First Ever Robot Build: Invertible Featherweight Vertical Disc Spinner

[Flag Captured]

In what aspect?

(assuming we're saying LiPo chemistry here)
Capacity, I'm sure that plenty of drill-based machines use about 3000mAh for their drives, and 3S should give you that 12v. Or you could go 4s for a bit more speed, if your ESCs will take it.

I used a 5000mAh 4s in my very first machine, which ran drills and that seemed good enough for all intents and purposes. That sort of capacity is overkill though, I will say...

[TheNeonMatt]

Are any brands particularly good/reliable? Also how high could I overvolt a 12V motor before it is likely to cause damage? And finally I get that 3S or 4S is number of cells but what does the mAh mean in terms of performance?
At this point I'm leaning towards 3S as it will be lighter/smaller giving me room/weight for another battery for the weapon. What do people think about going down this route?

[maddox10]

Team RCC uses mainly Zippy and Turnegy for the robots. Not to expensive and easy to replace.

Concerning overvolting. Rule of the tumb is 1.5 times nominal voltage.
Meaning you can feed a 12V motor 18V without blowing it up before it does any real work.
But that same motor can easely burn out with 12V if it is worked hard enough.

mAh is the storage capacity of a battery. A 3S 2000mAh battery contains 11.1V 2Ah= 22.2W of power. The C value is what the battery can deliver in a short time without blowing up.
With LiPo that can go up to 130C, meaning a 2000mAh can deliver the whopping 260A (on 3S 2800W+), but will run empty in about 15-20 seconds.
Most decent LiPo's are 30-40C


Using 3S on a 12V motor is not a bad idea if raw drivepower or speed isn't what you need.

We use a dual battery setup Caliope. A 5S 65C 5000mAh for the weapon, and a 3S 2200mAh 30C for the drive.

[grant_ploughbot]

Just be careful not to get confused between Watts and Watt Hours. Mario's figures above are all in Watts, so that 22.2W of power is actually 22.2Wh. Which means it can give that much energy for an hour. It can supply a lot more power than 22.2W to you system but for a shorter amount of time.

As your unsure of what capacity ratings etc mean, I would recommend using a different battery type for now until you have gained some hands on experience of using and charging batteries before moving directly to Lipos. It's a curve we have all done here as Lipos are a fairly new chemistry, and not as fool proof and safe as other types available. A lot of people now take lipos for granted and recommend them to everyone - however I personally advise caution even to the more experienced roboteer's.

[TheNeonMatt]

I'm currently trying to sort out the drive system of the robot. I need wheels (Banebots probably) and a way to attach them to the drill motor. While having a look around I found this https://www.youtube.com/watch?v=TLGZ-up22tU in which he uses a 3/4" hex hubs with an internal 3/8"UNF thread, does anyone have a better method than this or know where I can find some of the hubs/nuts?

[mrsam]

Ebay for the nuts, just search for 3/4 inch brake pipe connector, this is probably the best method using nut inserts.

[RogueTwoRobots]

I can't remember where I got hex inserts from that I used in that video. It was eBay but I can't remember the user or what I searched for. But I've been very happy with that method for attaching Banebots wheels to drills, been using them on my current FW Reaver, and although the wheels have started to wear and fail, the attachment method is still good and strong.

The downside of this is that Banebots wheels are only available in America so you have to pay for international shipping and customs charges (so best to order in large quantities) and the 125mm wheels that I used in the video are pretty hard to come by any more. Their 98mm size seems to be a bit more reliable.

[maddox10]

3/4" hex is 19mm hex, and that is a normal M12 nut.