drive similar to the motors in Pilgrim and Spiderbot. the ratio is being changed from 300+:1 to about 100:1 this will increase the lift speed by a factor of at least three. also I hope to use some sort of friction drive to reduce the chain damage I have experienced in the past.

The speed controllers will probably stay the same for the moment. but the idea of running the robot at 36volts is something I would like to do in the future.

The inner structure and motor mounting brackets are being completely redesigned to withstand the hammers and crushers that are about at the moment.

The idea is to get it ready for 2013 and give Saint a rest.

[craig_colliass]

Start to the winter build Is going well I had to get another drill for the project as the batteries on the old one were getting past it and the drill was not too far behind. :shock:
At the moment I'm getting the motors repositioned in the robot, done the drive motors now for the lifter motor.

The battery box is made and the link bracket I have decided to completely rewire it as the old routes for the cables have been changed too much, A lot of failures in the arena are due to small errors with the electrics, for me it's usually a link popping out.

Hope to get pics up soon

[psycho_fling]

this has probably been detialed before but struggling to find it, what motor do you use on cherubim's lifter?

cheers alex

[craig_colliass]

This is a good question

The first motor used on the lifter on Cherub was a mobility scooter motor with a gearbox 30+:1 ratio it then had to go through a 2 stage chain drive to get any power to it and as a result it was far too slow.

The motor I am hoping to change it for is similar to the ones in Pilgrim and Spiderbot, these are EMD 24v 12.5A 300w motors gearbox output speed is 140rpm at that voltage I will be running the motors at slightly higher voltages as I'm using A123 batteries in it. this will go through a single stage chain drive 3.75:1 so will spin at around 37-40rpm I am not confident this will be powerful enough and am trying to contact Mike Hamilton-Macy to see if he has any bigger motors to fit these gearboxes.

[psycho_fling]

thanks

[craig_colliass]

Did some tests with the new lifting motor everything went really well till smoke came out. :shock:
Now looking to see if I can squeeze in a Bosch 750w on to the gearbox.
I can't believe I would need this much power just to lift another robot up!
With the Bosch the arms should be good to lift about 250kg That's 1/4 of a tonne that's if the gearbox can take it.