a noobish question

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Critters
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a noobish question

Post by Critters »

Well, this will make me sound very dumb. For antweights and beetleweights you can use the Scorpin board(or somthing close) for your drive right? BUT what if you have a spinner? can you run 2 ESC with one battery? or 2 batteries?
if 2 won't you over load the reciver?

EpicentrE
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Post by EpicentrE »

There's no reason you can't power 2 (or as many as are needed) ESC's from one battery - as long as the battery has enough capacity to deal with the load. As for overloading the receiver, are you talking about the BEC supply from the ESC to the RX? If so, as long as the voltage is the same from the BECs, it should be ok to feed them both back into the RX, although I'd like someone who is more electronics savvy to confirm that.
Scott Fyfe-Jamieson, Captain of Epic Robotics. Champion of AWS38/41/42.
http://www.epicrobotics.co.uk

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BeligerAnt
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Post by BeligerAnt »

No! Don't connect two BEC outputs to one receiver. We inadvertantly did that and killed both BEC outputs on a pair of Scorpion Minis :oops:

Connect the battery to all the ESCs in parallel.
Connect one BEC output from an ESC to the receiver.
Connect all the signal and 0V wires from all the ESCs to the receiver.

What this means in practice is that (assuming each ESC comes with a standard servo lead) you cut the (usually) red wire on all but one of the ESCs and plug all the ESCs into the receiver. It doesn't matter which channel the power goes into.

Not sure what Critters meant about overloading the receiver, but it is the BEC in the ESC that supplies power to the receiver. The ESCs take their power from the battery pack directly and take virtually no current from the receiver.

BEC: Battery Eliminator Circuit - provides a 5V supply for the receiver derived from the motor battery (typically 7V or more), thus eliminating the need for a separate 4.8V or 6V battery pack for the receiver.
Gary, Team BeligerAnt

Critters
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Post by Critters »

well, im not new to R.C. i got lots of hobby grade, but from what i know, i think that putting 2 BEC with 2 batteries into 1 reciver wont go over so well. maybe you could cap one BEC?

As for wiring the batteries i have no clue. i know how but the batteres i can get are 7.2v 4000 mah Lipos. i think sharing 7.2 v with 3 motors wont work the greatest.....and that is why i want 2 batteries. I can get an ESC with 2 battery inputs and 2 motor outputs. The use those on electric monster trucks.

The reason for this all is becuase of making a U.S antweight. UK are easy becuase you can just use servos for drive.

Thanks so much!

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Post by EpicentrE »

Critters wrote:The reason for this all is becuase of making a U.S antweight. UK are easy becuase you can just use servos for drive.
You can use servos for a US ant just as well as for any other type of small robot, you just need to use bigger servos, that's all. theres plenty of large servos capable of being rotation and speed modified, and indeed, I have seen a lot of US ants using servos for drive. And by the same token, an increasingly large amount of UK ant builders are using gearmotors for drive, so please don't say 'UK ants are easy', because it would be very easy for someone to take offense to that sort of thing.

As for the rest of your post; Even for a US ant, 4000mah is excessively large - I would've thought you would be safer looking in the 300-500mah range for a pusher/flipper, possibly slightly more for a spinner, although I'm not entirely sure being as I've never built one. Andrew Hibberd had a UK ant with 2 Copal gearmotors for drive (which is what the majority of the US ants use) and it ran perfectly well on 250mah lipos.

Also, you seem to generally misunderstand how one battery powers multiple devices in a system that is set up in the way an RC system is - If you have a 7.2v battery, everything in the system will get 7.2v, whether you have 1,3 or 300 bajillion motors, aslong as the system in whole is not pulling more amperage than the batteries can handle. I can think of no reason why in an antweight (whether it be UK or US) class robot you would ever have a need for more than one battery pack.

Also, with LiPos, its not just the mah that you need to consider, it's also the C rating, which denotes the maximum current draw the battery will support. For example, if you have a 200mah batter with a 5c rating, it will be able to handle current draws of 1000mah (1A) maximum at any one point.

The best thing to do is to take a look at the components you are looking to use, find out what their amperage is under normal load at 7.2v (the manufacturers websites will normally have this information), and work from there.

Hope this helps :)
Scott Fyfe-Jamieson, Captain of Epic Robotics. Champion of AWS38/41/42.
http://www.epicrobotics.co.uk

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Simon Windisch
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Post by Simon Windisch »

Critters wrote:I can get an ESC with 2 battery inputs and 2 motor outputs. The use those on electric monster trucks.
I don't really understand what you mean by that, but earlier you said (I think) that you can only get 4000mAh batteries, which if your weight limit is 454g, shouldn't be a problem.

I had a thought that you're thinking about connecting your motors in series (which I suppose would halve the voltage). I've never heard of a motor controller taking two battery inputs. Why would you want to do that?

All the best with your project.

Simon

P.S. Scott, you're getting mellow in your old age :wink:

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Post by EpicentrE »

Simon Windisch wrote:P.S. Scott, you're getting mellow in your old age :wink:
If you mean not raging at a newbie's questions and someone saying UK ants are easy, I guess I have a bit :P Working in a school has made me realise the things that used to annoy me pale in comparison to what some of the kids get up too :). Kids that some of which I plan to introduce antweights to at an after-school RC car club that we're starting up! (Although I imagine the bad ones won't be interested in RC cars in the first place, so we should be safe ;))
Scott Fyfe-Jamieson, Captain of Epic Robotics. Champion of AWS38/41/42.
http://www.epicrobotics.co.uk

Critters
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Post by Critters »

ok sweet thanks EpicentrE!

What i ment was that was the most powerful battery I can get i think that would be a nice battery for a 6 lbmaybe a 12 lb bot.

So basicly will have to take out one BEC and wire the battery in a parallel.



Well what i ment to say is that UK ant weights are usaly more easy then the bigger bots. They are nice and small making them my fav!

leo-rcc
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Post by leo-rcc »

I think that is the first time i heard someone describe UK ant building as easy. :) In Germany almost 80% of all ants are overweight.
Best regards,

Leo van Miert.
Dutchrobotgames
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Critters
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Post by Critters »

LOL i never thought of that....ok then US antweights are easyer

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