first robot

thanks, they seem pretty cheap and look decent enough.
thinking about getting two of these: http://www.electronize.co.uk/FR12VR_spec.htm
now i just have to search for some good batterys for the motors and buy all the parts and start planning my design.

For batteries, I would also suggest the Vapextech range mentioned above. I have had problems with them in the past in terms of some cells burning out but that was because I was drawing more current from them than was recommended. All the other times I've used them within their limits, they have performed very well.

Using them to power two scooter motors will not push them beyond their capabilities so should be adequate enough for your robot. So for 24V motors you will require two packs of 12V wired in series and, as mentioned, to last a fight or two you really need a 'mAh' (milli-Amp-hours) value of 3000mAh or above. These ones:

http://cgi.ebay.co.uk/12V-3700mAh-NiMH- ... 3353ee4e1a

are 3700mAh and should last at least a couple of fights. Doesn't sound very long but this is the nature of combat robotics. Those packs are also £27 each, which is £54 for 24V. It may seem expensive but you get what you pay for, and these batteries will do a good job.

Best of luck with the design/build and make sure to get some pictures of it up once it's taking shape if you can :)

when you say to wire them in series, do you also mean that both motors will draw power from the same 2 batteries?
cant wait till i get the parts now and start building it :rofl:

That's correct yes. Both battery packs have a negative (black) wire and positive (red) wire. You connect the black wire from one battery to the red wire of the other and then you are left with an unconnected wire from each pack. The voltage from these wires is now 24V. You connect both your speed controllers to your battery wires in parallel (i.e. each speed controller has one red wire and one black wire. You connect the two red wires from your speed controllers to the unconnected red wire from the battery pack and the same for the black wires). This means that both your speed controllers will get 24V and therefore both motors will get 24V.

ok thanks for clearing that up, was getting woried when i thought it may cost me £100 for 4 :)

Haha, no two packs will be enough to get your robot running. You could by another two packs to have as a standby pair so you can swap one pair of packs out when they're flat and put the standby pair in, but that would mean spending £100 as you said :)

However, chargers are pretty good at either slow charging (about 20 hours) or fast charging (~30 mins) so a fully-charged standby pair is more of a luxury than a necessity. With fast-charging, you can go through an event just using two packs without any problem.

thanks for the help so far, but what is the best material to build a featherweight frame out of?
also what would be a good choice of weapon, i want something simple for my first robot but im not too sure if a simple wedge would be able to do much?

It depends largely what sort of power's in the wheels behind the simple wedge, just ramming people can be and has been used as a great tactic and I'm told pinging other robots off the walls at 10-20mph is quite fun :proud:

For your very first robot I would advise concentrating on getting the drive working reliably before thinking about weapons, if when all the construction is done and it works you have weight and space for a weapon I'd add one if you feel comfortable with it. Spinners would probably not be advised for a first build and neither would anything with pneumatics, unless you have a good understanding of valves and forces and the parts required, so an electric axe or lifter would be a good beginners' choice should you find yourself with weight and space to spare :)

ok thanks, il put together my drive system and see how much it ways and what force is behind it before i decide on a weapon.

hdpe is quite good for internal frames

box section and metal skin

or wood :talker: ie block of wood