Questions/builds thread.

[Ellis]

Re: Questions/builds thread.

Yep, that's what I have planned. Now to find some 18v batteries and a charger for cheap! Thanks again.

[Ellis]

Re: Questions/builds thread.

Will 18v NiCd drill batteries (cheapest option I think) be able to supply power to 4 12v drills and possibly another drill for a lifter weapon? If not, will NiMH?

I have looked at the thought of wiring two 8.4v, or maybe 9.6v NiMH packs in series but I don't know how I'd charge them? The problem it would seem for any kind of battery, is that the battery itself isn't very expensive, it's the charger for the battery that leaves a serious dent in the wallet.

Any ideas for getting 18v batteries (in the region of 2-3Ah), and a charger, for around 20-30 quid? Drills still seem to stand out to me but they're often NiCd and I don't know if they can supply enough amps for what I'd be asking for.

[Ellis]

Re: Questions/builds thread.

Hi.

Looking for a large car fuse (for protecting the whole bot) in the region of 75-100a. Would I be able to use a fuse as a removable link? When removed it completely disconnects power to the robot, and I can protect the thing at the same time. I am referring to something like this... http://www.ebay.co.uk/itm/100-AMP-100A- ... 4150aa2598

Also, anyone know if the name Dust Devil has been used? Sort of a play on Storm II/Tornado since this robot will effectively be a box with a lifter of some sort.

Thanks.

[mattsdragons]

Re: Questions/builds thread.

its not the best idea since your controller would probably blow at 100a and if it blew before your esc, then the bot will also be dead. just buy a bag of deans connectors and make the up that way

[Ellis]

Re: Questions/builds thread.

Yeah it occurred to me that a global ~100a fuse would be useless, since the chances of every motor in the thing stalling and reaching more than the fuse's rating are pretty low. Also suppose only the motors on the left side stall and due to some act of God reach 40a between them, the main fuse wouldn't blow and the ESC would be at risk.

I think I'll get a 40a fuse for each side, then just as you say, make up a removable link from deans.

If I mounted a decent sized heatsink on each Electronize, would that increase their amp rating?

Thanks.

[Ellis]

Re: Questions/builds thread.

Hi all!

So today we spent a little time making up really crude grub screws for the motors, which are now all done. Next we made brackets up for the front motor mounts. Other than that we brainstormed...

You can JUST picture it now! http://yourimg.in/m/9z9vfp5.jpg

If you hadn't gathered from the photo, our plan is for an axe weapon :twisted:. So far we're still at the stage where we're just making a base plate (1cm chopping board, lol!) with the motors and wheels (which I think it's worth mentioning were ordered on the 22nd or so, and have yet to arrive! I'd be lying if I said I'm not a little frustrated. Oh well, so's life...) to make a little run-about testbed. Next stop is battery packs and charger. We plan to make 2x 15 cell (18v) NiCD packs from old drill batteries, and attack an old charger we have. Should be interesting, lol.

As for powering the axe, we're not even sure yet. We know an electric motor > chain and sprockets > should be reliable and proven. But, we've been thinking about elastic and springs... still thinking.

If we were to go for an electric motor system which I think is most likely, we're unsure about motors. I have 2x 200w 24v scooter motors which we WOULD use if they were 18v or less. They're not really good for us because of that. Has anyone ever used a car starter motor for an axe-like weapon? They're readily available, not stupid expensive, 12v, and they move cars. Surely they're ideal?! This brings me on to my next question...

A car starter motor would draw in the order of 100-130a at stall we reckon (about right?) and because of the nature of the weapon, it would more or less always be stalled. That means we need a speed controller that can handle in excess of 100a continuous. Our budget won't do that. How would a 30a Electronize fair with a MOTHER heatsink? Any ideas? If not, I uhm... don't... know!

I think that's about it. Tomorrow we're hoping these :x wheels will arrive. Plus we'll be out buying bolts and whatnot for construction. Tonight we'll order some 50a fuses, some deans and some heatshrink.

Sorry for the long post, we did very little yet somehow all that ^ came out. God help us when stuff actually starts moving.

[harry hills]

Re: Questions/builds thread.

you could use a relay for the axe

[daliad100]

Re: Questions/builds thread.

If you friction drive the axe then you can avoid stalling the motor.

Not the best solution but not breaking speedo's is worth it.

[psycho_fling]

Re: Questions/builds thread.

rick maas does a controller specificlly for an axe weapon you set the amount of time you want the motor on for

[Max]

Re: Questions/builds thread.

You may have problems with a starter motor as they need modifying to make them go in reverse

[Ellis]

Re: Questions/builds thread.

Thanks for the replies. ^

Today and yesterday we made our battery packs. We took the old 12v drill batteries, and made up two 18v 1.2Ah packs (15 cells each). We wrapped them in plastic bottles, heated the plastic with a hairdryer to shrink it and voila! The cells have been sitting for quite a while, so we're having to cycle the batteries quite hard to bring them back to life. I'm confident that they'll improve, since with each charge>discharge they're taking longer to discharge. I have to say I'm happy with them. They're big, but for a first bot, they will certainly suffice. Also, notice our charger... found in the bins down the road.

You can see some pics of the process and the result. All build pics will be uploaded to here.

[jonny]

Re: Questions/builds thread.

hi, you seem to have your photobucket album set on private

[Ellis]

Re: Questions/builds thread.

That's odd. I didn't set anything to make it private.

Anyway, thanks for the heads up. Should be public now.

[jonny]

Re: Questions/builds thread.

much better

[RogueTwoRobots]

Re: Questions/builds thread.

Nice work with the battery packs
Many people consider making your own battery packs to be a daunting challenge (I used to think so too). But it's one of those things where, after you've done it once, it suddenly seems easy and you wonder what you were ever worried about in the first place.