Cicatrix Build Diary

[psycho_fling]

Re: Cicatrix Build Diary

lol you love to have different speedos in one bot different voltages lol

purely a statement no help i know :P

[Anttazz]

Re: Cicatrix Build Diary

I do like making them complicated yes .

Cicatrix worked best when it was at its most complicated though, so sticking with that theory. With any luck it should be a lot simpler this year though.

[RogueTwoRobots]

Re: Cicatrix Build Diary

I can't talk from experience (more just what I remember reading on here) but I think the different discharge rates aren't advised. Although if you balance charge each pack separately I don't think it should make much difference but again, I can't say for sure.

What about just having your 14.8V operating voltage and then using either tx or esc functions to limit the travel (dual rates etc) so that the component running at 7.4V isn't seeing the full voltage?

[typhoon_driver]

Re: Cicatrix Build Diary

You are correct Jamie, it is bad to have cells in series with different tap off points for different voltages. Main reason being is that certain cells will become more discharged than others. The ones with the lower discharge then have to take up the slack so to speak to keep the whole system operating and they will try and charge the higher discharged cells. Not a great situation to be in.

Mind you, a while back as a last minute resort I had to use a combination of A123 cells and nicads (basically what I had left) to get hornet 2 back into the arena. It worked but I was just waiting on the smoke rising out of the battery compartment. What probably helped was that the whole system ran on the same voltage, no tap offs anywhere.

[Anttazz]

Re: Cicatrix Build Diary

Cheers guys I thought as much.

All the cells I am using are the same, two 2s 1500mAh lipos so battery chemistry wont be an issue, its just the discharge rates. Its a Sabertooth 10a I want to limit, so i'll have a look and see what all the dipswitches do on it as I dont think the radiolink gear that robot is using will have anything fancy going for it like duel rates. Suppose I could go low-tech and just physically limit where the sticks can go with a chunk of plastic if it comes to it?

[PJ-27]

Re: Cicatrix Build Diary

Can't you try something like a voltage regulator. Or just running everything no the same voltage. Or limiting the throws on your Tx so that Drive or Weapon only gets half movement, and so in turn half voltage?

[Anttazz]

Re: Cicatrix Build Diary

Cant be bothered with messing around with voltage regulators. I could always just swap over to my DX6 for the moment to this robot and use dual rates. I want the weapon to be run at a higher voltage, if I run the weapon at the same voltage as the drive it will be pretty rubbish and if I run the drive at the same voltage as the weapon there will be a fire

I'm just working on it as I type now, gonna wire it all up as I would do to run it all on the same voltage then try to work out dual rates on my DX6 then maybe have a test video done tomorrow. Or, if I get the rates the wrong way round, i'll have a wanted thread up for new motors

[RogueTwoRobots]

Re: Cicatrix Build Diary

Get a cheap brushless setup from Giant Cod for the drum. Saves the need for faffing around with dual rates and you get MOAR DESTRUCTION!!! :twisted:

[Anttazz]

Re: Cicatrix Build Diary

By cheap what are we talking? I haven't ever even looked at brushless stuff before.

EDIT: Just had a quick look, looks like at that size it could be a lot cheaper than I expected. Definitely something to consider for the future....

I probably have a big pile of money to spend on Cicatrix drum to get it ready for April so i'm gonna be pretty skint very shortly and for a very long time. Well, unless I get a decent job that is, and fitness/tennis instructors with dodgy ankles and knees aren't in very high demand, especially in January with 70mph winds

ANOTHER EDIT: Hang on hang on, how would that help Jamie?

[RogueTwoRobots]

Re: Cicatrix Build Diary

How would what help? Getting a brushless?
If so, then even on 7.4V a brushless will be much more impressive than the brushed motor that's in there at the moment. That way, you can run the whole robot on 7.4V which saves the need to have one voltage going to one ESC and a higher/lower voltage going to another ESC. In turn, that saves you having to worry about setting dual rates or physically limiting the travel of the transmitter sticks.

Although if this is going be doing educational demos, maybe brushless ain't such a good idea

[Anttazz]

Re: Cicatrix Build Diary

Ahhh I see what you mean, I thought you meant just swap the weapon motor for brushless and just run it at 14.8v. would probably be cheaper to buy 2 drive motors that can run on 14.8v. I'm almost certain the ESC would handle that as its pretty much a FW esc, as is the weapons one.

In a way I suppose it would be, to demonstrate brushless over brushed motors, but when it starts going crazy that'd probably be bad :P .

When I get a real job i'll get new drive and weapon motors for it, try to get some gyro dancing on the go

[RogueTwoRobots]

Re: Cicatrix Build Diary

True, I think two of those MFA motors is just over £20 so it probably would work out cheaper. And the higher voltage ones run on 12V+ so they'd do nicely at 14.8V.
And gyro dancing FTW! (is it sad that that's one of the things I'm looking forward to the most with going back to a brushless setup in Drumroll? )

[Anttazz]

Re: Cicatrix Build Diary

Not at all, thats pretty much the big reason i'd want this to be brushless too . Just watch out for the walls this time

[PJ-27]

Re: Cicatrix Build Diary

Dual Rates!? Pah. Just don't move the drive stick as far! Or use Electronize ESC's and turn down the output. Or use a DX5E and the built in mixing with it's stupid half throws, although in your case useful!

[Anttazz]

Re: Cicatrix Build Diary

I was considering just physically limiting the stick, but I dont have any of the things youve mentioned so cant do any of them. Electronize escs would be too big for a BW too I imagine.