Team Death - New Heavyweight

[katch]

Very inventive use of bar bell matey ... THE WHOLE PROJECT LOOKS FUN !!!

[Redirect Left]

Unfortunately this weekend proved to be extremely icy here in Wakefield, and I was unable to safely leave home and walk up to Wakefield Westgate rail station, so had to give it a miss. Have to consider not breaking any bones!

Under load, i'm not sure how those ESCs will perform, or if they do perform as anticipated, how their lifespan will be. The current will only increase under load, up until they (if) they stall, where the current will be at its highest. They only way to find out realistically is to try it though. However for £8 its a bit of a cheaper loss if they do not work, or lifespan is poor.
Assuming those are the ESCs you sent me (here) - they should easily perform at full load (320A is quite a lot). Although two fully charged LiPos will be over voltage. (nearing 30V)
I do doubt that is going to get to 320A though. It's an incredibly small device with a small fan. I'm not sure how realistic the 320 amp max, that is a heck of a lot of heat in need of dissipation.
Do you recall it getting heated during off ground testing?

According to the BBC, the weather will be much milder this week. So i'm hoping that next weekend I can get there and test out these little ESCs. Even if they don't prove viable for movement, they may still be of use to help control the weapons motor, as that'll be very short bursts compared.

Very inventive use of bar bell matey ... THE WHOLE PROJECT LOOKS FUN !!!

I have to say, it certainly has been fun getting to this point. Despite our issues and distance between myself and Colin sometimes causing issue. We've certainly used a lot of varying parts in some inventive ways. How it'll all hold up in battle, will certainly be interesting! Thankfully the majority of its structural components are fairly cheap to re-acquire for replacements!

[Deathly Hallows]

I was watching those on eBay too. Regarding overheating I'd take some tips from overcooking computers. I'd firstly lift the heatsink and put in some thermal compound as at that price be surprised they use any. It may be possible to replace heatsink completely with a better on or perhaps even a liquid cooled solution. Such a bargain item though. If they work I'll be getting some too, at least for my feathers.

[Redirect Left]

Cheers for the advice. We'll keep you updated with our adventures with it, i'm sure.
I probably have some thermal paste lying around from last time I upgraded my PC. They're very small units, so i'm not sure how much area i have to deal with for attaching heatsinks and how effective it'd be with that small area outputting up to 320A worth of heat. If we space things about wisely internally, we might end up with a bit of excess space to play about with some oversized heatsinks. If we can figure out between us all how to make these viable units, they'd be a very cheap alternative, if they can be made to not set themselves on fire faster than Diotoirs fur at high amps, if they do to begin with..

[Maxamuslead]

perhaps even a liquid cooled solution.

considering fans are don't last long in combat robots i would say a liquid solution would fair even worse

[Redirect Left]

Yeah. I don't think liquid cooling is in anyway a workable solution. One good hit would probably dislodge all the plumbing and spill all over every possible electric circuit knowing my luck!

[TechAUmNu]

Is that really 16AWG wire on those ESCs? Since it says they are for 540 motors. I doubt they will manage more than 50A.

[team death]

The Fans on those small speed controllers come on as soon as they are
plugged into the battery-I'm not sure if we will put the two lipos in series
and hope it survives that voltage Adam, not after the Ragebridge blew
which was rated at 35 volt max and these are only 16 volt max-despite
us not knowing the true cause of a spark typical of touching the positive
and negative wires together of a 30 + volt battery.
What was interesting is that there was a no real spark when the lipo
was connected.

[Redirect Left]

It's Sunday! Which means another day of progress, and the most surprising part. Nothing got in the way of me heading up to Colin today!

Today was spent on the electrical side of things. Colin has bought a new ESC, a Cytron MDDS60. This has a max concurrent amp rating of 60 per channel, which is still plenty for us. It also has a wider voltage tolerance, both lower and higher sides.

We firstly started by trying once more to breath life into the Ragebridge, again without success. So we quickly swapped to the Cytron and didn't waste further time with the other for now.
After a short time wiring things up, we had no luck once again, although a quick switch over of the receiever - ESC wires produced results! We've finally managed to get an ESC to fire up, and fully control the motors from the transmitter. We started on the safe side, using some old SLA batteries. The Cytron is significantly larger than the Ragebridge, so if we stick with it, we may need to juggle things around internally, but we'll find a way to fit it in there.

We then decided to move outside, when the weather finally allowed us to do so during a fairly dismal day in Yorkshire. To have a test run outdoors and with an actual floor to see how it performed.
Unfortunately we ran into a few issues here, and the robot was seemingly underpowered. So we switched the SLAs to the LiPos. Even with a single LiPo at around 15V, the robot was showing more life than the 2 SLAs at about 24V were doing. So we placed both of the LiPos in, however this is where the improvement was somewhat limited. It was struggling to move around in a meaningful manner.
We'll spend the coming week and next sunday trying to pinpoint that, if it was a matter of finding traction, not enough current, voltage, if the ESC isn't providing the needed power, or if it is a fault somewhere with the wiring or bot elsewhere. We're confident we can overcome this, and already have a few ideas for things to test and tweak over the coming week.

We also mentioned possibly using the small ESC Colin noted a few posts ago to build a feather or beetleweight with, a potential future project. Whether it'll be a new design, or just a mini version of our current build, who knows!

A few images
1) The ESC almost wired up, and just needs a final connection for a complete circuit. The wooden board here was just used to secure the ESC to, so we didn't accidentally knock it flying.
2) The bot prepped for its first outdoor adventure.

IMG_20180128_142547.jpgIMG_20180128_150057.jpg

[katch]

What lipo did you use was it Charged. ?

I used different receiver inputs off my dx6i to you looking at picture and the speed / response varied for me when I changed them

[team death]

We used 2x4500s (4s) zippy lipos in series, they wern't fully charged I think
Adam said they were around 50%-giving us around 15 volts each so
a total of 30 volts.
What was your optimum set up for the Radio control Katch giving
you the best results?.

[katch]

I used Dx6i with Receiver ar610 I think ..

Left stick Forward back - Speed / ( Receiver throttle)
Right stock Left right mix - Combines motors tank steer ( Receiver Aylerones )

After my first install ( more luck thank judgement) I trialled out the other channels and I didn't get full throttle... but I've never read the manual for dx6i so I could have potential fixed it I just played to see if there was a better combination. Just a suggestion as possible contributor..

I'm testing mine with 12v x 2 and 12v x 3 24v/36v - 200 kilos this weekend. ( bot & 100kg ) so we'll see what happens or breaks.

Only things that affect yours differently to mine that I can see...... may be useful or you can just ignore me

- Chain friction - dry chain is up to 6 - 9% power loss on motorcycles, Using motul wet road lube is by far the best, almost no fling or mess.. so on smaller power sources is a huge power drain. They over heat and snap or get a lot stiffer a they warm up, they also stretch super quick when dry as in 1 inch in a single short ride. Always spray the inside of a chain so centrifugal force push it into the chain where it needs lubing. If I need a chin drive i'll be using 428 O-ring - no stretch no maintenance in comparison. Grease is retained inside the chain so almost never stretch how we use it. Not much heavier.

- Batteries can produce volts with low amps its like a tidal wave - it can read 15v and have 1 amp behind it. You need a lot more than 1 amp ..I've had plenty of arguments with workshop customers, where they claim a battery is NOT at fault as its 6 months old, but we have load tested it and showing 13.5v but fails loads test, barely enough power to light a bulb.
I would try it fully charged

- Your wiring is half the thickness of mine. reduce draw ? not sure .. I have ZERO bullet connectors all big red things

- Your motors are they used ? 24v ? MY used ones are notably slower than my new ones.. worn brushes or bearings

- Gearing combinations, I don't work stuff out I learn and play with trial an error, but...
I see you used a DID motorcycle chain etc - not sure where but... for reference and guiding you.. you can offer it up against your sprockets..

Example Aprilia rs50 - 12 52mm - 47 225mm ratio is 3.92 for a 12bhp motorcycle that weighs around 100 kilos.

So your 24v motors are being expected to work just as hard ( with internal gearbox ) without the benefit of a gearbox, but move the same weight.

Dropping to 10 tooth front -47 Rear is 4.70 - significant acceleration benefits and much faster movement since we operate at sub 10 mph I would go to 8 tooth front if I could.



food for thought.........

[Redirect Left]

We tested it with all the dip switches set to 0. Which is mixed RC input mode, with exponential & MCU modes disabled.
I wonder if it'll get better performance on independent mode instead of mixed.

When I purchased the batteries, I did test that they were able to draw their maximum currents. Which is 202A (45C, 4500mAh, 45 x 4.5). Using a load tester, i achieved satisfactory amounts near to that, however I no longer have the tester to measure an exact output amperage to retest with now.

[RogueTwoRobots]

The main issues I see are the size of wheels, the tyre compound and the gear-ratio. The tyres look very hard and plastic-y, so they probably won't offer much grip. May be worth running a layer of bike tyre around them to improve grip. The wheels are also very close together, which will make turning difficult. The gear ratio from the motor doesn't look that large for the size of wheel so torque may also be an issue.

Obviously changing the gear ratio would be extensive work so maybe try screwing some bike tyre onto the wheels first to see if that improves things. Halfords often have old tyres in the back from bike services that can be obtained for free.

[team death]

You have hit the nail on the head Jamie-very perseptive analysis from
just a set of pictures.
We do have wheel spin and one factor is probably the hard rubber on
the wheels and also the tread.
Another factor is that the Robot is very front heavy and thus the
weight over the back wheels is too light.
The sprocket ratio is around 4 to 1 and altering this is possible
but as you deduce -not an easy task.
The distance between the wheels will have to remain-it would be easier
to cut off the front jaws and have a lightweight heavy than to alter the
wheel spacing.
Conclusion-Fixable